Table of Contents:
- Size and age of the universe
- Are there ways out?
- Did God make the universe look old and large?
So, how big and old is the universe actually? Is it really billions of years old? How can we be so sure?
Occasionally, when I give public lectures I get the question, whether the universe could not be much younger. How can scientists claim to look back in time? Why would you trust those scientists, when the word of God in the Bible claims that the universe with the stars, the sun, and the earth is just 6,000 years old?
Many of my colleagues feel a bit uncomfortable discussing this question in public. However, also these people pay their taxes, some of which finances astronomy research, and so they have the right to an answer. As “public servants” we have the duty to provide them. So, I try.
My answer will be two-fold: physical and metaphysical. Clearly, science has a lot to say on this topic, as the age and size of the universe has been a matter of intense research during the past hundred years. However, also metaphysical – in fact, theological – arguments cannot be left out: are history and nature actually reliable, or are they an illusion? The question sounds strange to many scientists, but it does indeed depend on a particular worldview – a belief – that everyone implicitly assumes.
Let us start with the science. There are countless arguments you may want to make, but which ones are most straightforward? You cannot explain all of astrophysics in a few minutes and the best way forward is usually to start with the big view, before going into details.
To me the most compelling and sufficient argument for a very old universe comes from the sheer size of it and the time it takes for light to reach us: from most parts of the universe it takes millions or even billions of years, rather than a few thousand years. This is what everyone needs to understand and address first.
I will first explain how to measure the size of the universe. The focus will not be on a detailed derivation of the traditional “cosmic distance ladder”, but on simplicity, robustness, and transparency of the argument. The reader is challenged to follow the argument with as little prior knowledge as possible and to dig deeper where desired. After all, we only need a very rough order of magnitude size estimate to distinguish scientifically between the two scenarios. Already with some basic understanding of trigonometry and common sense, it is straightforward to show that the universe is far larger than 6000 lightyears – the distance light can travel in 6000 years.
As a next step, I will address the questions of whether the speed of light could change or whether time could have sped up in the evolution of the universe in order to make a large universe in a much shorter time. The required drastic evolution of the speed of light and time, however, are ruled out by current ultra-precise measurements of light as well as processes we see evolving in front of our eyes in the distant universe.
Finally, I discuss whether the universe could have been created a few thousand years ago, just looking old. This is perhaps a much deeper question and touches on the issue of the reliability of nature and the nature of God. While going against Occam’s razor – and hence considered highly unlikely in the scientific community, strictly speaking such a “created-old” scenario is scientifically not falsifiable. It would, however, imply a creator, whose very nature is unreliable and untrustworthy, setting up a world that gives false witness of its origin. This casts into doubt one of the most basic characteristics of the God portrayed in the very Bible the young-universe idea is derived from in the first place.
Section 2 gives a basic introduction to the measurements of the size of the universe for a general public. Section 3 discusses whether alternatives could make such a large universe young, such as a changing speed of light. Finally, section 4 is a theological discussion on why a model invoking the Bible to explain a young universe is inconsistent with the Bible itself; this section requires some understanding of Christian thinking.
When I lived in the US in the 90’s there was still a general national speed limit on highways of 55 miles per hour. So, everyone was used to drive at a more or less constant speed of 60 mph (since police would let you get away with it): the speed of car was fixed! Hence, my friends would give distances in terms of time. When you asked how far away a city was, people would simply say “about 2 hours”, meaning it was about 120 miles away.
The same is true in astrophysics: we talk about lightyears and mean a distance. A lightyear is 9.56 trillion kilometers – simply the distance light travels in a year. How fast light travels is extremely well established through laboratory experiments and the speed of light is very constant (see Sec. 3.2). In fact, it is so well established, that today we define the meter via the speed of light – simply because we can measure the latter much more precisely than we could make any physical ruler that would define what a meter is![i]
So, while a lightyear is a measure of distance, it is also a measure of age. Light that reaches us from a star a few lightyears away took a few years to reach us and we see how the star looked like a few years ago, when the light was sent on its journey.
Hence, the sky is like a photo album, where you see pictures from different parts of your life. Looking at objects at different distances means you always look at different phases of the universe[ii]! So, yes you can look back in time. In fact, you do it all the time when you look up into the sky.
The basic scale used in astronomy is the Astronomical Unit (AU) – which is the average distance of the earth to the sun: about 150 Million kilometers. Dividing this number by the speed of light, roughly 300,000 km/s, this means that the sun is about 8.3 lightminutes away. We are very sure about this now, since we directly fly spacecraft through the entire solar system.
If you want to find out yourself, you could determine the distance to the sun in principle from the ground with a little bit of travel, a good friend, and by waiting for a Venus Transit. This is how the AU was first determined reliably. The only problem is that we just missed the last Venus transit in June 2012 and the next one is on December 11, 2117. However, there should still be enough data out there on the Internet posted by enthusiastic amateur astronomers to actually redo the calculation yourself.
Figure 1: Venus Transit. The first step is to measure the distance to the sun from different positions on Earth. Calculating the absolute distance then makes use of the fact that the ratio of the velocities of Earth and Venus are given by Kepler’s third law of planetary motion. (Exploratorium.edu)
The AU is crucial, since the next step in our distance determination is fundamentally based on this distance. As the earth moves around the sun, we will be 150 Million km on one side of the sun in spring and 150 Million km on the other side of the sun in fall, meaning that the current location of the earth is always 300 Million km removed from the location it was just half a year ago.
Now imagine you are sitting on a merry-go-round and take a picture of the crowd around you whenever you have made half a turn. The two pictures will not look alike. Your friends and family, standing close to the merry go round will shift from one side to the next on subsequent pictures, while trees and houses at the horizon will only shift a tiny bit, probably not noticeable at all. This is due to a change in perspective. Knowing how large the merry-go-round is and measuring how much people shift on subsequent images you can actually calculate with a little bit of trigonometry how far they are away from you.
Figure 2: The basics of parallax measurements – using small changes of stars on the sky as the Earth revolves around the sun (from ATNF)
The same you can do for stars, using the solar system as a giant merry-go-round (Figure 2). Very nearby stars will shift a tiny bit on the sky between spring and fall, while distant ones will hardly shift at all.
The shift is actually expressed as an angle. To measure the angular distance between two positions on the sky, point a finger at them subsequently and determine by how many degrees you have to move your arm. Of course, the parallax angle itself is so small that you need a much more precise instrument to measure it as discussed below.
The math to turn this angle into distance is pretty much the same as what is used by land surveyors who look through their theodolites and measure the angle between their line of sight towards the top and bottom of a red and white striped rod of a defined length. The further away the rod, the smaller it appears, and the smaller the angle you measure.
It turns out that this is not an easy measurement to do yourself – simply because stars are very far away. The closest star is Proxima Centauri, which is 4.2 lightyears, i.e. 40 trillion km. This star will move on the sky only by 1.5 seconds of arc (or arcseconds in short) between fall and spring!
How much is this? We know what a right angle is. The right angle can be subdivided into 90 degrees. Each degree has 60 arcminutes and each arcminute is divided into 60 arcseconds. Tracking a half circle through the zenith on the sky, will extend over 180 degrees, while the full moon will cover half a degree only.
Figure 3: Coordinates of sources on the sky and their extent are given in degrees of a full circle projected around the earth (burro.case.edu)
As a practical example of small angles, picture a dartboard at the nominal distance of 2.37 m. To hit the bullseye you must have to throw your dart with a deviation of maximally 9 arcminutes relative to the perfect line connecting your hand with the very center of the board. If we would project the annual reflex motion of Proxima Centauri of 1.5 arcseconds onto the dartboard, the projected star would only shift by 17 µm from the center of the board – less than the width of a human hair! You would not be able to notice this shift with your bare eye (let alone hit a bullseye that small).
Such a measurement is very difficult to do and no wonder it took until the 19th century to actually detect a parallax shift reliably. In fact, it still is hard today, but apparently some dedicated amateur astronomers can do it with commercially available telescope equipment – at least in a few cases. So, probably you can do it as well, if you really want to know yourself and are willing to work hard.
Of course, today parallax measurements are much better done from space, where telescopes like the Hubble Space Telescope or ESA’s Gaia mission have measured distances with exquisite precision down to thousands of lightyears[iii]. Here one has to rely on the fact that this diverse group of astronomers and engineers does their job well. In the latest GAIA data release there are 2 million stars for which a reliable distance based on parallax measurements has been determined – a method that still only involves measuring angles.
This is an excellent foundation to stand on for determining distances to even more stars. This is not important for my main argument – we do not need more stars to get the basic scale of the universe, but it may be useful to understand that also the rest of the stars nicely corroborate the story told here.
The reason is that the brightness, temperature, and color[iv] of stars depend mainly on how massive they are. There is a relatively tight correlation between all these parameters, which is reflected in diagrams such as the famous Hertzsprung-Russell diagram (Figure 4), where one sorts stars by color and luminosity and where “normal”[v] stars all fall on one narrow line.
The heavier stars are, the higher the pressure in its center, the higher the central temperature, and the bluer is also the emitted light at the surface. In that sense stars are remarkably simple and can be described by a few basic equations.
Not all parameters can be measured for all stars, but there is enough of a representative sample to cover the entire range of stars we see on the sky. The mass of stars can, e.g., be measured from their rotation speed and orbits, if they are in a binary system, where two stars orbit each other. The surface temperature can be determined from the observed color, based on the formula for black body radiation. This formula is the one that makes melting steel glow more yellow-white the hotter it is.
So, knowing the exact distance for a few stars of a certain type, i.e., a certain color, one can get reliable distances for all other stars of the same type and color, just by measuring how bright they appear in the sky. The further away it is, the fainter it will be.
Figure 4: A Hertzsprung-Russell diagram, which shows that most stars fall on the so-called ”main sequence“ (diagonal line of stars in the center) during the largest part of their active lives. There is a tight relation between the color, surface temperature, intrinsic luminosity, mass and size of a star. Knowing the emitted color we know the intrinsic luminosity of a star and we can estimate the distance to it from its observed brightness on the sky (“spectroscopic parallax ”). White dwarfs and giant stars are stellar phases at the end of the lifetime of a star and can be well distinguished from normal (main-sequence stars) from their emitted light (e.g., their spectra).
However, there is one technique that I am personally more involved with and which delivers even more impressive results: very long baseline radio interferometry, or VLBI. Here radio telescopes distributed over the entire world are combined into one giant network of telescopes that can deliver measurements that are as precise as a telescope the size of the earth. What they essentially do is GPS in reverse. That allows them to do parallax measurements, which are as precise as several tens of microarcseconds[vi].
VLBI does exactly the same as discussed before – measure the relative positions of radio-emitting stars on the sky half a year apart, but now with a much higher precision possible than with any optical telescope today (Figure 5).
Figure 5: Parallax measurements using VLBI
An example of such a measurement is shown in Figure 6. You see that the position of this source on the sky shifts by 0.18 milliarcseconds within half a year and back. This is indeed the reflex motion seen on the sky due to the earth orbiting around the sun. Dividing one Astronomical Unit by half the angle, 0.09 milliarcsecond (=4.4 ×10-10 radians) we get a distance of 36.000 lightyears or 340 quadrillion km (=3.4 1017 km).
Figure 6: Relative shift of the star forming region W49N on the sky (“parallax”) separated by half a year, as measurements with VLBI (from Zhang et al. 2013).
Note, that 36,000 lightyears means that the light was emitted 36,000 years ago. Light had to travel that long to get here in the first place. By now this distant source is much older, but the light from its present state has not reached us yet.
Is this just a freak source or a measurement error? No, the same colleagues of mine at the Harvard-Smithsonian Center for Astrophysics and of the Max-Planck-Institut für Radioastronomie in Bonn have done more of this fundamental work and mapped out the structure of our Milky Way. There are not so many useful radio-emitting stars, but enough to cover one quadrant of our galaxy and to get a reliable sense of the size of our Milky Way (Figure 7). The stars span 14 kiloparsecs, across our own galaxy, which is 45,000 lightyears from one end to the other. These distances are directly measured via their parallax, i.e. the most direct and reliable way to measure distances.
Figure 7: Artist’s impression of our Milky Way overlaid with actual measurements of the location of radio emitting stars (green dots), determined from parallax measurements with radio telescopes. The axes are in kiloparcsec, where 1 kpc is 3260 lightyears. The red dot marks the location of our solar system and the red star is the center of our Milky Way. (Reid et al. 2014)
Of course, we know that the Milky Way has more than one quadrant and hence one can safely assume that the Milky Way extends at the very least 90,000 lightyears.
So, the next time you look up on the night sky in a dark region and you marvel at the Milky Way (Figure 8), remember that it stretches almost 100,000 lightyears from one end to the other!
Figure 8: The Milky Way arching at a high inclination across the night sky (fish-eye mosaic shot at Paranal, Chile). The bright object is Jupiter in the constellation Sagittarius. Galactic north is downwards (ESO).
So far we have discussed only one galaxy, namely our own. What about the others? Well, there is the Andromeda galaxy (also called M31, Figure 9). It is a marvelous masterpiece to look at; in fact, you could see its bright fluffy innermost parts with your naked eye under very good conditions (if you know how to find it). Using binoculars gives a better view.
Figure 9: Picture of the Andromeda galaxy stretching about 3 degrees, i.e., six moon diameters, across the sky (Adam Evans)
What is interesting about Andromeda is that it resembles very much our Milky Way in its properties. Would you sit in the outer parts of this galaxy – as we do in our own, you would see a glowing band very much like our Milky Way at the night sky. This neighbor galaxy is roughly 3 degrees across on the sky. Three degrees correspond to roughly six times the moon (see here, for a photomontage to illustrate this). Hold your thump up against the sky and you can cover the moon or the innermost part of Andromeda.
Now, remember that our own Milky Way extends almost over the entire sky, say 300 degrees, and that the center of the Milky Way is 27,000 lightyears away. You have to extend your arms from left to right to embrace the entire sky and still cover only a little more than half of the Milky Way. How far would you have to move away, so that the entire Milky Way would shrink to the size of the Andromeda galaxy? Well, to get from a 300 to 3 degree size, you need to be a factor 100 further away. Hence, Andromeda should be about 2.7 Million lightyears away.
In fact, our own team had looked at a companion galaxy of Andromeda, M33, and used VLBI to get a geometric distance to it (Brunthaler et al. 2005). The method is very similar to the parallax method, except that we actually saw the galaxy rotate on the sky over the course of years and knew how fast it was rotating from measuring the Doppler effect. The disk of the galaxy is rotating with 106 km/sec, yet the two spots in the disk, we were observing, moved only by 30 microarcsecond per year on the sky.
A car that would drive on the road in front of your house with that speed would move from left to right, i.e. over roughly 180°, in a small fraction of a second (and recklessly endanger everyone living there, of course). The same car moving with that speed on a highway that is a few kilometers away, would seem to take a little longer before it disappears from your view, but probably would be still too fast to track it with your fingers.
How far away do you have to go to catch it appearing as slow as we did? You can calculate[vii] that you have to move stars that rotate around a galaxy with 106 km/second out to 2.4 Million lightyears in order to have them move only such a tiny fraction of the sky within a year. These two simple considerations give basically the same answer: Andromeda and its neighbors must be about 2 and a half Million lightyears away.
A similar technique to get a direct geometric distance has been reported, e.g. by Herrnstein et al. (1999) and Humphreys et al. (2013, and references therein), for the galaxy NGC 4258 (using a disk of water vapor rotating a central black hole). The galaxy is at a distance of 25 Million light years with a 3% error.
Of course, this is still not the end of the universe. There are other methods to go further: step by step. That cosmic distance ladder can be complicated and confusing at times, so we only make a very simple sanity check here.
Have a look at the Hubble Deep Field (Figure 10): this is a deep image of the sky taken by the Hubble Space Telescope. It measures 2.6 arcminutes across, roughly the size of the eye of a needle that you look through while you hold it up against the sky. I usually show this to impress onto people how many galaxies and stars there are in the universe (the image covers only 1/28,000,000 of the total area of the sky, hence there are hundreds of billions of galaxies in the entire universe).
Figure 10: The Hubble Deep Field – a deep image of a random piece of sky showing thousands of remote galaxies. It covers about 2.6 arcminutes of the sky on either side.
However, here we want to get a simple feeling on how far away theses galaxies are. Take a ruler and measure the size of an average (spiral) galaxy in the image. Then measure the total width of the image and divide the two numbers, to express the galaxy width as fraction of the total image size and multiply by 2.6 arcminutes, the size of the image. You will find that these average galaxies are about 0.07 arcminutes or 4 arcseconds wide. Compare this to the angular size of Andromeda of 3×60 arcminutes, which appears a factor 2,500 bigger on the sky.
Now we can play the same game as we did before with Andromeda and the Milky Way. If these galaxies are anywhere near the size of typical galaxies that we know here in our local universe, they have to be a few thousand times further away than Andromeda. This means in order for those galaxies to fit in a tiny speck within the eye of a needle, we are no longer talking about a few million lightyears, but rather tens of billions (1010) of lightyears! The conclusion: the light from these galaxies took some ten billion years to reach us and we see that part of the universe as it was about ten billion years ago.
In fact, there are other independent methods, which give more precise size and age estimates, like the Hubble law, but it all boils down to the same huge numbers for the size and age of the universe!
If you do not like an old universe, what are your options around this? It is intellectually interesting to think about challenges and I will try to discuss them briefly here:
Honestly, I have not heard anyone actually make this claim and it seems to me that it is very hard to deny the truthfulness of the evidence for the large size of the universe. However, in societies of all times truth seems to be whatever conveniently suits ones own political purpose right now and nobody is to be trusted. Already Pontius Pilate revealed this cynic attitude, when Jesus testified in front of him and Pilate simply asked “What is truth?” (John 18, 38). Obviously, he was well aware of how truth can be twisted.
So, maybe all I said above is just fake and a conspiracy? Well, if you have such a deep mistrust of science, there is probably little I could do. After all, I am a scientist myself and part of the same club. However, at the very least I am trying to relate, that these observations are not “just a theory”. They are based on very solid and reproducible empirical evidence. Hence, I have tried to provide some simple steps you can follow yourself in order to make up your own mind.
Parallax measurements to nearby stars you could in principle do on your own. Comparing the size of the Milky Way and Andromeda you can do with your own binocular and your naked eyes[viii]. The raw data used to produce the Hubble Deep Field and to do the astrometric radio measurements mentioned above are all openly available for everyone in the entire world via the Internet through the archives of the Space Telescope Science institute and the National Radio Astronomy Observatory. The original articles are also available for everyone via the Astrophysics Data System. The identification numbers of observations are typically tabulated in the published papers, which allow you to locate the data sets in the archives. The reduction methods are described in the articles and the data reduction software is publically available for free.
When we discuss about open science today, you will find that astronomy has been exercising this to a large extent already for decades.
Yes, you need skills to re-reduce the data yourself and a lot of time, but in principle you could do it yourself. In any case, trained scientists all over the world can re-check it, with relatively little funding. One needs to understand that scientists are not a homogenous block – they are in fierce competition with each other. There is a lot of reward for those who are able to overturn an old dogma and establish a new one. If a young researcher can show that a major result is fundamentally wrong, by not having to invest much more than his or her own time, there is a lot to gain – if he or she can prove the point.
Still, the basic distance scales I have discussed here have stood the test of time over many decades. This is a good sign in itself that with so much data being openly available the basic picture is essentially correct[ix].
This is in fact the question I get the most from the general public. Indeed, my entire argument is based on a constant value for the speed of light: about 300,000 km/s. There is a very solid case for large distances, but the age of the universe only enters via the fact that light from those distant places needs some (finite) time to reach us. So, could not the speed of light change? One could spend an entire book on its own to address this, but I will try to keep it basic.
First of all, be very careful what you wish for. The speed of light is perhaps the most fundamental physical constant we have and essentially all of physics and modern high-tech rests on it. With out it the famous equations of Maxwell, describing radiation, would not work and hot bodies could not cool via radiation, iron would not glow red when heated up, and neither would the sun shine and provide warmth.
Light is something really amazing. It can be described as either electromagnetic waves, i.e., waves where electric and magnetic field lines wiggle through empty space, or as photons, i.e. massless particles which carry a certain energy. This wave-particle duality is itself fascinating, but for simplicity we here picture light only as waves.
You can in principle generate light by moving electric charges up and down. Picture a cowboy with a whip moving his arm up and down. The whip will transport energy from the arm to the end of the whip, where it can create a lot of damage with that energy. However, it takes a while before the energy from the muscles reaches the end of the whip: a wave can be seen traveling along the rope, when the cowboy flaps his arms – the faster the arm moves up and down the more wave cycles can be seen. The number of cycles per second is the frequency of the wave and the separation between wave crests is the wavelength. The separation between two crests purely depends on the frequency with which the cowboy flaps the arms and the speed with which the wave propagates along the whip. The faster it propagates the longer the wavelength. By comparing wavelength and frequency, you can therefore measure the speed of the wave propagation.
It turns out that we can describe all electromagnetic radiation that way. Radio waves are electromagnetic waves with a low frequency (well, this still means Millions or Billions of cycles per second!) and a long wavelength – from hundreds of meters to centimeters, while optical light has a much higher frequency (~500 trillion cycles per second and a wavelength hundred times smaller than human hair (see Figure 11).
Now picture a daring person that catches the end of the Cowboy’s whip: Despite this catch, the cowboy can still move his arm and inject more energy into the whip! The energy from the arm still propagates freely outwards until the other person absorbs it. Hence, the energy is actually stored in the whip for a certain while. Even if the arm had stopped after a very short whiplash, the energy is still propagating until it reaches the end – the longer, of course, the longer the whip is.
Had the cowboy used a stick instead, his opponent could have caught the end of the stick and almost arrested the cowboy’s arm. The coupling between the two would be instantaneous, no waves would exist, no energy would be transferred, nor work be done, just a force exchanged.
Figure 11: „Light“ is one particular form of electromagnetic radiation described by its frequency and wavelength. Radio waves have low frequencies and large wavelengths, while optical light or X-ray radiation have very high frequencies and tiny wavelengths. The product of wavelength and frequency is the same for all these forms of radiation and equals the speed of light. (Lawrence Berkeley Lab)
That is what would happen if you had an infinite speed of light. Light could not carry energy away – in fact, light would not exist. For example, the hot and wiggling electrons in an old-fashioned light bulb could not dump their energy freely into radiation. The same would be true for the hot gas at the surface of the sun. Radiation is a major source of cooling. Without cooling the sun would blow up due to its heat surplus. On the other hand, solar radiation is what heats the Earth surface. Without radiation, there would be hardly any heat and no life as we know it.
This aspect, that light equals energy is deeply engrained in many areas of physics. In fact, one of the fundamentals of thermodynamics states that indeed all intransparent bodies radiate their heat away via light (see black body radiation). The hotter they are the brighter they radiate. Hence, people who get excited and heated up by falling in love literally glow more – albeit mainly in near-infrared radiation.
The theoretical derivation of the frequency spectrum of that heat radiation, the Planck spectrum, actually led to the development of the quantum theory, which we owe our smartphones and computers to.
Of course, you could still have a changing speed of light, could you not? In the beginning of the 20th century scientists thought that light was transported through an invisible “ether” that was supposed to fill the entire universe. Consequently, they measured the speed of light in the direction of the motion of Earth and perpendicular to it. Surely, the speed of light would need to be different it you were to move towards or against the ether? Surprisingly, the famous Michelson-Morley-Experiment showed that the speed of light was always the same, irrespective in which direction the earth was moving. The ether did not exist and light would propagate in vacuum, where there is no reference medium.
How can you then measure speed? After all, if there is only vacuum in the universe, you have no fixpoint to measure any speed and you can only measure your speed relative to another body. For cars that relative body is the road, but you do not know how fast the road itself is moving in an absolute sense relative to “the universe”. The road moves at different speeds relative to the sun, relative to the center of the Milky Way, or relative to the next cluster of galaxies. Similarly, you can only measure the speed of light relative to an observer.
So, does the speed of light an observer measures depend on where the light came from? Then we should measure a slightly different speed of light for every light ray we observe. Also, the speed of light on Jupiter would be different than on Earth and depend in which direction you move. The Michelson-Morley experiment shows this not to be true. The speed of light seems to be constant wherever you measure it and whatever light rays you use to measure it from[x].
Einstein then drew the daring but logical conclusion: If the speed of light is constant, wherever I measure it, maybe something else is changing, namely time and space. What you actually see, when you move faster and faster towards a light beam, is that light waves look compressed or, equivalently, that the light waves seems to be oscillating faster. This simply means that you have a shorter wavelength or a higher frequency, i.e. the light will change color. It also can be understood as changing time and space, depending on how fast two observers travel relative to each other. However irrespective of how fast you go, the light beam will still move with the speed of light relative to you! This became the basis for Einstein’s theory or relativity, which has passed all experimental tests of very different nature – literally with flying colors.
Consequently, implementing a changing speed of light would affect all physical models: thermodynamics, electromagnetism and light propagation, quantum physics and the theory of relativity. The combination of these theories is what our modern technological world is based on. You cannot simply wave your arms and speculate about the speed of light changing, you would fundamentally change all of physics and technology today.
Still, even if we were to succeed to derive a theory that allows major changes of the speed of light, what do the experiments tell us? The speed of light itself is huge, roughly 300,000 km/second, but you can get a rough measurement of this speed by doing a simple experiment at home using a microwave and eggs. Remember, that the speed of light is the same for all forms of electromagnetic radiation, be it radio waves, light rays, or gamma rays.
It is also important to remember that the speed of light relates the frequency of light to the wavelength of light waves[xi] – essentially how fast the wave travels in one oscillation period. Would the speed of light change with time, also frequencies (i.e. colors) and wavelengths of light would keep changing with time.
For example lasers are produced in resonance cavities, where light goes back and forth, with a size tuned to multiples of the desired wavelength. With a changing speed of light you would constantly have to retune your lasers, used in so many devices these days. You would have also have to retune your clocks constantly, as we use frequencies to measure time. In fact, the very Internet you are using to read or obtain this piece would loose synchronization, since it relies on perfectly synchronized light beams in glass fibers. Also, your GPS in your car would lead you astray when changing then speed of light just a little bit, as it compares the arrival times of radio waves emitted from different satellites.
Measuring the speed of light is so accurate these days, that one defines it as a fixed Gold Standard from which one can derive many other units, like the length of a meter (Evenson & Petersen 1976).
So, today formally labs do not even measure the speed of light anymore. They would measure time, wavelength, or frequency. However, given that wavelength, frequency and speed of light are directly related to each other, one can use these experiments to see if anything is changing with time at all.
Special labs can measure frequencies accurately to 16 digits today (Kolachevsky et al. 2009)! Figure 12 shows measurements made in the group of Nobel laureate Theodor Hänsch of the frequency emitted by the simplest atom there is: hydrogen. That frequency is measured using lasers tuned to a certain wavelength and it stays constant to the 14th digit over a couple of years (0.000000000001%). Note that you would need to change the speed of light by 0.25% every year in order to slow it down by factor of 2.3 Million over 6000 years to explain a size of 14 billion lightyears. Would the speed of light change today, it would have been easily seen in such precision experiments.
Figure 12: Laser-based frequency measurements of the 1S–2S Transition in Atomic Hydrogen as a function of time are found to be stable to roughly the 14th digit (Kolachevsky et al. 2009)
So, to invoke a change of the speed of light to save the idea of a young universe, you would have to pose that it was changing almost suddenly in the past, but not at all today within extremely small limits. The problem with that idea is, however, that we can still see back in time looking at a universe in a younger state and measure physical processes there. As I explain in the following, what we find is that also back then the speed of light was not much different from what it is today.
Figure 13 shows images of the remarkable nova outburst of the star V838 Mon. The star is at a distance of 20,000 lightyears and in 2002 suddenly created a bright burst of light. The light travelled radially outwards with the speed of light during that epoch of the universe. It illuminated surrounding dust, which lit up and became visible too. This is what you see in the pictures and it is called a light echo. The images of the Hubble Space Telescope actually show how the light from the central star travels outwards. Having an independent estimate of the distance to this star, we can now measure the growth of the “light bubble” and hence directly determine the speed of light back then[xii]. The conclusion is that for something 20,000 lightyears away, the speed of light cannot have changed much more than 25% – by far not enough to reconcile that source with an age of 6000 years. Similar light echoes were claimed for supernova 1987A in the Large Magellanic Cloud, some 160,000 lightyears away (Sugerman et al. 2005).
Figure 13: Light reflected from dust surrounding the variable star V838 Mon. As time goes by, the light from a bright nova outburst in center reaches larger and larger radii illuminating more and more of the surrounding dust shells. The conclusion is that propagation oft the light has not changed enormously over the past 20,000 years. (Sparks et al. 2008)
However, we can go even further and look for example at the spectra of very distant galaxies billions of lightyears away and do similar kinds of measurements as in the laboratory measurements mentioned above. Scientists do these observations since they actually want to test whether fundamental constants are indeed constant as a function of time. It turns out that even at these distances the frequencies and wavelength emitted by atoms are exactly the same as what we observe today, when taking the expanding universe into account (Uzan 2002, Kolachevsky et al. 2009). These experiments are designed to measure the fine-structure constant, but they also depend crucially on the value of the speed of light (as well as the elementary charge and the Planck constant).
In summary, there is no evidence today that the speed of light is changing or was changing. Even creationists do not seem to invoke this explanation anymore (see here, older claims were just statistical flukes). Of course, physics is never entirely finished, so it is possible that at some point one does find tiny changes in the speed of light and in fact varying speed of light theories do exist outside the standard model of physics. Finding such a variation would be an awesome discovery, worthy of a Nobel Prize, but, given the limits we have today, the effect could never be so large to make the universe significantly younger than it appears today.
Remember to make this theory work, you would have to claim that the speed of light was constant during the past centuries, but at least 2.3 Million times faster in the previous 6000 years! This is like having a snail suddenly run at a speed of 25.000 km/hr – even faster than the fastest unmanned rocket ever fired (see here for a discussion of the speed of snails!). This is not the universe we see out there.
While roaming the Internet I came across another suggestion, raised in a creationist website to explain the “distant starlight problem” (as it is properly acknowledged). Maybe time in the rest of the universe goes much faster, than on Earth and hence what took a week here on Earth took billions of years out there?
The argument involves some form of gravitational redshift, centered on Earth. And indeed, clocks on Earth go 37 microseconds per day slower than in space where GPS satellites orbit the Earth. This time dilation is actually predicted in Einstein’s theory of relativity and accounted for in the GPS navigation system we all use. However, to make gravitational time dilation so extreme that time would go millions of times faster outside of Earth, would require extreme curvatures of space. Only in the very vicinity of black holes or neutron stars – extremely dense concentrations of matter – would one expect such an enormous slow-down of time. However, those object also come with an extreme gravitational attraction that would crush any life on Earth into extremely thin pancakes.
These are theoretical arguments. If in doubt, we could still measure how fast “clocks” ran in the early universe, by looking back in time, i.e. at large distances. That principle of looking back in time still applies even for a young universe.
Interestingly, we actually do see physical processes evolve at large distances in the universe on human time scales, which we can use as rough clocks. For example, explosions like supernovae (Figure 14) or Gamma Ray Bursts happen within seconds, but their explosion shells develop over days, weeks and months and we can see them directly or indirectly expand. There is no evidence that time speeds up or slows down with distance. We do not see that these explosions suddenly run a million times faster, when looking at the early universe.
Figure 14: Radio images of a supernova explosion seen in the starforming galaxy M82 at a distance of 12 Million lightyears. A supernova is a shock wave generated by matter ejected from an exploding star (not a light echo as in Figure 13). The two inlets at the bottom right show how the explosion rapidly expanded within a year. The expansion speed of 12,000 km/sec is not untypical for explosions of this kind. (from here, see Brunthaler et al 2010, Kimani et al. 2016).
There is, however, an effect predicted by Einstein’s theory of relativity that light is stretched and time is slowed down as the universe expands. This makes processes at large distances appear slower than nearby by a factor of a few for sources that are a few billions of light years away. This is normally corrected for in standard cosmology and not discussed much, as it is essentially taken for granted in this kind of research.
However, some astronomers have explicitly looked at the evolution of light coming from these explosions – essentially trying to see if stellar explosions last longer when being further away (Blondin et al. 2008 for supernovae of type Ia or Zhang et al. 2013 for GRBs). While the statistical evidence may be weak (e.g., Littlejohns & Butler 2014) to support seeing the expected time dilation factor (of order of a few) in this data, this clearly rules out any model where time would suddenly speed up by factors of millions!
Hence, the distant and old universe we see evolve in front of our eyes is showing processes evolve at a normal pace. It is not speeding up by any significant factor that could make the universe evolve in a few thousand years.
Maybe the wise approach is to just wait until science comes to a different conclusion? Have not scientific findings changed with time? Science in hundred years will for sure look very different. The science of nutrition advices also changes every year: a while ago more than one egg per day was considered almost deadly (at least in my recollection) and now suddenly they are save to eat. Were not our grandparents smarter than some of these scientists? Why can one not assume that the question of the age of the universe will be answered quite differently in a couple of years?
In fact, I was once asked at a young-vs-old universe conference, what the chance would be for this to happen. I answered that the chance for science to ever show that the universe is only 6000 years old, is strictly zero (and not just a small number). By my personal standards this was, in fact, a rather unusually bold statement, but I did not want to not raise any false hopes. Naturally half the audience laughed at me. How can I say this, if I have actually said in a previous article myself that science is wrong most of the time?
First of all, there is a certain difference between the science of nutrition advices (where I admit to sometimes have my own serious doubts on how credible they are) and that of physics and astrophysics. Stars in the universe do not talk back, they do not change their mind, they do not let themselves be influenced by media, fashion, or researchers and there is no big industry making money with them outside science itself[xiii].
Secondly, science tends to be commonly wrong when research is conducted at the forefront of our knowledge. It is a continuous play of claims and counterclaims, tests, as well as collisions of egos and sometimes hypes. However, in the wake of these discussions a body of research builds up that rarely collapses entirely – at least not in physics!
Yes, it is true, physical knowledge tends to get expanded, modified, but it is not reversed. Newtonian physics from centuries ago, that we all still learn in school, is still perfectly correct under normal conditions and describes most of our daily lives well, despite the fact that Einstein changed our view of space and time fundamentally.
The reason is quite simple: Models in physics are not an opinion that can change, but rather they are a theoretical description of reality. As such, a model may be an approximation and a simplification, but it has to describe reality adequately within the errors. As along as reality is reliable also those models will continue to do their job well for the situations they were created. Sometimes reality becomes more complicated, but then the models need to take extra factors into account and a new model needs to be created.
Hence, if you want to wait for science to change you have to think carefully what you are expecting to change in the arguments given above? Most fundamental to all of this is the size of the solar system. Does anyone seriously believe that this size will change, despite the fact that we are travelling with spacecraft through it? Would it be smart to think Columbus and others[xiv] were wrong and science will eventually discover that the world is flat after all? Would anyone expect that science will change and we discover that the distance between Europe and America shrinks to a size of a few hundred meters only?
Does the latter question sound bizarre? It should sound bizarre, because an even more extreme shrinking of our solar system would be needed in order to make the parallax distances change such that the universe can fit within 6000 light years. What is the chance for this to happen?
The rest of the distance measurement is measuring angles and converting this into distances. The math for this has not changed since the times of Pythagoras and the parallax angles have been measured over and over again by different groups for different sources. These measurements will not change. These distances will not change significantly either[xv].
The same reasoning is valid for the speed of light and the evolution of time. I am very hopeful we will eventually find something interesting that eventually takes us beyond the theory of Einstein. Maybe we will even find some tiny change of the speed of light or an extra effect that makes time go slightly non-linear. However, the magnitude of this effect cannot be that enormous to change the age or the universe from 14 billion to 6000 years. If so, we would have seen it already easily.
This all is not surprising. After all, any new theory will have to still describe reality we live in as Newton and Einstein describe it right now. A better understanding of aerodynamics will never change the fact that airplanes can fly right now. Similarly, a better model of space and time will not change the fact the GPS works right now – a system which we experience to work in our daily lives and which crucially depends on mainstream physics to get distances, the speed of light and time measured here on Earth and in space very precisely.
The hope that science may change and reverse in this particular matter is completely unfounded. If you are stranded on a small island in a big ocean, you should not hope that Earth will shrink eventually and you can swim home, but rather accept the reality and learn to build a solid ship.
The final question I do get once in a while is why God could not have made the universe in an instance as large as it is 6000 years ago? This question sounds utterly crazy to some of my colleagues, but is of grave concern to those who ask it.
In the middle ages this question occasionally arose in the question of whether Adam, as a first human being, could be depicted as having a navel, leading in the 19th century to something like the infamous Omphalos (greek: navel) hypothesis, which claimed that the universe was created young, but purposely made look old to mislead us – in fact, if you extend that idea, the universe could have formed a week ago.
Let me first defend the question briefly, before I try to answer it. In fact, I am not sure this question itself is more exotic than some other hypotheses that are being discussed today in science. After all, there are serous articles in the scientific literature (e.g., Beane et al . 2002), which discuss the possibility whether our universe is not real, but is nothing but a big computer simulation created by a much more advanced alien civilization. These ideas one gets when movies replace traditional creation stories [xvi], but this is still not a reason to not discuss them. Not surprisingly, in a world where virtual realities more and more replace actual realties, the mere concept of reality is being questioned.
Hence, the underlying question is, whether reality and history are an illusion and perhaps misleading. This is indeed quite an important issue and scientifically we simply cannot answer it. If we were created a split second ago with all the memories implemented in our minds and history frozen into this world, then how could we tell yesterday existed?
“Yesterday” is a very abstract concept. It only exists as the memory and the cause of what is right now. The only reason why we believe yesterday existed is, because our experience shows time as a linear progression of things that seem to cause each other. However, what if the “experience” could not be trusted either?
Moreover, human experience suggests that sometimes things “happen out of the blue”. In the past this was attributed to the will of the gods. Today some may argue, this is simply because we do not always have all the information readily available to tell us what actually caused it. The claim is that we could know the future in principle, if we would know all parameters exactly now.
However, that is scientifically not tenable for two reasons. Firstly, one can show that – as a matter of principle – we can never know the entire state of the entire universe, since then also the device measuring these states would need to know its own state accurately and would need to be larger than the universe itself.
Secondly, chance and chaos is part of today’s physics. In processes like radioactive decay of individual nuclei, quantum state transitions of single systems, or even an entire big bang “just happen” – in some theories – “simply because there is a certain statistical probability. For any particular instance, however, it is impossible to identify a concrete cause, why the event happened right now and right here. In these cases, we merely have replaced “the gods” with “chance” and “probability” – the only difference being, that some sense of “purpose” and “reason” was attributed to the former, while none of that is thought to exist for the latter. Claiming any absence of purpose is a worldview and an assumption.
Of course, in a world governed by chance and probability, it may perhaps sound absurd to consider a maturely created universe a reasonable option to consider. After all, what is the chance that a mature and self-consistent universe suddenly springs into existence at some point? The probability is insanely low. However, is it much lower than a universe that evolved to its present state out of a single big bang with the help of a few laws of nature and a set of about 26 natural constants conveniently set to the right values?
This question is related to the famous “fine-tuning” debate that has led many of my colleagues to embrace the idea that a plethora of parallel (and mainly failed) universes exist – the so-called multiverse idea. I am a very bad statistician, but my gut feeling is that it may not be possible to give a scientifically sound answer, whether any one of these scenarios is really more likely than any other. We simply do not know all prior assumptions one has to make about physics, space, and time before, after, and around this universe in order to address this question quantitatively and scientifically accurate (e.g., see article by my Radboud colleague and mathematician K. Landsman who claims that a single universe is statistically not less likely than a multiverse). Hence, believing an immeasurable multiverse is the answer to all questions may be as good or bad science as believing in the creation of a mature universe by an intelligent designer or believing in a single universe that “magically” evolved out of nothing.
Consequently, I think that the question whether the universe was created recently, but only looks mature is in principle a valid question to ask and in fact touches on very fundamental issues. However, answering the question is not possible without taking into account the belief system of those who are asking it.
Scientists simply assume that the universe is “reasonable” and develops according to cause and consequences. This is the basic axiom of science and in my experience this is a very good assumption for the universe as a whole. Admittedly, the existence of cause and consequences is an assumption and it even breaks down when looking at individual quantum systems as discussed above. Similarly, this principle may also break down when pondering the fate of an individual.
Do other assumptions lead to different conclusions? Does religion change this argument? In the following, I will discuss this from a distinctly Christian perspective. After all, Christianity is not only still the largest religion in the world, but it is also the one, which dominated the cultures within which modern science emerged and, of course, the one I personally identify with and trust in.
So, could God not have created the world 6000 years ago and just made it look like it was very old? Personally, I believe he could have, had he wanted to, but does that idea fit the traditional Christian view of the character of God?
In essence, my view is that proclaiming a God who creates a universe that looks old, but that is actually young, would be thinking of God as a magician who tries to fool us. This would make the world and its history appear like a theater play, which is not real, but only show. Even worse, for objects like the exploding star in Figure 14, we would have to say that he had to imprint the explosion into the light that was already under way and the star actually never exploded. After all, 6000 years ago, when the young universe was supposedly created, the light we now see from this explosion was already Millions of light years away from its home galaxy. Yet the light shows an object evolve. That would be truly a Master deception and indeed not be much different from a computer simulation that is suddenly switched on with an already fully evolved universe, that is completely not real.
For any believer this should pose a serious moral problem. Is not truth an overarching theme of biblical revelation? What revelation can you still believe in, if God is so purposely trying to deceive our perception of the real world? What aspect of reality could still be trusted? Such a God would be in stark contrast with the God that humans have experienced in the past, whom they read about in the Bible, and whom they believe to reveal Himself reliably through history.
That history, is not only human history, but is intimately linked to the history of the entire universe. In the biblical book of Genesis, the creation of humans is clearly part of that global history of the emergence of our world. It seems very difficult to claim a reliable revelation of God through human history, but at the same time doubting the revelation of the age-old creation of the universe through the very same history of the world.
For millennia, the knowledge available to humankind was limited. The question of the age of the world was a very abstract and an academic one – initially only debatable among theologians, for lack of any other evidence. In the past one could discuss for ages whether or not Adam had a navel – there was no way to say who was right[xvii]. These times have changed: at least now we can reliably investigate, whether the Earth had a navel or not.
Fundamental to the Jewish-Christian believe is the belief in one almighty God, who is the single creator and origin of everything. A particular important aspect stressed over and over again is that He transcends time, is reliable, truthful, faithful and unchanging. This is nicely expressed in the Psalms, songs of the Old Testament, where it says: “Before the mountains were born or you brought forth the whole world, from everlasting to everlasting you are God.” (Psalm 90:2), or in another passage: “They will perish, but you remain; they will all wear out like a garment. Like clothing you will change them and they will be discarded. But you remain the same, and your years will never end.” (Psalm 102:26-27).
This reliability expressed in the Bible is not only a question of the spiritual reliability of God, but is witnessed and experienced in a reliability of nature itself. As discussed later (Sec. 4.5), this physical reliability is also a prerequisite for humans to be able to function as independent and spiritually accountable beings. Questioning it would be a slippery path for any Christian theology.
On the other hand, the concept of absolute and 100% reliability is rather foreign to humans. We are used to lies, tricks, and alternative truths. Emperors and rules are known to change the truth and their laws to whatever suits their needs. However, the God of the Bible is not!
Even divine mercy is not arbitrary, but comes with consequences. Christianity is forced to look at the dying and resurrected Jesus in order to understand and experience reconciliation with the creator. Simply changing the rules of engagement to suit our shortcomings is not a part of the equation of the God of the Bible. There is a price to be paid for sin and evil – even if God is the one who pays in the end. Cause and consequences are strictly upheld also in this spiritual domain of Christian belief.
When Jesus talks about the unchanging divine laws, stating that “Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled” (Matthew 5:17-20), is that only meant for spiritual laws? Does that not also apply to the entire order this creation is subjected to? What worth are these spiritual laws if God changes the laws of the world within which humans have to operate at will and order does not really exist? If He will not change spiritual laws that humans shall adhere to, why should He fiddle with the natural laws that rocks need to adhere? After all, the laws of nature are the foundation upon which our daily life operates.
Consequently, the first Christian thinkers like the apostle Paul, were convinced that the properties of God are also reflected in His creation. In his letter to the Romans Paul writes “For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse.” (Romans 1:20)
Paul thinks that “God’s qualities … have been seen from what has been made”. The latter refers to things that God made, i.e. His creation. So, we can understand nature with our mind and thereby we will learn something about God. If God’s divine nature includes being reliable, faithful and truthful, His creation shall reflect that as well – and vice versa.
Stating that the universe disguises itself as something that it is not, i.e. is unreliable and deceiving, then also implies that God himself is not to be trusted.
After all, the only obvious purpose of a large universe of billions of light years in size, which was created as such young, would then be to purposely mislead us. Right now we do not “need” the large universe outside our solar system anymore for our existence. God could have created a much smaller universe – just a few thousands lightyears in size to be consistent with a young universe, but He chose otherwise and we find a universe clearly exhibiting old ages.
It is for that reason that I would consider a creation model that involves a universe that bears false witness of its origin is inherently incompatible with basic Christian principles[xviii], which speak of a reliable creator.
Miracles are another issue. I could discuss them at length here. I love miracles, but I will limit myself to the question, why they are not relevant to the discussion of the age of the universe. Miracles are events where suddenly the fate of people changed – usually for the better – in a completely unexpected manner. No explanation is given in the Bible as to how exactly things happened other than it was completely miraculous to those who witnessed it. The stories are written as such eyewitness accounts and not as logbooks of laboratory experiments.
Today we have no way to scientifically investigate how the wine got into the amphorae at the wedding in Cana, when Jesus sent the servants out to fill them with water (John 2:1-10). We do not know what exactly Jesus was walking on, when his disciples saw him on the sea of Galilee late at night (Matthew 14:22–34), and we have no idea how exactly the servant of a Roman centurion was healed (Matthew 8:5-13). The Bible describes sober and concisely what was observed, but does not explain how things happened in detail. A miracle is primarily a life changing experience and it does not even have to be supernatural to be perceived as a miracle. It may, it may not. It is important that the right things happen at the right time. In no way is there a way we can prove – one way or the other – that a particular natural law was violated or not through these stories. Miracles are signs of hope in situations where all hope is lost and not elements of any scientific theory.
In contrast to general perceptions also in the biblical miracles are still the very rare exception rather than the rule. Even Jesus was walking on a plain and simple road most of the time and not on water. Hence, you cannot turn this around and suddenly postulate supernatural miracles at will and make them the rule rather than the exception for the history of our universe. To generate the visible universe in 6000 years, God would have to break, suspend or modify almost every natural law there is in a manner that is completely unpredictable and untraceable. This would not be a “miracle” as an exception, but rather arbitrariness as the default mode of operation. Preaching such a creation “history” does not proclaim the orderly God proclaimed in the Bible.
The point about, the equivalence between the reliability of God and nature can even be made stronger. I would go so far to hypothesize, that the proclamation of a reliable God, which in turn implies a reliable creation, was even a necessary pre-requisite for science to function in the first place and to make it as successful as it is today.
Human rulers can change rules as they like, children like to change rules while they play (and then get into trouble with each other), but God does not and hence nature does not. If the laws of nature would change on such a day-to-day basis, physical laws would become meaningless and no reliable machine could be built. If we cannot trust that the laws of aerodynamics are valid today in the same way they worked yesterday, we would solely have to rely on miracles – or actually luck – for airplanes to fly. I predict, even the most faithful among us would never step into such an airplane unless they had no other choice.
This sounds almost trivial, but the stability of nature is a very fundamental point. We take this stability for granted. However, this may be a cultural selection effect. Probably, the biggest intellectual revolution the Jewish faith had brought about was to replace all the individual gods with a single, almighty creator, i.e., a single unchanging cause and maintainer of this universe,
Had someone grown up in an animistic religion, filled with ghosts and spirits, that have a will of their own, searching for laws of nature would not make much sense. For example, Chinese astronomy was for many centuries way ahead of astronomy in the West, but a comparable picture of a single God as the origin of everything did not exist; neither was there the expectation of natural laws. The universe itself was a complex evolving thing filled with gods and spirits: “Chinese spirits and gods need not be seen as all-powerful, transcendent, or creators of the world. They are intimately involved in the affairs of the world … As the spirits associated with objects like stars, mountains, and streams, they exercise a direct influence on things in this world, making phenomena appear and causing things to extend themselves” (“The Spirits of Chinese Religion,” by Stephen F. Teiser, quoted here).
Similarly, did Babylonian and Greek astrology assemble an impressive body of data on planetary motion and methods to chart and predict them, but this data was again mainly used to predict the will of the gods.
Asking what the laws of nature are would have been rather pointless in such a cultural environment. Unsurprisingly it did not happen there to the extent it would have been necessary to derive the laws of Newton and Kepler.
Hence, I do not believe for a moment that the development of modern science can be seen without the cultural, philosophical and theological background in which it developed. Of course, there are probably multiple factors needed to explain the emergence of science – after all, also the Greeks, Romans, and Arabs laid important foundations, but in the end science broke through in a heavily Christian environment.
The belief in a reliable and accountable reality, which connects past and future via the present, is a fundamental corner stone of science and of the Christian faith – cause and consequences in an orderly creation. Stars do not have a will of their own in Genesis. It is therefore also neither a miracle nor coincidence that science did flourish and develop in the Christian culture. Science and faith are more intertwined than we think. We cannot entirely separate them from each other or completely ignore either of them, when we want to make sense of the world around us.
To use the Bible today to marginalize obvious scientific evidence would therefore mean to ignore thousand years of Christian history and repeat the errors made by a defaulting Church in the late Middle Ages, desperately clinging for its power.
Interestingly, the issue of reliability as well as cause and consequences runs even deeper and has even theological implications. One of the most important biblical stories in this respect is that of Adam of Eve (Genesis 2:4-3:24), which introduces the concept of the “original sin” – the thought that humans have lost their intimate connection to their creator from their very beginning and ever since are doomed to make wrong choices.
Interestingly, orthodox Christians sometimes invoke this Adam as a principal witness against an old universe. The argument essentially is: if Genesis is not historical, then Adam is not historical, then there was no original sin, and there would be no need for salvation[xix]. This kind of thinking may be completely foreign for a non-believer, for whom salvation is an abstract term. However, the need for and the reality of salvation is considered self-evident by those who have experienced it personally. For them, the issue runs very deep and spiritual salvation of humans is as real as physical healing is for those who had once broken a leg or recovered from a virus infection. That healing must have had a physical cause, must it not? Hence, those who were healed and saved may tend towards a version of history that takes their particular experience into account.
As a result, in some communities there is suddenly a connection between a scientific question, namely, the age and nature of the universe and a spiritual truth, namely personal salvation. In this case, scientific results can suddenly cause serious dogmatic and personal pains – and vice versa.
It is thus worth to digging a little deeper into this issue. I would admit that there is indeed an intriguing but subtle link between the spiritual and the natural world worth exploring. However, that link is seriously compromised, when upholding a creation account, which betrays the principle of cause and consequences. The implied worldview would undermine the very principles expressed in the story of Adam & Eve.
After all, a reliable creation and a reliable God, are also the corner stone of human accountability and responsibility. It seems obvious that without rules, there is no wrong doing, without order, no consequences can be foreseen, and without knowledge there is no understanding of good or evil. Order, cause and consequences, and the ability to know and understand the world are crucial for science. They are also crucial for every human to be able to make decisions and take responsibility. Questioning these very principles science is build on, however, also implicitly questions some fundamentals of Christian belief.
The key moment in Genesis 2 is the famous scene where Adam eats the forbidden fruit from the “tree of knowledge of good and evil” (Genesis 2:9). It is interesting in itself that this tree is connected to “knowledge”. The serpent then goes on to say “For God knows that when you eat from it your eyes will be opened, and you will be like God, knowing good and evil.” (Genesis 3:5).
What makes humans special, according to Genesis, is that we can know! As a consequence, we are able to distinguish good from bad and thereby mirror properties of God (of course, with the problem that humans – being human and not godly – are ultimately not able to handle this knowledge properly). However, rarely do we remember that understanding good and evil – and being responsible for it – only works if you have the capacity to foresee and understand the consequences of your actions.
Let me give two extreme examples: Every day somewhere in the universe a star explodes in a supernova, likely destroying an entire planetary system. Even if some form of life were present in this system, nobody would blame the star: it cannot help it and it does not know what it is doing. Unlike humans the star has no knowledge.
Similarly, if we would picture a world without orderly laws of nature you could drop someone from a high tower and not feel guilty: after all, maybe the laws of gravity, pulling the poor fellow to the ground and killing him, might not have existed just a few moments ago[xx]. Even with your ability to acquire knowledge you would be unable to foresee and understand the outcome of your actions.
In a world where cause and consequences are arbitrary, no evil can be committed and in a world without knowledge no evil can be understood. A universe that pretends to have been evolving and to have continually grown in size, but instead was made in discrete unrelated steps, would be such a world where cause and consequence are not to be trusted anymore. Such a universe is like a thief who wants to cover up his deeds and fabricates false clues to mislead the police.
An important aspect of such a reliable world is the notion that the world and circumstances can change, but that the basic rules stay the same. The Christian concept of sin and salvation would be radically different, perhaps impossible, if neither God nor His creation would be reliably the same yesterday and today and forever. (Hebr 13:8). Indeed, the unchanging nature of God is a deep-rooted conviction expressed in the Bible.
Hence, also – or perhaps especially – in a worldview, where the need for salvation is derived from Adam & Eve, an orderly history is needed. The Garden of Eden – the world the first humans were described to live in – already had to have been be a reliable world in order for those humans to make informed choices, based on their newly acquired knowledge. Cause and consequence needed to exist already at this point. They were naturally built into the entire creation[xxi].
On the other hand, if cause and consequence did not play a role in the history of creation, why should the nature of Adam have any consequence at all? After all, the story of Adam is just a play in the theater of creation where the decór is changed unpredictably? How can one claim that events in the past require forgiveness and salvation, if one essentially claims that the past cannot be trusted?
Postulating that rules of nature are misleading, unreliable, arbitrary, or changing, implies that history itself is unreliable. Hence, while a 6000 year old universe is occasionally advocated by some in order to save the historicity of the Bible and to reinforce doctrines like the “original sin”, they actually destroy the very foundation of it. Clearly said: using the historicity described in the Bible, as an argument to question the historicity of nature does not make much sense, because it questions all historicity, including that of the Bible.
Having said that, I do not question the integrity of those who still defend a young Earth creation. Many of them have good intentions and care deeply about their faith.
Some of them simply do not care as much about science, as I do. Some may not have the knowledge or the inclination to understand and read the signs of nature. Some are simply content with knowing that God created the universe – whether this was 6000 years ago or 14 billion years may not make any difference in their daily life. I will disagree with them, I will try to inform then, but I will not impose my view on them – as long as there is no attempt to enforce a young universe model onto the church or onto society. Everyone has the right to his or her own views.
However, when roaming the Internet one can also find a group of “creationist scientists”, who claim to do science and who want to see their science be accepted by everyone. They too start with the assumption that the word “yom” in Genesis 1 implies a 24 hour day and that therefore the earth was created in 144 hours (i.e., 6 days of 24 hours each). Most scholars will likely not agree with that interpretation of yom, since they feel it makes the story of Genesis inherently inconsistent[xxii]. Nonetheless, the 144 hour creation[xxiii] is the central dogma of the creationist belief system and science is mainly a tool for them to reaffirm that view.
Consequently, creationist science requires any “physical reality” to be consistent with that particular interpretation of Genesis. 144hr-creationsim is often led by relatively smart and well-educated men[xxiv] with a solid scientific background. They have their own organizations, their own publications, their own textbooks and their own science conferences. They also have a strong outreach program towards Christian believers with popular science magazines, websites, books and audio-visual media.
Interestingly, Creationism purposely links creationist faith to a new type of science, thereby making their faith subject to scientific tests.
The creationist mantra is that mainstream science is wrong in its big conclusions (after all the large and old universe collides with their own interpretation of the Bible). This is a bold statement, since our entire modern technological world from smartphones and computers to medical apparatuses, airplanes, cars and space crafts are based, explained, and developed on the basis of the scientific progress that was developed throughout the centuries by scientists, many of which who were actually also devout Christians.
Of course, in this day and age it has become very popular to doubt everything that smells like “mainstream”. Are there not scandals and errors abound in mainstream science? Hence, the claim is quickly made that non-mainstream ideas are simply being suppressed.
Indeed, science is a human affair and it includes all human emotions and corruptions. At its forefront science works as a competition. As a consequence scientists need to fight for their own recognition and for money to do their research. However, in the end, whatever is presented needs to work. Ideas, being mainstream of not, are now openly available to every one, they have to be defended in public, they need to be tested by experiments, and these tests need to be reproducible.
In that respect science is not very different from football or any other sports. Before a match, newspapers are full of speculation from players, coaches, experts and fans that know best who should in principle win. At the end of the day one team wins the competition and none of that chitchat plays any role anymore. The final result counts[xxv].
So, if creationists claim their science is better than that of “mainstream science“ they have to demonstrate that and need to win that competition, rather than starting their own competition. The Internet is full of little articles and power point presentations, where creationists try to argue why a certain dating method is flawed or where they present some “creation model” that explains creation in 144 hours. Most of them are on a popular level though, hardly any of them have made an actual impact beyond their own peer group, and even within this peer group these models differ vastly from each other.
Whatever 144 hour creation model is out there, it has to change physics in a drastic way in order to be convincing. So far, this has not happened. There is not a single device or a single technological breakthrough we can attribute to creationist science.
Of course, when looking at these creationists’ powerpoints and lectures as a layperson, one may get confused: are these dating methods perhaps all flawed? Is creationist science the better science, but just ignored?
What I try to teach my students is to look at the big picture first, when they try to develop a new theory. Ask yourself first: can it work at all? Do the order of magnitude numbers make any sense? Only then start worrying about the details!
I have tried the same here: the size and appearance of the universe is there now for everyone to see. In order to explain a universe of a billion lightyears that was created in 6000 years, you have to make enormous, absolutely radical changes to the fundamentals of modern physics. There is no way you can do this with any physics we know and use today. It is not enough to complain about some obscure “dating methods” to prove a young universe, you actually have to shake and revolutionize physics at all fronts in a way no brilliant thinker in the history of mankind has ever done before. None of the science ideas floated so far by creationists comes anywhere near a coherent theory that can stand up against the scrutiny of current experiments and observations. They fail not by a little bit; they fail by a huge margin. Creationist science simply does not hold up to the standard of truth that we require in science. The church should not be content with any lesser standards.
From a Christian perspective studying the nature of creation reveals something about the nature of the Creator. Studying creation is what scientists like me do for a living and they have to do it truthfully and humbly. The universe as presented to us is millions and billions of light years in size, as one can see with very basic measurements. Neither time nor speed of light can be made to change in such a drastic way to make the universe young. Thus, the universe itself tells us that it is not 6000 years old and that it took more than 144 hours to form.
To defend a 144 hr creation one has to question the witness of nature itself and say that the universe only appears old, but in reality it is not. Scientifically, this cannot be challenged, after all the universe could in principle just be a giant deception or a computer simulation, set up with all memories implanted to deceive us. However, such a position is fundamentally incompatible with basic biblical views. As creation reflects its creator, this actually implies a God who is misleading and unreliable. God would have had to build into this universe many intricate features only to mislead and deceive us.
Also miracles are not a way out. In the Bible they are presented as very specific and exception life changing experiences of people rather than the law of the land. Therefore they cannot be invoked as a default mode of operation to explain how the world evolved. Moreover, questioning the historicity of nature altogether also questions the historicity of the Bible – after all Christians believe that God is revealed in the physical world through history. Therefore, the Bible cannot be used as an argument against an old and large universe. To do so today would require one to state that we cannot trust reality at all. Neither would the Bible be trustable in such an anti-realistic worldview.
Nature itself speaks of an almost immeasurable size and of an almost incomprehensible age of the universe. From a Christian perspective this vastness in numbers reflects a creator who is even larger and older than we can imagine. In fact, this feeling of an immeasurable and awe-inspiring size of creation radiates already through the words of biblical writers and prophets. Job (36:26) shouts out “How great is God—beyond our understanding! The number of his years is past finding out.” Jeremia marvels about the incomprehensible number of the heavenly hosts: “… as countless as the stars in the sky and as measureless as the sand on the seashore.” (Jeremiah 33:22).
The prophets of the Bible do not preach a small universe, a small creation, or – for that matter – a small creator. Neither should we.
By insisting on a young Earth in the face of overwhelming evidence, creationists make God not only appear small, they also destroy the very credibility of scripture they seek to uphold. This builds unnecessary, sometimes insurmountable, hurdles to believe and trust the biblical message for those who have not been fed biblical stories from early childhood on.
The warning of church father Augustine still stands after more than 1600 years “Usually, even a non-Christian knows something about the earth, the heavens, and the other elements of this world … Now, it is a disgraceful and dangerous thing for an infidel to hear a Christian, presumably giving the meaning of Holy Scripture, talking nonsense on these topics … , how are they going to believe those books in matters concerning the resurrection of the dead, the hope of eternal life, and the kingdom of heaven, when they think their pages are full of falsehoods on facts which they themselves have learnt from experience and the light of reason?” (from “The literal meaning of Genesis”, AD401, Book 1, chap 19, 39).
Hence, in the light of widely and publically accessible knowledge and experience about the size of the universe, a 6000 year old universe can be firmly and safely rejected on scientific and on theological grounds.
Acknowledgement: I am thankful to a number of colleagues who have critically and constructively commented on various aspects of this paper: Stefan Paas, Gijsbert van den Brink, Cees Dekker, Bram Achterberg, Dan Fabrycky.
[i] This means that in today’s physical units the speed of light is a constant by definition! However, do not get confused. This is mainly done for practical matters and does not mean, we cannot check the constancy of light by experiments. In fact, we can always change the definition for any given experiment, define a standard length scale instead and check if the speed of light changes after all.
[ii] A little twist to this story comes from the fact that we are looking into different parts of the universe in each direction. So, we see a history along different lines of sight with respect to Earth. However, do those different parts of the universe also share a common history, or are they disjoint? It is well established that the universe is isotropic – on average it looks very much the same in all directions from us. However, would that be also true for any other point in the universe? Would other earths in other galaxies see the same history as we do? In that case the universe would also be “homogenous”. It would have only one common history. This is an assumption, but even that can be tested to some degree of precision and the answer seems to be a reassuring yes (e.g., Goodman 1995, PhRvD, 52, 1821, „Geocentrism Reexamined“).
[iii] GAIA data release 1 seems to have a minimum parallax error of 0.2 milliarcsecond. For a measurement with a significance of 5 σ (i.e 1 milliarcsecond), this corresponds to parallax distance of 3000 lightyears.
[v] „Normal“ (or „main-sequence stars“) implies middle-aged stars that are not recently born or have come to the end of their lifetime, where they undergo spectacular changes in structure.
[vi] This is quite something! For a GPS system, which measures our position relative to satellites at 20.000 km height, this would mean measuring relative positions to about 1 mm. This is just barely possible with the most advanced techniques. However, VLBI can do this feat for measuring the relative positions of cosmic sources, since their antennas are much bigger, they use higher frequencies, and they can afford to have big atomic clocks at each radio telescope.
[vii] D=106 km/sec × one year / 30 microarcseconds
[viii] You will be off by a factor of a few, since you will miss the faint outer parts of Andromeda. It will still give you a huge distance.
[ix] This does not take away the fact that individual distance estimates can be off by a factor of a few in extreme cases, but almost never by an order of magnitude.
[x] Note, that the speed of light can be slower, if light is passing through a medium. This is because parts oft he light are absorbed and emitted, interfering with the original ray. This slows the whole light ray down compared to its speed in vacuum.
[xi] The wavelength of a light wave, λ, is given by the speed of light, c, divided by the frequency ν: , λ=c/ν.
[xii] Note, that normally one actually assumes that the speed of light is given and then determines the distance to this object from the light echo. The fact that here both distances agree within the errors, can then be turned around to state that the speed of light did not change by more than ~25%.
[xiii] With astrology being perhaps the exception, but astrology does not fund scientific studies as far as I know. Of course, also the educational structure in some countries could be considered powerful “industries”. Fortunately, there are still hundreds of excellent research institutions that globally compete against each other for funding and reputation in many very different fields. Hence, there is not something like an organized astronomy cartel out there, that could manipulate results on such a scale.
[xiv] Neither Columbus nor his contemporaries believed that the world was flat. That is a common myth, but untrue nevertheless (e.g., M. Rossano 2011). They miscalculated the perimeter of the earth and the location of India, but no informed medieval person thought the world was flat. Actually, Columbus expected to find India approximately where he actually found the Caribbean islands. His sailors were not afraid to fall off the earth, but that India would be much farther away than Columbus thought it was (see also Hannam, “The Genesis of Science”).
[xv] As a side note: in fact, the distance between Europe and America does change! America moves away from us by 17 mm per year due to continental drift and plate tectonics. This is measured – year in, year out – by geodetic VLBI, i.e., with the same radio telescopes and the same technique used to measure the structure of the Milky Way. The result is independently confirmed by GPS measurements, i.e. very different instruments. However, this discovery does not change the basic scale of our earth, rather it confirms plate tectonics and verifies that VLBI is reliable.
[xvi] These ideas were apparently not an April fool’s joke, but were stimulated by the Hollywood movie “Matrix”. The reason that this idea was considered scientifically testable is that a computer simulation would have a certain “granularity” and would also exhibit “glitches”, which one could try to detect. The comparison to ancient creation stories goes even further: also a simulation would have a creator and it solves the fine-tuning argument often invoked by creationists and apologetics.
[xvii] The ancient navel discussion can still be found in some modern Internet blogs (e.g., here, which also provides some historical context and the admission that this discussion was bizarre at times). Interestingly, here modern creationists argue against Adam having a navel, with exactly the same argument I used above. Al Maxey exclaims: „It is my firm conviction that to suggest God created Adam and Eve with navels is to suggest He is the creator of a grand deception, and I simply am unwilling to make such an assertion about my God”. Well, is not the imprinted light of an evolving supernova in a young Universe model an even greater deception? After all, this we can see even now, while Adam’s navel we cannot.
[xviii] I was once asked by a smart and triumphant student how I could be so sure that God would not create a mature universe? After all Jesus did turn water into good wine, which obviously must be old! It may suffice to say that there is no way we can scientifically test this interesting hypothesis. The wine is long gone while the universe – luckily – is still around.
[xix] Of course, in the vast universe of Christian theology the thinking about salvation is much more complex than sketched here.
[xx] Obviously, Jesus recognized this physical law when refusing the temptation to throw himself from the height, not presuming on God and angels to intervene and thus put Him to the test (Matthew 4:5-7).
[xxiii] I use the term “144 hour creation” here to indicate that someone considers the days in Genesis to be of 24 hour length. There are many other Christians thinkers throughout history, who did believe in a „6 day creation“, but considered those „days“ to be of variable length.
[xxiv] It is my personal impression that the gender balance among creationist scientists is even more skewed towards men than in mainstream physics, but I have no solid statistics to back it up apart from some personal encounters and from having quickly scanned over the research staff listed on various relevant websites.
[xxv] I was told that in American college football the ranking of teams is also based on the opinion of journalists and not just results only. If that is true, it might explain why in the US evidence-based thinking sometimes has a hard time … but, I could be very wrong here!