The angular sizes and apparent brightnesses of distant galaxies are consistent with the Doppler model and not with the big bang. To be clear, the universe is indeed expanding because the average distance between galaxies increases with time as these galaxies move through space. But apparently, the fabric of space is not expanding. The FLRW metric is wrong. This affects the estimated sizes of distant galaxies because the FLRW metric predicts a magnification effect that is simply not seen. 

We have previously seen that observations of distant galaxies using the James Webb Space Telescope (JWST) are contrary to the predictions of the big bang but match predictions of biblical creation.  Now, new observations of the angular sizes of distant galaxies challenge one of the essential underlying assumptions of the big bang – that the “fabric” of space is expanding as galaxies recede.  Without an expanding space, a big bang is impossible.  These observations support a new creation-based model of cosmology – the Doppler model – which makes specific quantitative predictions about future observations.

Introduction

In the early twentieth century, Albert Einstein discovered the equations that describe how matter “bends” the fabric of space, which causes the phenomenon we call gravity.  These equations allow us to predict how mass moves through space.  By making certain assumptions and approximations, physicists attempted to apply these equations to the entire universe.  In the 1920s, four physicists independently realized that Einstein’s equations imply that the entire universe could be expanding or contracting, like the surface of a balloon as it grows or shrinks in size.  The mathematical structure of space is called a metric.  And the particular metric that describes an expanding or collapsing universe (under the aforementioned assumptions and approximations) is named after these four physicists: the Friedmann-Lemaitre-Walker-Robertson metric (FLRW metric).

In 1929, astronomer Edwin Hubble published a new discovery he had made which we now call the Hubble law.  Hubble had been measuring the distances to galaxies along with their velocities by measuring the spectral shift of their light.  He found that almost all galaxies are moving away from us; their light had been shifted to longer wavelengths.  The shift of light to longer wavelengths we call redshift.  Amazingly, Hubble found that there was a relationship between a galaxy’s distance from us and its redshift.  The farther a galaxy is, the larger its redshift.  This is the Hubble law.  It basically means that farther galaxies are moving away from us faster than nearby galaxies.  Hubble interpreted the redshifts as being due to the Doppler effect.  The faster a galaxy is moving away from us, the more its light is stretched to longer wavelengths.

One of the physicists who had discovered the FLRW metric, Lemaitre, realized that the Hubble law could be explained if the fabric of space is expanding (just as the FLRW metric allows) rather than being caused by a Doppler shift.  Consider points on a balloon.  As the balloon expands, points that are nearby slowly move away from each other; but points that are already far away from each other move apart much faster.  If galaxies are like points on the surface of a balloon, then an expanding universe would naturally produce a Hubble law.  Most astronomers came to accept the expansion of space as the explanation for the Hubble law and as confirmation that the FLRW metric was correct.

In 1931, Lemaitre speculated that if the universe is expanding like a balloon, then perhaps that balloon started from a size of zero.  This was the first version of what would later be called the big bang.  The big bang assumes that space is expanding according to the FLRW metric and that it started from a size of zero.  Most creation astronomers have accepted the FLRW metric as the correct explanation for the Hubble law but reject the notion that the universe started from a size of zero.  An expanding space does not require or imply that space started with no size at all.  It just means that space was smaller in the past.  How much smaller depends on how old the universe is.

Expanding Space vs Doppler Effect

An expanding space according to the FLRW metric is a fundamentally different explanation for the Hubble law than Edwin Hubble’s original interpretation.  Hubble interpreted the redshifts of galaxies as being due to the Doppler effect as galaxies move through space.  We are all familiar with the Doppler effect in sound waves.  When a car is approaching us, its pitch is higher than when the car is moving away.  Light also does this, although the effect is harder to detect partly because light is so much faster than sound.  But when an object is moving through space away from us, the light waves are stretched to longer wavelengths, and we detect a redshift.

On the other hand, the same effect could be achieved by galaxies that are essentially stationary in a space that expands like a balloon.  Dots painted on a balloon do not move relative to the balloon’s surface.  But these dots will all move away from each other as the balloon expands.  If galaxies are more-or-less stationary in an expanding space, then they will move away from each other.  This also causes a redshift of their light because the light gets stretched to longer wavelengths as it travels through space that is being stretched.  Light from the most distant galaxies has been traveling longer through expanding space and is thus more redshifted than light from nearby galaxies.  So, the expanding space of the FLRW metric naturally results in a Hubble law.

These are two fundamentally different explanations for the Hubble law.  On the one hand, the galaxies could be basically stationary, but the expansion of space carries them away from each other over time.  This is the FLRW metric and can be thought of as dots painted on an expanding balloon.  Alternatively, the Hubble law could be due to the Doppler effect.  Galaxies move away from each other through non-expanding space such that the farthest ones move the fastest.  Let’s call this the Doppler model.  It can be thought of as pocket billiard balls after a break.  The farthest balls move away the fastest, but the table does not expand or contact.

Nearly all astronomers embrace the latter model because it naturally explains why the most distant galaxies should be the most redshifted.  However, the Doppler model could also explain this from a Christian theistic perspective.  Namely, God may have imparted the most velocity to the farthest galaxies for reasons of stability – it prevents the galaxies from all collapsing into a black hole.

Furthermore, big bang advocates must embrace the FLRW metric because the Doppler shift interpretation does not allow for a big bang.  The big bang requires that all space was contained in a singularity billions of years ago.  But in the Doppler model, space does not expand; thus, there never was such a singularity.  If galaxies are simply moving away from each other through space, then you might initially think that they all came from a common central explosion.  But this cannot be the case because galaxies have tangential (“sideways”) motion in addition to their recessional motion.  That is, running time backward, they would “miss” each other and would not converge to a common center.  Thus, big bang advocates must embrace the FLRW metric and cannot consider the Doppler model without abandoning their own origin story.

You might think that it would be impossible to observationally distinguish the Doppler model from the standard model that assumes the FLRW metric.  After all, both models can account for the redshifts of galaxies (although their explanations differ).  Both can make sense of the Hubble law even though the reasons for the Hubble law differ.  Observationally, the two models are nearly indistinguishable.  However, there are two observational effects that differ between the two models.  And recent data from the JWST now allow us to test which model is correct.

Angular Diameters

From everyday experience, we know that a distant object appears smaller in size than a nearby object whose actual size is the same.  The size of an object as it appears to the eye is called the angular size.  The moon, for example, as seen in Earth’s sky, has an angular diameter of ½ degree.  The sun also has an angular diameter of ½ degree, so it appears about as large as the moon in angle.  In reality, the sun is 400 times larger than the moon.  But since it is also 400 times farther away, its angular size is nearly identical to the moon.  This is what makes solar eclipses possible.  The angular diameter of an object is inversely proportional to its distance.  That is, if I double the distance to a given object, it will look ½ the angular size in each dimension.

This applies to galaxies as well.  Consider two galaxies of identical (actual) size.  If one galaxy is twice as far away as the other, it will appear half the angular diameter.  If space is non-expanding, then this effect works at all distances.  Galaxies will continue to look smaller and smaller as we look to increasing distances.

However, in an expanding FLRW universe, things are more complicated.  As light travels long distances in an expanding universe, this will affect the angular diameter we perceive for any distant object.  It will cause its angular diameter to be larger than it would be in a non-expanding space.  The expanding space of the FLRW metric acts a bit like a magnifying glass, causing distant galaxies to appear larger than they would otherwise.  I will not attempt to go through the mathematical details on why this happens.  These are given in the corresponding technical paper.  But it is a well-accepted and mathematically proven principle that expanding space causes distant objects to appear magnified.

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