Demosthenes

Problems with that scheme.

How would matter shrink? I juat don't see any conceivable ways matter can shrink. Everything making up matter, from atoms all the way to the smallest parts would have to be shrinking and how would that be possible? Also, won't as matter shrink, the density will increase until it turns into a blackhole.

Lastly, if matter was to shrink, then the perceived distances between the planets and the sun would be increasing. Think of this way, if the earth and the sun were shrinking, then the distance between the two globes would be increasing as the surface areas of the two bodies are compactified.

[ November 18, 2002: Message edited by: Demosthenes ]</p>

Gauge Boson

A few problems. First, for the shrinking to have that effect on light, the speed of light would have to remain (comparitively) constant. Also, for there to be the required increase in gravitational energy to fit observations, the universal gravitational constant would need to remain completely constant. But this then leaves the Planck length near its original value. With everything shrinking, subatomic particles would quickly collapse to an equivalent size (I say equivalent because nothing on quantum scales has a definite size) smaller than the Planck length. On that scale, however, very exotic and mostly unknown phenomena happen. One thing that is highly probable is that spacetime becomes indeterministic and takes on the form of a 'quantum foam' riddled with sigularities popping into and out of existance. Not good. Of course, Planck's quantum of action could vary to perfectly compensate, but that would really mess things up. Also, this would probably violate conservation of energy. Finally, it would make the light emitted today have a longer proportional wavelength than identical light emitted in the past. So the energy of light from the same phenomena would have been higher in the past. Bad news: this would have meant that Earth would have been sterilized and stripped of an atmosphere by high-energy, high-intensity x- and gamma radiation a few billion years ago, instead of mild visible and ultraviolet radiation. This leaves out the counteless other problems that would arise.
Also, this could not explain observations. For example, it cannot account for the cosmic microwave background radiation.
It might be possible to metaphysically claim that everything is shrinking and the physical constants change to perfectly hide that, but it would still require an expansion. More importantly, that hypothesis is unfalsifiable, mostly because it is meaningless. The only measurements that are possible (indeed, that have meaning) are dimensionless ratios (pure numbers - without units). Whe you say that a building is 20 meters high, you are saying that the ratio of the height of the building to the length of a meter is 20. Since these dimensionless ratios would not change in such a scenario, it is meaningless to say that anything is changing.

Kharakov

How would the universe expand? My original post on the subject I stated that matter was collapsing in on itself- I had to rephrase that statement to clarify it (apparently I didn't do a good job).

The collapse of matter (shrinkage) would have to be occuring at a very slow rate that might not even be detectable due to gravitational attraction at the local level (the andromeda galaxy is getting pulled towards our galaxy due to gravitational attraction while all other galaxies appear to be receding).

If the wavelength of light emitted was larger in the past, and the size of matter is smaller in the present, you have a double whammy on the apparent red shift of light from remote sources.

Answerer

Okay, I don't believe that the above theory will be possible. To accelerate or expand at an ever increasing rate, the universe will require infinite amount of energy just to do that. So if the above theory will to be true, then the vaccum energy, in this case dark energy, will surely be infinite which is an highly impossible pheonmenon unless our universe is infinitely big in the first place.

Gauge Boson

Problem: if the universe is expanding, bound objects, such as planets bound by gravity to the sun, will not be pulled apart appreciably relative to the entire universe. If matter is 'shrinking', OTOH, the apparent expansion would be closer to independent of whether objects are bound or not.

Right... but you would also have the problem of loss of conservation of energy and the fact that light emitted in the past by the same phenomenon would have had a higher energy than today. In all likelyhood, the visible light from the sun a couple billion years ago would have been in the far-UV or x-ray range and the UV would have been in the hard x-ray or soft gamma ray range. They would have had the same intensity, so Earth would have been cooked and its atmosphere blown away.

As for what could cause the universe to expand... this is fairly well understood. General Relativity requires that space is dynamic; that is, it may expand or collapse, but will not remain static. The cause of cosmological acceleration is not yet understood, but its existence seems inconsistent with your hypothesis.

Oh, another problem. Since you require the speed of light to remain (at least comparitively) constant, our visual horizon would expand faster than light. That is, if we can see 14 billion light years away now, we will be able to see more than 15 billion light years away in 1 billion years. This would also cause the Hubble flow to be a non-linear relation. It is, however, perfectly linear (within experimental error).

Gauge Boson

No, it does not require infinite energy. Vacuum energy, an observational fact, is always of uniform density. That is, no matter how much the universe expands, it has the same energy per unit volume. So it is accurate to say that, if dark energy does not turn off, the amount of dark energy in the universe tends toward infinity as time progresses. It balances itself with positive (as opposed to the typically negative) gravitational potential energy, so it always nets zero, like the entire universe appears to. No violation of conservation of energy.

I recommend that you read a very good, easy-to-understand paper on <a href="http://www.arxiv.org/abs/astro-ph/9904049" target="_blank">Why Cosmologists Believe the Universe is Accelerating</a> by physicist Michael S. Turner of University of Chicago / Fermilab Astrophysics Center.

• You might also want to read:
• <a href="http://www.arxiv.org/abs/astro-ph/9805201" target="_blank">Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant</a>
• <a href="http://www.arxiv.org/abs/astro-ph/9807128" target="_blank">Living with Lambda</a>
• <a href="http://www.arxiv.org/abs/astro-ph/9706227" target="_blank">The End of the Age Problem, and the Case for a Cosmological Constant Revisited (old - predates confirming evidence)</a>

Here is an article that offers an alternative to quintessence: <a href="http://www.arxiv.org/abs/astro-ph/0211097" target="_blank">Missing Mass and the Acceleration of the Universe. Is Quintessence the Only Explanation?</a>. It is worth noting, however, that this theory predicts cosmological acceleration for z&lt;1 and cosmological deceleration for z&gt;1 (roughly) and a corresponding discontinuity in the Hubble relation. The only discontinuity that has been found, however, is at about z=6. This is not due to a change in acceleration, however, but rather is an artifact of galactic development. Also, the details of this theory have not been worked out, so it is not known how well it fits all of the data. xCDM (cold dark matter with dark energy cosmology), however, fits the current data perfectly, within current margins of error. Time will tell.

[ November 19, 2002: Message edited by: Gauge Boson ]</p>

Kharakov

I would rather be disproved than maintain an idea with fundamentalist persistence but I must try and explain my theory to you before you dismiss it entirely.

I am not sure that this is an actual problem if you consider the very slow rate of shrinkage that we are talking about. The gravitational attraction between objects can make up for the shrinking (collapse) of matter.

There is only a ~9 minute delay in light travel between the sun and the earth. This is hardly enough for there to be a significant change in the wavelength of light compared to the size of matter. In addition, my hypothesis states that light in the past has a longer wavelength which implies that it has a lower total energy (when compared to energy radiated in the present). This would account for the apparent red shift of galaxies that are very far removed from us in time (millions of light years). The main thing we need to consider is the fact that a red shift in spectrum wavelength of 1 nanometer is the equivalent distance of 27million light years (you need to see that far into the past to get a red shift of 1 nanometer!!!).


I believe my hypothesis works quite well to explain the apparent acceleration of cosmological expansion.

I am not sure what you mean by this? I agree that the speed of light would remain constant. I do not agree that we will be able to see farther than light has traveled. The hubble 'flow' has to be a linear relation in my theory (the greater the time between light propagation and detection, the greater the redshift of the light).

Thanks for your critiques

Gauge Boson

It has nothing to do with what the rate of shrinkage would be. The problem is that bound systems, like planetary systems, galaxies, and clusters, exhibit almost no (apparent) cosmological expansion compared to the regions between clusters. This could not be if the apparent expansion was caused as you have proposed.

You're not understanding the problem. The shrinkage would cause the relative wavelength of light to get longer as time passes. This, unlike cosmological expansion, would also make the same phenomena emit longer-wavelength light now than in the past. So because the sun emits primarily in the visible range now, it would have emitted in the UV range (maybe soft x-ray range) of the spectrum billions of years ago. This would have precluded abiogenesis from occurring then, maybe ever.

It would indeed account crudely for the Hubble relation. However, you are not understanding your own hypothesis. It would cause light to lose wavelength with time, thus creating the appearance of a cosmological redshift (on first examination). But it would have this same effect on the wavelength of light emitted from any given phenomenon. So this poses two problems. First, it would mean that the light from a given phenomenon, when it was emitted in the past, had a shorter wavelength (higher energy) than the same phenomenon emits today. That would result in a violation of conservation of energy and would cause the problems for Earth that I mentioned above. Second, the change in wavelength would be identical for light en route and for the light emitted from a given phenomenon. I did not realize this at first, but it is an equally serious problem. It would negate the apparent redshift.

You cannot back that statement up. M31 is farther away and it shows a blue shift. The scatter in redshift withing our cluster is enormous. This is beacuse clusters are bound objects. Therefore, any relative velocities within a cluster are almost exclusively due to Newtonian dynamics. That is like tossing a handful of pieces of paper into a pond, then saying that they aren't moving apart quickly because the left side of a single piece is not moving appreciably away from the right side. Furthermore, you can't back that statement up because it is demonstratibly false. Redshift is measured in the form of a ratio of the wavelength shift divided by the wavelength of the emitted light. So the same redshift (and hence same relative velocity) corresponds to a different wavelength shift for different emitted wavelengths. Also, 27 million years is not far into the past in cosmological, or even geologic, terms! The universe is more than 500 times older! And there are no 'full' galaxies that close. Perhaps there is a dwarf elliptical or two, but these are so thinly spread that a redshift of one is not good data. Besides, you can't plot a relationship (or extrapolate anything) from one or two data points.

Two problems with that. First, it would not account for the flat or nearly flat topology of the universe. This is a minor problem. My main reason for considering it unable to account for this was wrong, however. As you have read above, there are major problems that, for example, eliminate the Hubble flow. No redshift would be observed so there would be no apparent expansion and no apparent cosmological acceleration. This makes the cosmological constant the hypothesis' least problems.

Now I need to explain the difference between absolute speed and observed speed. When I said (and when you say) that the speed of light remains constant, we are referring to absolute speed. This should be abandoned (I have trouble avoiding this bad habit) because it is meaningless. All measurements are relative. That is, when we say that a football field is 100 yards long, we mean that the ratio of the field length to the length of what we consider one yard is 100. Since the unit size measurements would be shrinking, the observed distance light travels in a year (1 light-year) would increase with time (the same 'absolute' distance would 'fit' more kilometers/miles/etc. into it). Therefore, it would be observed that our cosmic particle horizon would expand faster than light, even though the relative horizon size would not increase in an 'absolute' reference frame (like I said, meaningless). Also, the Hubble flow (the observed redshift-distance relation) in your hypothesis would, at first glance, cause a slightly concave-upward (slope increasing) relation due to the apparent superluminal particle horizon expansion. But now that I think more about it, it is linear. Just not like you think. As I pointed out above, it would be a linear relation with a slope of zero.

Kharakov

True, gravitational attraction does seem to eliminate the effects of matter shrinking.

You're not understanding my proposition.

A) Billions of years ago ALL matter would have been slightly larger than it is now, thus all light emitted would be of a slightly larger wavelength compared to radiation emitted now

B) light emitted from the sun 4.5 billion years ago would not have been in the upper UV strain of light, it would only have red shifted by a 233 nanometers in spectrum (or a 38% difference in wavelength, which translates to a 19% difference in actual size of matter), however, this light interacted with the earth billions of years ago, at a time when the matter of the earth was approximately the same size as the matter of the sun (9 minutes difference in matter size)

I've got to go now, but will finish this later. I just had a new idea to chew on while I do my errands.

Gauge Boson

Because matter was larger in the past, and because the proper ('actual') speed of light is not changing, the proper wavelength would not change, resulting in an overall increase in relative wavelength as time passes. The light en route would undergo the same effects, which is the only way it could cause the apparent redshifts (ignoring the problem with this I mentioned). For the relative wavelength to get shorter with time, matter would have to increase in size. As you look back in time with your scenario, the proper wavelength of light stays the same but matter gets larger. Thus, the wavelength of light would be shorter relative to the size of matter.

As for your example, reverse the effect a show your calculations; then you'll have it right. The sun currently emits at a peak wavelength of roughly lambda=500_nm, per Wein's law, in the yellow-green part of the visible spectrum. Because the meter (if defined in terms of a standard object) was longer in the past (here we are getting on a slippery slope because of the problems with changing dimensional constants that I mentioned before), but the wavelength of light was not, the relative wavelength (the only one that matters) was shorter. This can be thought of as follows: the meter was longer, hence the nanometer was longer. Because the wavelength of light was not longer, fewer nanometers would 'fit' across a wavelength of the light. Thus, the relative wavelength was shorter. So the wavelength of light emitted by the sun, if your figures hold, would have been about lambda=400_nm, on the border of visible and UV wavelengths. However, the realtive diameter of the universe was about 2/3 what it is now in the past. Thus, the wavelength of light would have been about 2/3 as great (actually a little more; the observed realtionship is different for redshifts because it is relative velocity that matters, not density), so it would have been roughly lambda=350_nm. That would have been in the UV range (now that I do the calculations, it would have been near-UV). Of course, this is assuming no change in Wein's law, though the curve would be blueshifted in the past, resulting in a higher relative concentration of high-energy photons than now. What you still seem to be missing is that this effect (The shrinkage of matter) would cause the light the sun emits (not only the light that has already been emitted) to increase in relative wavelength with time. The light that was emitted billions of years ago, when it was emitted and relative to Earth then, had a shorter wavelength. Relative to today, the wavelength is the same, but at the time, the energy of the light would have been higher.

I must add a clarification to one of my prior comments. I remarked that the cosmic particle horizon would appear to receed superluminally. This is true, but I picked bad units as an example. Measuring in light-years, actually being related to the speed of light rather than the size of anything, would result in the appearance of a normally expanding cosmic particle horizon. Here's why: the cosmic particle horizon receeds at the speed of light. The apparent speed of light, however, is increasing with time in this model. So the light-year increases in length at the same rate that the cosmic particle horizon would appear to exceed the speed of light. This perfectly compensates. But if you use units of length based on the size of a standard, the cosmic particle horizon appears to receed faster than light because more units cover the same proper length with time. Of course, our standard unit of length, the meter, is defined in terms of the speed of light. But we would not have done this in the situation you are proposing because it would result in an ever-increasing relative meter size. It would not be enough to notice typically, but it would definitely have effects on atomic clocks.

A strict constraint can be placed on the possibility of this hypothesis. Recently, it has been observed that the fine structure constant was slightly (1 part in 100,000 over 1 billion years) lower in the past (1, 2). The fine structure constant is closely related to the speed of light and this can correspond to a slightly higher speed in the past (3, 4) (we have the same problems with dimensional units (3), but this problem is covered in (4) ). This is opposite what would be expected in your model. So these observations preclude such a model from being an accurate description of the universe.

(1) "Further Evidence for Cosmological Evolution of the Fine Structure Constant". Webb, John K.; Murphy, Michael T.; Flambaum, Victor V.; Dzuba, V.A.; Barrow, J.D.; Churchill, C.W.; Prochaska, J.X.; and Wolfe, A.M. <a href="http://www.arxiv.org/abs/astro-ph/0012539" target="_blank">Available on the arXiv e-print archive</a>.
(2) "Does the Fine Structure Constant Vary? A Third Quasar Absorption Sample Consistent with Varying alpha." Webb, John K.; Murphy, Michael T.; Flambaum, Victor V.; Curran, Stephen J. <a href="http://www.arxiv.org/abs/astro-ph/0210531" target="_blank">Available on the arXiv e-print archive</a>.
(3) "Comment on Time-Variation of Fundamental Constants". Duff, M.J. <a href="http://www.arxiv.org/abs/hep-th/0208093" target="_blank">Available on the arXiv e-print archive</a>.
(4) "A time varying speed of light as a solution to cosmological puzzles". Albrecht, Andreas and Magueijo, Joao. <a href="http://www.arxiv.org/abs/astro-ph/9811018" target="_blank">Available on the arXiv e-print archive</a>.

Here is a paper which attempts to refute (3). I provide it so that you can try to make up your own mind on this. "Comment on the Variation of Fundamental Constants". Moffat, J.W. <a href="http://www.arxiv.org/abs/hep-th/0208109" target="_blank">Available on the arXiv e-print archive</a>.