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buybuydandavis comments on Some recent evidence against the Big Bang - Less Wrong
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The way I see it is this:
Theory A. Light travels to infinity without losing light
Observation 1. Light redshifts and does not seem to travel to infinity
Theory B. The galaxies are receding, redshifting the light
Theory C. Since theory B puts us at the center of reality, let's make it so space is expanding
Theory D. If space is expanding, in the past it was smaller, and there was a beginning of time
Observation 2. The horizon problem.
Theory E. Everything interacted with everything, then hyper-expanded, then stopped hyper expanding
(skip some steps)
Theory M: Dark energy did it
(skip some steps)
Theory T: In the multiverse, any thing can happen, even different laws of physics (that makes the multiverse of inflation way different than Everettian QM, which operates on the wave equation), and an infinite number of universes are made, and ours happens to do this cool dark energy inflation stuff
Observation 3: BICEP2 found dust.
What I'm questioning Theory A.
Theory A says light travels forever, which was established in the 1800's before we knew there were galaxies other than the Milky Way, before we detected redshift.
We observe a finite amount of light from a finite distances.
That's an empirical fact.
That is to say, the empirical and theoretical range of electromagnetic radiation are not in agreement.
The articles I post cast great doubts over the CMB being what it is claimed to be, the existence of a "young universe", the nucleosynthesis, and the growing skepticism over the scientific value of inflation.
What else does the Big Bang have to rest on?
"Is there a better theory?"
Take Hubble's Law, v = H * D where v is the apparent recessional of velocity of a galaxy at distance D, and H is Hubble's Parameter. If the apparent recessional velocity is only apparent, and not actual, we could actually take that term (H * D) from the distant galaxy (such that its v = 0) and say put it into the frequency (f) of the photon f = (c - H * D) / w where w is the wavelength from which it was emitted.
In this theory, redshift is a feature of light itself.
I know this lends itself to many criticisms and open questions, however, no one has provided Dark Energy, and supposedly it makes up 68% of the observable universe, which doesn't seem consistent with observation.
Here's something else I found, when looking into it:
— E. Hubble, Monthly Notices of the Royal Astronomical Society, 97, 506, 1936
I also found that the temperature of space was predicted to be 3K by Aurthor Eddington in 1926. The Big Bang's predictions where nowhere near that, and when the CMB was discovered in the 60's at 3K, the discovery was claimed to be evidence of an expanding universe.
If cosmology is why computers worked or airplanes flew, or was ever corroborated by a lab experiment, then I probably wouldn't be questioning. But it takes places millions of light years away, millions of years ago. And the experts in the articles I cited were calling it into question.
Is there a cognitive bias to have a creation myth?
Hey, another crazy person like me. Now we are two.
I've had a similar take on it for a long time. It seems like the expansion is an attempt to explain observed red shifts, necessitating an increasingly convoluted theory to explain other observations.
The observation is, the farther away, the greater the shift, in a linear fashion.
f=f_0 - D*Constant
What if it light just loses energy as it travels, so that the frequency shifts lower?
That seems like a perfectly natural solution. How do we know it isn't true?
What would be the implications to the current theories if it were true?
This class of theory goes by the name of "Tired light". It seems as if every theory of this kind precise enough to make definite predictions has been pretty clearly falsified, but I'm not an expert on this stuff.
A relation of the form f = f0 - constant*distance will send the frequency to zero (and then out the other side) once the distances get large enough. You probably don't want that.
In the limit, yes. I have no prior that says this is a problem.
Also, as one approaches such a limit, I wouldn't be surprised to see other terms come into play.
Note that no actual infinite limits are required. Just large but finite distances.
I think you should have. One of three problems, depending on what you expect to happen. (1) If you expect something more complicated to happen for large distances, your theory is more complicated than it initially looks. Doesn't your prior favour simpler theories? (2) If you expect the frequency to pass through zero and continue, your theory will have to (2a) explain what negative frequencies actually mean, why frequency -f isn't just the same as frequency +f with different phase, why we never see anything with negative frequency, etc., or else (2b) if instead it says that negative frequencies are the same as positive, then explain what happens to the frequency after it crosses zero (gets more negative? then -f isn't the same as +f after all. gets less negative? then what we actually end up is a really weird discontinuity at the zero crossing). Again, all this stuff is extra complexity. (3) If you expect the issue not to arise because nature somehow ensures that light never travels far enough for the frequency to reach zero, then your theory needs to explain how that happens. Extra complexity again.
This sounds like case 1 above.
I expect infinite complexity, but pick the simplest model to account for the currently known data. Keep on expanding the range of applicability, and I expect to see new effects that aren't accounted for in models validated over a more restricted range of data.
Reality is more complicated than it looks, and I don't expect that to end.
No, I don't expect negative frequencies, as frequency goes down, energy goes down, and I expect quantum effects to take hold as energy approaches zero. You can call that "extra complexity", but we already know there are quantum effects in general.
OK. Does that stop you regarding a theory as more credible when it's simpler (for equal fidelity to observed evidence)?
Everything is quantum effects. Do you have more specific expectations?
It's more credible in the range of data for which it's fidelity has shown it to be more credible. I expect extrapolations outside that range to have less fidelity.
No.
I don't have some grand unified theory.
I just observe that a lot of cosmology seems to be riding on the theory that the red shift is caused by an expanding universe.
Note that I ended my first post with questions, not with claims.
This seems wrong to be. There's at least two independent lines of evidence for the Big Bang theory besides redshifts -- isotope abundances (particularly for light elements) and the cosmic background radiation.
We would have to abandon our belief in energy conservation. And we would then wonder why energy seems to be conserved exactly in every interaction we can see. Also we would wonder why we see spontaneous redshifts not spontaneous blue shifts. Every known micro-scale physical process in the universe is reversible [1], and by the CPT theorem, we expect this to be true always. A lot would have to be wrong with our notions of physics to have light "just lose energy."
This solution requires light from distant galaxies to behave in ways totally different from every other physical process we know about -- including physical processes in distant galaxies. It seems unnatural to say "the redshift is explained by a totally new physical process, and this process violates a lot of natural laws that hold everywhere else."
[1] I should say, reversible assuming you also flip the charges and parities. That's irrelevant here, though, since photons are uncharged and don't have any special polarization.
Something already does happen for large distances.
That's an observable fact. It's redshift.
What causes it?
The standard answer is expansion, which needs inflation and dark energy and an arbitrary multiverse to do that. Al lthings that make the theory more complicated with distance.
Alternatively, what if light doesn't travel forever?
How would such a reality look if things existed farther away than light could travel?
Is it not exactly what is observed?
What is more complex,
0 frequency photons ceasing to be photons,
or
infinite wavelength photons everywhere never interacting with anything in space expanding faster than c?
If it's a matter of complexity, the 0 frequency photons ceasing to exist is less complex than there being infinite wavelength photons everywhere.
The thing you need to evaluate the complexity of is an actual theory, with equations and everything, not a vague suggestion that maybe photons lose energy as they travel.
I don't think the conventional theory says you have infinite-wavelength photons, and I think your thought experiment with your two hands is wrong. Light from an object at the Hubble limit not only never reaches us, but also never reaches (say) a point 1m "inward" from us. It never gets any closer to us. Note that this is not the same as saying that light from 1m less than the Hubble limit never reaches us, which of course is false.
We get arbitrarily long-wavelength photons, if we wait long enough, but we have to wait longer for the longer-wavelength ones and we would have to wait infinitely long to get ones of infinite wavelength.
As gjm mentions, the general name for this sort of theory is "tired light." And these theories have been studied extensively and they are broken.
We have a very accurate, very well-tested theory that describes the way photons behave, quantum electrodynamics. It predicts that photons in the vacuum have a constant frequency and don't suddenly vanish. Nor do photons have any sort of internal "clock" for how long they have been propagating. As near as I can tell, any sort of tired light model means giving up QED in fairly fundamental ways, and the evidentiary bar to overturn that theory is very high.
Worse, tired light seems to break local energy conservation. If photons just vanish or spontaneously redshift, where does the energy go?
I can conceive of there being a tired light model that isn't ruled out by experiment, but I would like to see that theory before I junk all of 20th century cosmology and fundamental physics.
Most scientific theories, most of the time, have a whole bunch of quirky observations that they don't explain well. Mostly these anomalies gradually go away as people find bugs in the experiments, or take into account various effects they hadn't considered. The astronomical anomalies you point to don't seem remotely problematic enough to give up on modern physics.
The test between an expanding model is and not expanding model is the Tolman Surface Brightness test.
It seems the expanding models predict an exponent of dimming 4, that is (1+z)^4.
A non expanding model would be an exponent of 1.
You could also make a model with frequency and energy decreasing because the speed of a photon is v = c - H * D.
In that case the trip the photon takes through static space is equal to the duration of the same trip through expanding space. In this case, the exponent predicted is 3 (it loses 1 exponent since the rate of photons stays constant instead of decreasing).
The actual Tolman Surface Brightness test seems to yield an exponent of 3.
or rather an exponent of 2.6 to 3.3 depending on frequency range.
http://en.wikipedia.org/wiki/Tolman_surface_brightness_test
but another explanation to the one given on wikipedia is that the universe is not expanding but has another geometry (again source: crackpot).
Under the assumption that photons don't lose energy as they travel, right?
The speed? You're modeling a change in speed by distance traveled?
Because the mathematics looks the same, would this be the same exponent for a model with:
In the expanding model, there are four factors of (1+z). 1 for the decrease in energy, 1 for the reduced rate at which photons arrive, and 2 for the increased trip of the photons through space.
In a static model, let's say tired light from the 1930's, light still always traveled at c and never lost energy on its own, it was thought maybe it hit dust. The dust makes the pictures blurry, which would be observed, so tired light (1930's) is ruled out.
What you and I seem to think is possible is almost always instantly called tired light and dismissed from mind, despite being different models.
The (1930's) tired light model has static space, and a photon always moving at c. It loses its energy via the hypothetical dust interactions and that's one factor of dimming. There are three missing.
Now consider a model where the photon's speed is c - H * d. In this model, the energy decreases, and the time it takes for a photon to make the journey increases with distance.
In other words, in "tired car" model (analog to 1930's tired light), it takes a car traveling at 60 mpg an hour to travel to a location 60 miles away.
Then there is the standard model, call it "expanding road". The car still travels at 60 mph, but the destination is receding away. Therefore, the trip is longer than hour.
Now, a novel model, the finite car model. Unlike the other models, the car itself can't travel to infinity. The road isn't expanding and the destination stays put, nothing gets in its way, but the car doesn't travel forever, it (figuratively) runs out of gas and coasts.
If its speed is 60 mph - H * D, then it will take it take longer than an hour. The same amount as if the road were expanding.
Now imagine, you had 1000 of these cars, and you sent a new one toward the destination every 10 minutes.
If the road is not expanding, and the car is coasting it, each car coasts in 10 minutes apart. This model has 3 factors of (1+z).
If the road were expanding, the cars would reach the destination at increasingly larger intervals. The rate of their arrival is the 4th dimming factor.
An AskScienceDiscussion question I asked to verify this
We have slightly different models. You've obviously put more thought into yours, but I still like mine better, though I entirely admit I haven't studied the implications of either.
Your model challenges two fundamental assumptions, and mine only does one.
For my model, the speed of light remains constant, but the energy of the photon decreases as it travels. A photon is a car fueled with itself, slowly burning itself up, though I'm not committed to it entirely burning itself up in the limit.
I wouldn't think this would have anything to do with "dust". Just travel through free space. I'm not explaining the effect, which I'd guess would require general relativity, just noting it as a possible mechanism for the observed red shift.
La Wik:
Sounds about right to me.
Does it go somewhere or you're discarding the Conservation of Energy?
Exchange of momentum with the gravitational field?
I don't understand this sentence. Do you want to say that light going through the gravitational field makes the gravity stronger..?
Sounds like Dan Davis means "turns into gravitons".
It might be interesting to consider the physics world at about 1935, and then again at 1945.
I heard one narrative put it in such a way, that these discoveries of galaxies and lots of them far away had quite a bit of interest, until everyone's focus became war machines and nuclear bombs. When they returned to cosmology after the war, it was as they "said, where were we, space was expanding? ok" and then proceeded to work from there. An oversimplification I'm sure.
By the way. That is one effect of the crackpot theory I posted below. Only it doesn't 'lose energy'. It kind of spreads it over a complex time component (thus geometrically the energy isn't lost) only in our real projection of the time component it appears to be so.