Is Cosmic Expansion the Best Fit Model?

I have never been convinced that there was a big bang. The evidence does not seem sufficient, at least from my perspective.

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Interesting. Do you agree that expansion is occurring? What do you see as a suitable alternative that is also in line with predictions around CBR?

And, Happy First Anniversary here at PS, too… :slight_smile:

No. That’s where I see the evidence as falling short. I agree that there is redshift. And I agree that expansion would cause redshift. But I don’t see that as sufficient evidence for expansion. Maybe there is a cosmological cause of redshift that does not involve expansion.

WHAT IF it’s not expansion … trying to wrap my head around this one … if the universe is not expanding, then the frequency of light is slowing down over time … ? … and objects we think are very distant are not … possibly implying the speed of light is not constant (??) … I think any of these should have consequences that would be directly observable. Gravitation lensing would work differently, distant galaxies would be much closer together. Relativity is defenstrated.

I disagree, but it’s still fun to think about! :slight_smile:

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@nwrickert Do you see any alternatives that fit better than expansion fits?

That doesn’t follow. Maybe the frequency of light is slowing down. Or maybe our clocks are speeding up.

We have no cosmological standards for time. We have no cosmological standards for distance. All of our standard are local standards. We base them on local phenomena, and then attempt to extrapolate them to the cosmos as a whole. But maybe there isn’t a possible time metric that can be extended throughout the entire cosmos. Maybe there isn’t a possible distance metric that can be extended thoughout the entire cosmos. Maybe the cosmos is a far stranger place than we take it to be.

Whoa. A YEC could have said that, or something very similar!

Anything but having a beginning that could be misconstrued as evidence for the existence of God.

What about pulsars? Rotation rates? We have many of those and they seem consistent. We do also have standards for distance, I remember reading that the brightness of certain star types lessens at a certain rate, which is correlated to the measured distances… so we have verification there. I may not have addressed your issue correctly or described the technical issues correctly either. Hopefully one of our physicists will jump in and clear things up.

Finally, though, are you not at all convinced by the temperature of the CBR matching that of the hot big bang models so closely?

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A YEC is making strong claims. I am not making claims. I’m just watching the evidence that shows up and keeping my options open.

The use of red shift to measure distance is good science. I very much support that. I just happen to think that the big bang hypothesis takes us a bit too far from what we can infer.

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Okay, I get it… but can you see why it adds up for the rest of us? We don’t see the same problems you see with distance, time, age or speed. We haven’t stumbled upon this conclusion, it’s validated in many different ways that don’t seem to better support another model, currently, at least…

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Stephen Hawking was pretty sure that the universe had a beginning. But yes, keep your options open, by all means, while you can.

Yes. And I have no problem with that. I’m not campaigning for my view. I’m just reserving judgement for now.

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Understood… Nor was I. I really was curious as to where you were on the topic given the evidence. Thanks Neil.

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Just my two-cents:

First, Big Bang is not equivalent to the expanding Universe. One can have an expanding Universe that is not Big-Banging.

Further, the cosmological redshift is not the only evidence for expansion. For example, there are evidence based on the relative abundances of elements in the Universe, or the existence and properties of the cosmic microwave background. All of these evidence fit very nicely with the expanding universe picture. There could be theories where the Universe is not expanding that also explain all of the evidence; I don’t know of any, but I am not well read in alternative cosmology models.

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Fortunately Neil isn’t a YEC.:slight_smile:

Jason Lyle has his “One-Way Speed of Light” theory. IIRC it hits on some of the same definitions that Neil mentioned. Lyle claims that since we can only measure the 2-way speed of light (there and back), then there is no way to prove the speed of light is the same going both ways. (I’m told that) Lyle is technically correct, but in the words of Douglas Adams, “This argument isn’t worth a pair of fetid dingo’s kidneys.”

All the physical measurements we make are consistent with the “two-way” speed of light being constant. For instance, if the Universe is less than 10,000 years old, then very distant galaxies should be the same age as our own. That’s not what we see though; distant galaxies are younger, from an earlier time in the universe. If Lyle were correct then distant galaxies should appear to be the same age as our own.

Maybe not. I was speculating on assumptions and consequences.

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As I see it, science is mostly driven by measurement.

To say that the cosmos is expanding is to say that distances between objects are increasing. But we are not measuring that. Our ability to measure the distance to astronomical objects is too imprecise for us to be able to detect the kind of change that expansion claims. Instead, we are making indirect inference based on other data (such as red shifts). These indirect inferences depend on assumptions which we cannot experimentally test.

So I’m currently hesitant to make those assumptions.

Yeah, I’m familiar with Lisle’s Anisotropic Synchrony Convention. I think gravitational lensing debunks it, and several other things do as well. (And you need intelligent photons that know what direction they are traveling to decide how fast to go. :roll_eyes:)

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At least YECs recognize that they have a distant starlight problem.

Or, rather, it is to say that objects are moving apart (velocity vector pointed away), which we are measuring.

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