I don't think space is expanding.

[Mike Helland]

Cosmology seems to be getting a lot of press these days. And not really good press.

Just search for cosmology and news, and you'll see things like "crisis" and "new physics".

The gist is the best new measurements of the expansion of space disagree. Either 74 or 64.7.

Here's my take.

Imagine you're jogging down the road and every block you pass you look at your watch, and every block takes 2 minutes.

Then one day you run farther than normal, as you go, you notice that it takes 2:03 to run a block, then 2:10, then 2:29.

Clearly, the blocks far away from your house seem to be growing!

What makes them grow? Dark forces!

Obviously, that's not the case, you're just slowing down. Blocks aren't expanding. You're just not running as fast as when you started.

But imagine it's 1930, and relativity is really new and really cool. And galaxies are also really new and really cool.

And we're not talking about a jogger, we're talking about light.

Light travels to infinity forever at c. Relativity says so.

Or..... maybe it doesn't. At least, not for infinity it doesn't.

The speed of a wave of frequency x wavelength.

Redshift is an observed drop in frequency.

Take literally.... redshift would lead to a drop in frequency

I make a hypothesis based on this:

v_photon = c - H * D

It's basically Hubble's Law, but moved to the speed of a photon, instead of the speed of a galaxy.

I also found that this version of Hubble's law is slightly different than the standard model, in that it predicts less expansion at the extreme end of the observable range, which is what we see with the Hubble tension.

 

[Myriad]

That's called a "tired-light" hypothesis, and they've been around since the redshift was first observed. When I was young there was still a considerable amount of discussion about them, though they had already fallen pretty far out of favor.

Tired-light theories don't match observations well. Redshift caused by relative motion reduces the surface brightness of a distant body more than redshift caused by light slowing down alone. (The first dims the energy of each photon and also slows down the apparent rate of photons being emitted due to time dilation; tired light would have only the first effect.) Brightness measurements are more consistent with relative motion.

Other observations such as the duration of supernova events are also consistent with increasing time dilation with increasing distance (that is, expansion) and not with distance alone.

ETA: There's also the little matter of the cosmic microwave background. That could be very tired light, maybe, but tired light from what? It couldn't be from a big bang, if there's been no expansion.

 

[Ziggurat]

ETA: There's also the little matter of the cosmic microwave background. That could be very tired light, maybe, but tired light from what? It couldn't be from a big bang, if there's been no expansion.

The CMB is a real puzzle for anyone wanting some alternative cosmology. It’s actually quite hard for most people to understand why it’s so remarkable. The absolutely perfect blackbody shape of the CMB spectrum is something we can’t even produce artificially.

 

[Mike Helland]

That's called a "tired-light" hypothesis, and they've been around since the redshift was first observed. When I was young there was still a considerable amount of discussion about them, though they had already fallen pretty far out of favor.

Yeah, this is a novel version of tired light with varying speed of light mixed in.

Tired-light theories don't match observations well. Redshift caused by relative motion reduces the surface brightness of a distant body more than redshift caused by light slowing down alone. (The first dims the energy of each photon and also slows down the apparent rate of photons being emitted due to time dilation; tired light would have only the first effect.) Brightness measurements are more consistent with relative motion.

This seems pretty relevant, but doesn't seem to be all that well followed up in science.

According to the wikipedia on Tolman Surface Brightness test:

"The exponent found is not 4 as expected in the simplest expanding model, but 2.6 or 3.4, depending on the frequency band."

What's up with that?

Other observations such as the duration of supernova events are also consistent with increasing time dilation with increasing distance (that is, expansion) and not with distance alone.

I'm certainly familiar with that one too.

If you look up "Supernovae Light Curves: An Argument for a New Distance Modulus" by Jerry Jensen, he says those supernovae are bigger because of a "Malquist type II" bias.

Not much follow up on that one either.

I'm not trying to ignore these findings, but it's also true that the standard model is running sideways with plenty of observations, and that's after the patchwork of inflation and dark energy and matter they're got going on.

ETA: There's also the little matter of the cosmic microwave background. That could be very tired light, maybe, but tired light from what? It couldn't be from a big bang, if there's been no expansion.

It could just be light from a universe that stretches out trillions of light years, well beyond Hubble's limit.

The CMB also shows us a cold spot to the south, which runs counter to current standard models, but not an indefinite universe.

 

[Mike Helland]

If the CMB is just light coming in at the edges of its physical limits (Hubble Length), then of course it wouldn't reflect any light.

Alternative cosmologies can deal with the anomalies in the CMB, like the cold spot and the slightly cooler northern hemisphere, better than the standard model.

 

[Ziggurat]

It could just be light from a universe that stretches out trillions of light years, well beyond Hubble's limit.

No, it could not. There are no other significant sources of light in the universe which present a perfect blackbody spectrum.

If the CMB is just light coming in at the edges of its physical limits (Hubble Length), then of course it wouldn't reflect any light.

You seem confused about what a blackbody spectrum actually is. No shame in that, it's actually not a simple thing. Thermodynamics is not an easy subject*, and even seemingly simple concepts like temperature are much more complex and strange than they initially seem. But your theory can't turn ordinary stars into blackbody emitters.

Alternative cosmologies can deal with the anomalies in the CMB, like the cold spot and the slightly cooler northern hemisphere, better than the standard model.

No, they cannot handle it better. None of them can handle the perfect blackbody spectrum, and that's a much more significant fact than the extremely minor variations of temperature within that perfect spectrum. They may have adjustable parameters that can be tuned to produce variations, but none of that matters if the basic shape isn't even close.

As I said:

The CMB is a real puzzle for anyone wanting some alternative cosmology. It’s actually quite hard for most people to understand why it’s so remarkable. The absolutely perfect blackbody shape of the CMB spectrum is something we can’t even produce artificially.

*Trivia: one of the best introductions to any textbook comes from a thermodynamics textbook, and reads as follows.

Ludwig Boltzmann, who spent much of his life studying statistical mechanics, died in 1906, by his own hand. Paul Ehrenfest, carrying on the work, died similarly in 1933. Now it is our turn to study statistical mechanics.

Perhaps it will be wise to approach the subject cautiously.

 

[Little 10 Toes]

Op has his own thread over at cosmoquest against the mainstream

 

[Mike Helland]

If the CMB is just the temperature of space, it's not a body at all.

Therefore it reflects nothing. Perfect black body.

 

[abaddon]

If the CMB is just the temperature of space, it's not a body at all.

Therefore it reflects nothing. Perfect black body.

Space doesn't have a temperature.

 

[theprestige]

Op has his own thread over at cosmoquest against the mainstream

Where ATM theories go to die get bullied for a few weeks before they're kicked out of the clubhouse.

 

[Ziggurat]

If the CMB is just the temperature of space, it's not a body at all.

Therefore it reflects nothing. Perfect black body.

No. Space itself is not a black body. A black body isn’t defined by what it doesn’t reflect, but by what it absorbs, and space absorbs nothing.

I don’t mean to sound insulting, but it’s clear you don’t understand thermodynamics. Again, no shame in that, most people don’t. But because you don’t, you should approach the subject with a bit more humility.

 

[RecoveringYuppy]

Space doesn't have a temperature.

Not a terribly helpful comment. Plenty of accurate and knowledgeable sources refer to the CMB as the temperature of space.

 

[Mike Helland]

Not a terribly helpful comment. Plenty of accurate and knowledgeable sources refer to the CMB as the temperature of space.

Also, the temperature of space was predicted by Arthur Eddington to be 3K before the Big Bang theory was even a thing.

This prediction is more accurate than the predictions based on the CMB.

 

[Mike Helland]

A black body isn’t defined by what it doesn’t reflect, but by what it absorbs

We know what it absorbs based on what it reflects.

 

[Mike Helland]

Where ATM theories go to die get bullied for a few weeks before they're kicked out of the clubhouse.

Surprisingly, it's kind of quiet.

 

[theprestige]

Not a terribly helpful comment. Plenty of accurate and knowledgeable sources refer to the CMB as the temperature of space.

That seems neither knowledgeable nor accurate. Except perhaps in a "lies to children" context? But lies to children are not a good basis for advancing the discipline of cosmology.

 

[RecoveringYuppy]

This prediction is more accurate than the predictions based on the CMB.

That doesn't make any sense. The prediction can't be more accurate than the thing it's predicting.

 

[Ziggurat]

Space doesn't have a temperature.

To expand on what RY said, you can define a temperature for space on the basis of electromagnetic radiation within it. The space inside a sealed container will then come to thermal equilibrium with that container. The problem with what Mike said isn't assigning a temperature to space, but describing it as a black body. A black body is not defined by its reflectivity, but by its absorptivity.

This may seem at first glance to be an irrelevant distinction, since in many cases, light must either be absorbed or reflected, so that absorptivity and reflectivity can have a 1-to-1 correspondence. But the difference is crucial, because that correspondence doesn't always hold. There is in fact a third option: transmission, as happens in transparent materials. So glass, for example, can transmit light, and thus neither reflect nor absorb it. Thus, our choice of absorption or reflection for defining a black body is not a mere technicality, but is crucially important.

And the only way to define a black body in a way that makes sense, from a thermodynamics point of view, is on the basis of absorption, NOT reflection, because it is absorption, not reflection or any converse of reflection, which must be balanced with emission in order for thermal equilibrium to be possible. So perfectly transparent things are, like perfectly reflective things, the opposite of black bodies. They have zero emissivity. And space is the most perfectly transparent thing that can exist.

Long story short: space itself cannot be the source of the CMB, even if we use it to define the temperature of space.

 

[Ziggurat]

We know what it absorbs based on what it reflects.

No. You forgot transmission. See my previous post. Space neither absorbs nor reflects, because it transmits. And since it absorbs nothing, it emits nothing.

 

[Ziggurat]

Also, the temperature of space was predicted by Arthur Eddington to be 3K before the Big Bang theory was even a thing.

This prediction is more accurate than the predictions based on the CMB.

Wrong again. Eddington's prediction may have gotten the temperature roughly correct, but he got the spectrum completely wrong. He thought it would be the spectrum of starlight, which is peaked in the visible, NOT the microwave. That's about as far off as possible.

And as I said before, the critical feature of the CMB is not its temperature, but the shape of the spectrum. The temperature changes as the universe expands, so it is not constant in time. But the shape is. It remains a perfect blackbody shape in perpetuity. The Big Bang theory predicts that shape. You need additional inputs (such as the age of the universe and how fast it's expanding) in order to get the temperature, and those things are not easy to measure, so getting that wrong in the beginning is no big deal. But the shape, well, the shape is everything. BBT got it right from the very beginning. Eddington got it wrong.

I told you the shape was the key, but you still don't actually understand.