Is the Universe older than we think?

[TheOrionNebula]

TL;DR Summary

Is the Universe older than we think - or are the distance / look back times / redshift estimates from the James Webb Space Telescope (JWST) systematically biassed?

The James Webb Space Telescope, JWST, has revolutionised our views of galaxy formation in the early universe, suggesting that galaxies showing structure may have been formed at much earlier times than our best models of galaxy evolution predict. This has even led to suggestions that The Universe may be much older than we have believed (https://www.space.com/james-webb-space-telescope-evolved-galaxy-early-universe)

Yet others have suggested that JWST’s estimates of the distances, or the look back times to objects in the very distant Universe are affected by systematic biases (https://www.nature.com/articles/s41550-023-02093-8) , for example the well known Malmqvist bias (https://en.wikipedia.org/wiki/Malmquist_bias).

What do you think … could our galaxy evolution models be completely wrong, or might the estimates of very distant objects now coming from the JWST be systematically over estimated, or is there even some other effect or new Physics that is causing this conundrum in contemporary astrophysics?

 

[berkeman]

Thread closed temporarily for Moderation...

EDIT -- thread reopened provisionally...

 

[Nugatory]

TL;DR Summary: Is the Universe older than we think - or are the distance / look back times / redshift estimates from the James Webb Space Telescope (JWST) systematically biassed?

This situation is reminescent of OPERA's observation of faster-than-light neutrinos: either a) everything we know is wrong; or b) there is something wrong with the observations or our interpretation of them.

History says that although the former cannot be excluded, chances are that it's the latter.

 

[Vanadium 50]

Is the universe older than we think?
I think so.

If this were a 1960's SciFi show, at this point the computer would start smoking and explode.

However, taking thsi result at face value, there are two possibilities:

1. The universe is older than all the other cosmological evidence points to.
2. Galaxies of this sort formed earlier than we thought.

Take your pick.

 

[PeterDonis]

Moderator's note: An off topic subthread started by a now banned member has been deleted. Thread remains open.

 

[Tanelorn]

NASA's Wilkinson Microwave Anisotropy Probe (WMAP) project's nine-year data release in 2012 estimated the age of the universe to be (13.772±0.059)×109 years (13.772 billion years, with an uncertainty of plus or minus 59 million years).

This age is based on the assumption that the project's underlying model is correct; other methods of estimating the age of the universe could give different ages. Assuming an extra background of relativistic particles, for example, can enlarge the error bars of the WMAP constraint by one order of magnitude.[27]

This measurement is made by using the location of the first acoustic peak in the microwave background power spectrum to determine the size of the decoupling surface (size of the universe at the time of recombination). The light travel time to this surface (depending on the geometry used) yields a reliable age for the universe. Assuming the validity of the models used to determine this age, the residual accuracy yields a margin of error near one per cent.

In 2018, the Planck Collaboration updated its estimate for the age of the universe to 13.787±0.020 billion years.

In summary the age of the Universe is based on CMBR measurements.

However, one thing I have been curious about is whether relativistic time dilation is included in the age of the universe numbers? A year back then is longer than a year now:
https://www.space.com/quasar-clocks-universe-time-dilation

 

[Ibix]

A year back then is longer than a year now:

No it wasn't, and the article is very misleading. What the study referred to showed was that clock-like processes in quasars appear slowed by exactly the same factor as the cosmological redshift of light from the same source. So it shows that there's nothing going on except cosmological refshift, and it's yet another nail in the coffin of alternative redshift theories like "tired light".

 

[TheOrionNebula]

TL;DR Summary: Is the Universe older than we think - or are the distance / look back times / redshift estimates from the James Webb Space Telescope (JWST) systematically biassed?

The James Webb Space Telescope, JWST, has revolutionised our views of galaxy formation in the early universe, suggesting that galaxies showing structure may have been formed at much earlier times than our best models of galaxy evolution predict. This has even led to suggestions that The Universe may be much older than we have believed (https://www.space.com/james-webb-space-telescope-evolved-galaxy-early-universe)

Yet others have suggested that JWST’s estimates of the distances, or the look back times to objects in the very distant Universe are affected by systematic biases (https://www.nature.com/articles/s41550-023-02093-8) , for example the well known Malmqvist bias (https://en.wikipedia.org/wiki/Malmquist_bias).

What do you think … could our galaxy evolution models be completely wrong, or might the estimates of very distant objects now coming from the JWST be systematically over estimated, or is there even some other effect or new Physics that is causing this conundrum in contemporary astrophysics?

Good question. However, the estimated age of the universe from the WMAP data does include the effects of relativistic time dilation, although probably not in the way that you think! The calculations that lead to the age estimate are based on the ΛCDM model, which already uses general relativity to describe the expansion of the universe. Therefore, the age of 13.772 billion years already accounts for how time and space have evolved since the Big Bang, incorporating the relativistic effects that influence our understanding of time and distance in the universe. It is however interesting to note that at a discussion meeting at The Royal Society in London last month, there were a number of threads shown that have pointed to some possible discrepancies in current understanding of ΛCDM - but for the moment it is as good as we currently have.

 

[Drakkith]

Good question.

You are answering your own question.

 

[Tanelorn]

Thanks Ibix. I believe that it is true that a clock in orbit close to a Black Hole is slower than here on earth. So would the higher density of the universe at the time of the last scattering have any effect at all on time duration and the age of the Universe. By that I mean even a tiny fraction of a percent.

 

[Ibix]

I believe that it is true that a clock in orbit close to a Black Hole is slower than here on earth.

Yes. You don't even need a black hole - the GPS satellite clocks are deliberately broken to tick in sync with clocks stationary at ground level, not at their natural rate to compensate for this phenomenon.

So would the higher density of the universe at the time of the last scattering have any effect at all on time duration and the age of the Universe.

How would you even compare a clock now to a clock in the past? There's a concrete meaning to "which clock is faster" in the black hole case because each clock can watch the other and send signals to the other. There's no such meaning to comparing one clock now to one clock in the past - only one can watch the other and only one can signal the other. So "did time go slower in the past" is not a question with a meaningful answer.

 

[Tanelorn]

But aren't both experiments/situations hypothetical though? (noted about the GPS)
The speed of light is a constant, so I guess if it has any effect at all it would be on the wavelength of the light at last scattering. i.e. ~ 1.5 x 10-6 m.

 

[Ibix]

But aren't both experiments/situations hypothetical though? (noted about the GPS)

No. As I said, and you said you'd noted, we've done the experiment with a gravitational field. The GPS tests it every minute of every day. The original test was the Pound-Rebka experiment.

On the other hand, with regard to "time goes slower in the early universe", I challenge you to come up with an experiment that could test it. How are you going to compare the tick rates of two clocks that are billions of years apart? If you can't come up with such an experiment then your question isn't well-posed enough to answer.

The speed of light is a constant

Care is needed with this statement. $c$ is a defined constant and you will always measure light in vacuum passing you at that speed, but in curved spacetime you can't always define "speed" over long distances in a non-arbitrary way, with the result that the speed of light in general may not be $c$.

 

[Jaime Rudas]

Thanks Ibix. I believe that it is true that a clock in orbit close to a Black Hole is slower than here on earth. So would the higher density of the universe at the time of the last scattering have any effect at all on time duration and the age of the Universe. By that I mean even a tiny fraction of a percent.

I think that the situation of a clock in orbit around a massive object is very different from that of a clock immersed in a homogeneous universe.
Is the rate of a clock immersed in a perfectly homogeneous, less dense medium different from that of a clock immersed in a denser medium? I would think not.

 

[Ibix]

Is the rate of a clock immersed in a perfectly homogeneous, less dense medium different from that of a clock immersed in a denser medium? I would think not.

I can't think of a way to do a meaningful comparison.

 

[Mordred]

Thanks Ibix. I believe that it is true that a clock in orbit close to a Black Hole is slower than here on earth. So would the higher density of the universe at the time of the last scattering have any effect at all on time duration and the age of the Universe.

Consider the following two cases.

The BH scenario the mass distribution is locally anistropic. So time dilation occurs in this case
Case 2
At z=1100 surface of last scattering this isn't the case. The mass distribution is homogeneous and isotropic (essentially uniformly distributed in mass density.) So you wouldn't get time dilation due to mass distribution.

 

[Tanelorn]

I agree, I should have added in a vacuum. There are refraction effects and the apparent speed of light due to bending of space affecting photon distance travelled.
However, does the higher density of the universe back then come into play at all in terms of time dilation effects? Even the GPS in orbit needs to be accounted for.

I just saw both your replies whilst writing this, so I guess the conclusion is there is no time dilation effect at all.

 

[Ibix]

However, does the higher density of the universe back then come into play at all in terms of time dilation effects?

I repeat again: how could you compare the rates of two clocks billions of years apart? If you can't compare them, how can you meaningfully answer if one is ticking faster than the other?

 

[Jaime Rudas]

I can't think of a way to do a meaningful comparison.

Perhaps the situation would be similar to a clock at the center of mass of a gas cloud compared to that of another clock at the center of mass of a less dense gas cloud.

 

[Tanelorn]

I meant it hypothetically or as a thought experiment, like your BH example.
Perhaps if there were pulsars around back then? Not sure how old the oldest is.
https://spaceaustralia.com/feature/milky-ways-cosmic-clocks-pulsars

 

[Ibix]

Perhaps the situation would be similar to a clock at the center of mass of a gas cloud compared to that of another clock at the center of mass of a less dense gas cloud.

Assuming these clocks are ticking at the same time, they can exchange signals and determine which one is ticking faster or slower. But the early universe is billions of years in the past. All we can see is that light coming from the old one is redshifted, but this is explained by expansion. We cannot send a signal from both clocks to the other, which we need to be able to do.

Incidentally, density isn't the correct measure. It's the difference in gravitational potential between the two clocks, which will depend on size and density. And gravitational potential isn't definable in FLRW spacetime.

 

[Mordred]

Incidentally, density isn't the correct measure. It's the difference in gravitational potential between the two clocks, which will depend on size and density. And gravitational potential isn't definable in FLRW spacetime.

Agreed I should have referred to gravitational potential instead of density

 

[Ibix]

I meant it hypothetically or as a thought experiment, like your BH example.

But you still need to propose an actual experiment, even if you don't do it but only model it mathematically. What clocks would you put where, how would they communicate? What numbers would show that "time runs slow in the past"? There is no answer to those questions.

And the black hole example isn't really theoretical - we've done the experiment in Earth's gravitational field and we have results consistent with GR in the spacetime around black holes, so we have experimental support for the result, even if slightly indirectly.

 

[Vanadium 50]

I repeat again

He seems not to care.

It's more fun to debate a mind-blowinhg meaningless set of words than to do actual science and duscuss how you would inger something from observation.

 

[Tanelorn]

Ibix, You are using GPS measurement to show how time dilation effects would be very large near a BH which I agree with. However, this experiment could also never be carried out.
So, in a similar way can I not ask the same question as a hypothetical thought experiment and ask what would happen if an atomic clock had been placed near the location of last scattering?
I agree, I don't know how you could measure it.

Regarding Mordred's earlier reply isn't the BH and the location of last scattering examples similar and only different in distance scales and strength of local gravitational field?

 

[PeterDonis]

this experiment could also never be carried out

Why not? Sure, with our current technology and not having a black hole nearby, it's not going to happen in the near future, but there's nothing in principle that rules it out.

what would happen if an atomic clock had been placed near the location of last scattering?

What would you be trying to compare it to?

 

[PeterDonis]

isn't the BH and the location of last scattering examples similar

No. They are very, very different.

only different in distance scales and strength of local gravitational field?

No. In the BH example there is a well-defined concept of "gravitational potential" which varies by altitude above the hole's horizon.

In the last scattering example there is no well-defined concept of "gravitational potential" at all. The whole concept of "gravitational time dilation" doesn't even apply.

@Ibix has been telling you this already for some time now. I strongly suggest that you read back over his posts, carefully. This thread is going around in circles because you are not paying attention to the responses you are getting.

 

[Tanelorn]

You are all talking about measurements, which I agree cannot be made.
I am asking from a theoretical point of view.
The closest answer so far has been from Mordred. But I am still not certain that the two cases are that different.

Thanks Peter, there is no local gravitational potential so there is no time dilation effect. Got it.

 

[Ibix]

I am asking from a theoretical point of view.

But if you can't even in principle make measurements, what numbers will you put into the theory? With the black hole, I can write down the altitude of the two clocks, specify that they're hovering directly above each other, and that they will compare tick rates by exchanging light signals. I can then do calculations with the chosen altitudes and the resulting flight times of the light.

How are your clocks in the past and the present even in theory going to exchange light signals? This is the question you seem to be just hoping will go away if you repeat "theoretical" often enough. It won't. You still need an experimental setup to describe in the model. If you don't, you have nothing to describe with the theoretical model.

 

[Tanelorn]

Thanks Ibix, I will be sure to use this approach next time I speak with a theoretical Physicist!

 

[PeterDonis]

You are all talking about measurements, which I agree cannot be made.

Nobody else but you has said that measurements cannot be made.

I am asking from a theoretical point of view.

The theory is tested by making measurements and comparing the theory's predictions. It makes no sense to say "well, there is no way to ever make this measurement, but what does the theory say about it?"

 

[Tanelorn]

Peter, I am a very old engineer who faces real life practical problems every day. Putting a spaceship in orbit close to a BH is about as speculative to me as... It will never happen.
That said the Parker solar probe is doing something vaguely similar.

So no more thought experiments aye?

 

[Ibix]

Putting a spaceship in orbit close to a BH is about as speculative to me as... I doubt it will ever happen.

But the only real problem is that we don't have a black hole to hand. If we had one it would be no more difficult than any other space probe to Jupiter or whatever.

The problem with "did time run faster in the early universe" is that we can never have the early universe and the current universe side-by-side to compare clocks.

One is a purely practical problem. The other is trying to sneak around causality somehow.

 

[Tanelorn]

So therefore, in both cases, we have to rely on theory and common sense, because neither experiment is going to happen. Anyway, I am happy with Peter's answer regarding no local gravitational potential.

 

[PeterDonis]

I am a very old engineer who faces real life practical problems every day.

That's fine. But physics is not engineering.

Putting a spaceship in orbit close to a BH is about as speculative to me as... It will never happen.

But it is still permitted by the laws of physics. Exchanging light signals with a hypothetical atomic clock at the surface of last scattering is not.

no more thought experiments aye?

Thought experiments are a useful tool in physics. But you do not appear to understand how thought experiments work. They work by setting up a scenario that, however unlikely in practice, is permitted by the laws of physics.