The universe may be a billion years younger than we thought | Hacker News Reader

The universe may be a billion years younger than we thought

nbcnews.com

63 pointsokket25 comments

There is actually a third way to bound the age of the universe. And that is to say that it must be older than the oldest known stars. In particular, older than https://en.wikipedia.org/wiki/HD_140283.

This star is (barely) compatible with the Plank readings. It is nowhere near a fit with the new figures. So while a lot of science has to be done to reconcile the methodologies, I'm betting that the universe doesn't wind up being a billion years younger than we thought.

If you read the paper, the age calculation reads like assumption upon assumption upon assumption upon assumption. The distance measurement is remarkable though.

Every age calculation in astronomy reads like that. Distance calculations as well.

The full story is actually (I think) more interesting than the headline suggests.

Really what we have here are two methods of calculating the age of the universe that disagree. And we are getting to a stage where the disagreement (or "tension") is fairly statistically significant (3 or 4 sigma if I remember correctly). But, if LambdaCDM is the correct model for the universe these two methods should give the same age and so the fact that they are different implies that there is more to the universe (new physics!) than LambdaCDM. This is very exciting (and imo much more exciting than a 10% change of the age of the universe)!

Of course, both sets of measurements are fantastically hard to make and so there is a chance that this disagreement is just a result of a systematic that hasn't been properly understood/controlled for... But people are starting to think this might be real.

Here's a readable summary of what's going on: https://astrobites.org/2016/08/22/the-trouble-with-h0/

I swear when the weather’s good it doesn’t look a day over 9 billion around here.

This is a really cool story. Science FTW! We have new evidence and people are starting to adjust their frame of mind and thinking in regards to the new evidence. Hopefully they can prove their hypothesis and we'll have a better idea of the actual age of the universe.

I would like to see a scattergram of the universe's estimated age over the past one hundred years just to see if we're starting to converge yet or not.

MOND, MOND, MOND…

I can believe in dark matter.

I can believe in dark energy.

I cannot believe in both…

MOND, MOND, MOND…

MOND doesn't actually get rid of dark matter, it just means you only need ~20% as much of it. If it did fix dark matter it'd very possibly be the more popular theory. The issue is that galaxies-- according to the dark matter paradigm-- don't have a precisely predictable amount of dark matter. There are galaxies that seem to have vastly different quantities of dark matter than other galaxies that despite the fact that their ordinary mass distribution looks very similar. That is, different galaxies need different amounts of correction from Newtonian Dynamics in ways that are seemingly random, and therefore cannot be incorporated into MOND. So you still need some dark matter to fix this problem.

This has always felt a little wrong to my layman mind. It’s like saying 4+2=7. Oh it doesn’t match? Well, invent some magic stuff to fix the difference (4+2+magic=7) so we don’t have to change what we believe. I guess I don’t understand why it’s not easier to doubt what we think we know than invent something we don’t have evidence for. Is dark matter’s existence a settled thing?

I am also a layman, but I'll take a stab at it.

Here's a galaxy with a certain amount of mass, distributed a certain way. It has a certain rotational velocity (as a function of radius from the center).

Here's a different galaxy that has just about the same mass and mass distribution, but it has a different rotational velocity. That leaves a very few options:

- Our measurements are wrong.

- Rotational velocity is not a function of mass.

- Or, there's more mass than we can see.

People have carefully checked the first, but it's still possible. The second seems really weird: Rotational velocity depends on mass plus the roll of 2d6?!? That leaves dark matter as the explanation that seems the most reasonable.

Aren’t the first and third the same thing - we didn’t measure it all?

To just invent something that can’t be explained to make us feel better sounds a whole lot like religion.

[edit] Also, thank you for your reply. It helps

One is, either we didn't correctly measure the mass (which we measure by the light emitted), or we didn't measure the rotational velocity correctly (which we measure by doppler differences between the different sides of the galaxy).

The third is that there is mass that doesn't emit light at all. (I think it's a bit stronger than that. I think that they think that it doesn't interact with light at all, not just not emit it. But I forget how they think they know that, and I'm not certain that they think they know it at all.)

> To just invent something that can’t be explained to make us feel better sounds a whole lot like religion.

They don't invent it to make themselves feel better. They invent it so their equations work. (Of course, they feel better when their equations work...)

Dark matter doesn’t interact with any of the forces other than gravity and possibly the weak force.

Not interacting with the electromagnetic force is the same thing as not emitting light.

But this also means that DM cannot be cold baryonic matter.

MOND or any other modifications of Newtonian Gravity or GR aren’t random.

In the case of MOND (and TEVES) Gravity is modified but it’s modified in a manner that is consistent with both macro and micro observations it’s not adding a random dice throw.

The reason why people went after MOND and the rest is that Newtonian Gravity is surprisingly accurate even without using PPN.

Now the big problem with MOND and most of the other modifications is the speed of gravitational waves that pretty much shut down much of the discussion.

That said I’m not entirely sure they had the wrong idea at this point I think it’s more likely we don’t understand something about gravity or space time than there is a new class of matter out there.

That said the fact that we have both found clusters which apparently more dark matter than usual and those which seem to completely lack DM is still a good reason to continue searching for DM.

However I really don’t like how MOND proponents were treated especially pre-LIGO.

You sound like a cheerleader. But science isn't done by seeing which side cheers loudest...

I am reminded of the Steady State model of cosmology. It was a contestant to the Big Bang theory, appearing cleaner and somewhat more sensible. Go read up on it, it relies on a really neat principle.

But we all know how this turned out: Overwhelmingly data supported Big Bang, and Steady State is now just an episode in science history.

So while I really like MOND and wish for it to be the answer, I won’t be surprised if it’s not.

This abstract, "Newtonian explanation of galaxy rotation curves based on distribution of baryonic matter" uses an argument (not DM or MOND) I've not seen before. https://arxiv.org/abs/1406.2401

(It says that 'A large number of likely galaxy mass distribution profiles should in fact produce flat or accelerating rotation curves similar to those observed in reality.')

Older (2007) abstract: Kepler's third law (works for the solar system) might not apply because of galactic mass distribution. http://www.marmet.org/cosmology/nonkeplerian/galaxy.html

Five years old; didn't get a chance to find a counter-argument, but worth mentioning.

It's quite silly being surprised by inaccuracies in measuring the age of the universe by dead reckoning from some "ether" background radiation.

"More shocking, Hubble found that the farther away the galaxies are, the faster they're moving apart."

Like really? Shocking? Relative fast moving galaxies are further away than the ones with slow relative velocity by the time of measurement?

I feel the hunt for astonishing publications are to blame for all the hullabaloo.

That's not what's happening according to the article:

"Given the stakes, everyone involved is checking and rechecking their results for possible sources of error. Increasingly, though, it looks like the problem lies not with the observations but with the theories of cosmology that underpin them. If those theories are wrong or incomplete, the interpretation of the Planck readings will be flawed, too."

Ye, the reevaluation of prior result is a sign of good science and should be of greater prestige (i.e. more grant money) among researchers. There is a science wide bias for interesting results.

The same article also writes "Then came an unexpected turn of events" when another researcher disagrees to some degree, which is in no way unexpected.

This movement of galaxies was shocking when it was discovered ... in the 1920s.

It's surely not "some ´ether´ background radiation" but CMB:

https://en.wikipedia.org/wiki/Cosmic_microwave_background

And it gives us extremely precise information about the earliest times of the Universe, as well as about the whole structure of it. The scientific results from its models and results are indisputable for decades already:

https://en.wikipedia.org/wiki/Cosmic_Background_Explorer#Bla...

What's happening now is much more complicated story: there are two basic approaches to measure how old the Universe is, we know anyway that it's more than 12 billions of years, but they differ and the difference is less than 10 percent (i.e. around a billion years). One of these approaches depends on the CMB measurements. The other is this one from the article to which we all comment. The scientists hope that they can learn something new even from that less than 10 percent difference. But that won't invalidate the existing measurements, or make anything "completely wrong" it can only lead to some adjustments of the existing models:

https://www.forbes.com/sites/startswithabang/2019/05/03/cosm...

Edit: re "how the scientists know it's not noise" -- CMB was estimated some 70 years ago and measured 60 years ago, for 60 years all the scientists of the world were able to check and recheck and effectively nobody can seriously dispute it. Different careful measurements by the satellites only improved the picture, and confirmed the predictions beyond any doubt (one of those I've already given). There's an article about CMB's discovery in Wikipedia, of course: https://en.wikipedia.org/wiki/Discovery_of_cosmic_microwave_...

The most interesting point is: CMB doesn't behave like noise would. It has so called "blackbody spectrum" which in common speak means its spectrum has very specific shape, that nothing that is not thermal by nature would have.

https://wmap.gsfc.nasa.gov/universe/bb_tests_cmb.html

So we know that the Universe was around 270 millions degrees hot at the moment this radiation was produced! Then the Universe expanded for billions of years which lowered the temperature of the CMB and now its temperature is only 2.7 degrees above absolute zero! The "noise" would not have such curve, and COBE mission was the first to measure and confirm it, it was amazingly good fit to the predictions, all following satellites produced even better results. It's one of the most impressive fits to the scientific predictions ever.

Note that the Wikipedia article writes:

"The CMB is faint cosmic background radiation filling all space."

"From the CMB data it is seen that the earth appears to be moving at 368±2 km/s relative to the reference frame of the CMB"

Bantering calling that "some ´ether´ background radiation" is not that far fetched.

It would be interesting to find out how the physicist distinguish CMB from noise in their equipment.

I've edited my previous message to give you a story about the difference from noise. It's an amazing story.

But it seems there are some readers still attracted to your answer, even if it's nonsensical. I'll prove now that claim of mine, that your answer above has no sense: you specifically quote:

"From the CMB data it is seen that the earth appears to be moving at 368±2 km/s relative to the reference frame of the CMB"

while defending you considering CMB to be 'ether' as this speed information could somehow confirm what you write.

But you can't cherry pick the scientific results like that: It's not a car in which you "just read the speedometer." For you to believe in that speed result which you quote you'd have to believe the formulas for the CMB are right, as the speed is the result of the application of the formulas. So either you believe in the formulas, quote the speed and simply can't call CMB 'ether', because the formulas are based on it not being and behaving as that, or you don't believe in the formulas, but then you are rejecting all the related science of last approximately 100 years, checked and verified unbelievably many times, and you also at the same time can't use the speed as a confirmation of anything you write. In both of these two possible cases your response is nonsensical as it contradicts itself in both cases from one sentence to another.

Reply on news.ycombinator.com