Astronomers reevaluate the age of the universe

[Admin]

Scientists have taken a fresh look at the observable (expanding) universe and have estimated that it is 13.77 billion years old (plus or minus 40 million years).

Astronomers reevaluate the age of the universe : Read more

 

[rod]

Interesting how the Hubble time is calculated. Measurements using the CMBR tend toward the 13.77 or 13.8 billion years mark for Hubble time. I have 11 reports now documented in my home database covering measurement differences for H0 from June 2020 through this report. H0 ranges from 66.2 km/s/Mpc to 82 km/s/Mpc, depending on what object(s) are studied. These all result in different Hubble time measurements. The cosmology calculators can be used to see how the Hubble time can be tweaked https://ned.ipac.caltech.edu/help/cosmology_calc.html

The paper here is 'The Atacama Cosmology Telescope: a measurement of the Cosmic Microwave Background power spectra at 98 and 150 GHz', https://iopscience.iop.org/article/10.1088/1475-7516/2020/12/045, "Abstract We present the temperature and polarization angular power spectra of the CMB measured by the Atacama Cosmology Telescope (ACT) from 5400 deg^2 of the 2013–2016 survey, which covers >15000 deg^2 at 98 and 150 GHz. For this analysis we adopt a blinding strategy to help avoid confirmation bias and, related to this, show numerous checks for systematic error done before unblinding. Using the likelihood for the cosmological analysis we constrain secondary sources of anisotropy and foreground emission, and derive a "CMB-only" spectrum that extends to ℓ=4000. At large angular scales, foreground emission at 150 GHz is ~1% of TT and EE within our selected regions and consistent with that found by Planck. Using the same likelihood, we obtain the cosmological parameters for ΛCDM for the ACT data alone with a prior on the optical depth of τ=0.065±0.015. ΛCDM is a good fit. The best-fit model has a reduced χ2 of 1.07 (PTE=0.07) with H0=67.9±1.5 km/s/Mpc. We show that the lensing BB signal is consistent with ΛCDM and limit the celestial EB polarization angle to ψP =−007 deg ±0.09 deg. We directly cross correlate ACT with Planck and observe generally good agreement but with some discrepancies in TE. All data on which this analysis is based will be publicly released."

 

[KC Strom]

So, everything is moving away from everything else at appx. 42 miles/second. Is this based on redshift observations? Is there any argument that we might be misinterpreting redshift data?

 

[Helio]

So, everything is moving away from everything else at appx. 42 miles/second.

But it’s per every million parsec. So at, say, 2 million parsecs, those objects are receding from us at twice that speed.

Is this based on redshift observations? Is there any argument that we might be misinterpreting redshift data?

It is redshift but, specifically, cosmological redshift, so Doppler-like. Somehow, but I doubt any one understands, space time stretches the wavelength of light as it travels.

The tired light hypothesis gave it a run but this has been discredited. Mainstream science supports the cosmological view, and there are multiple reasons to do so.

 

[sam85geo]

Informative articles; thank you. (I only wish that my space-time could expand ..... at any rate. There is so much to learn and know and seemingly so little time). Any recommendations to amateur based Cosmology texts with mathematics would be appreciated.

 

[Helio]

Any recommendations to amateur based Cosmology texts with mathematics would be appreciated.

The “Big Bang” books will give you a good start before going deeper into math. There are online courses as well (Coursera). I learned a lot by forum discussions.

 

[KC Strom]

Thanks. The concept is challenging to me. The methodology used to determine/validate the Hubble Constant is itself seemingly variable and, seemingly, under debate. Using something variable/debatable as a constant is where I lose it. I struggle with the human(ish) process of adopting something not fully understood as fact because "the math works".

Basic doppler shifting is easy to observe and validate (I think train whistle, but perhaps that's not a good model). Cosmological shifting does not appear to be quite so easy to validate .

I wonder if there are alternative theories to what is being observed. Tired light sounds like it has had its moment in the sun. Anything else?

 

[Helio]

Thanks. The concept is challenging to me.

There are also a number of Youtube videos on it, but also Space.com has done some nice articles.

Here is one article.

The methodology used to determine/validate the Hubble Constant is itself seemingly variable and, seemingly, under debate. Using something variable/debatable as a constant is where I lose it. I struggle with the human(ish) process of adopting something not fully understood as fact because "the math works".

I think it really helps to learn science by learning the history on how an idea developed over time. The BBT is a great example of this.

1) Einstein introduces GR (General Relativity), uniting gravity with SR (Special Relativity). Both are mental mind-benders.

2) Prior to this, an astronomer with a really cool name (Vesto Slipher) left the farm to be an astronomer. The wealthy businessman, P. Lowell, gets excited that there may be evidence of life on Mars, though he likely misunderstood that the Italian astronomer who thought he could observe canali on Mars, really meant water systems (rivers) not man-made canal systems. He builds his Flagstaff observatory and hires Slipher.

Lowell had Slipher use a spectrograph on nebulae -- they assumed there were no other island universes (galaxies) in those days.

Slipher had to lean into the telescope for hours on very cold nights to get enough photons to record a spectrograph, was able to get perhaps a dozen, IIRC, redshifts and a couple of blueshifts.

Doppler was expected for anything moving in space. So those redshifts proved that galaxies were receding from us, right? Nope, it didn't happen.

2) At about the same time, going on memory, Einstein, and his friend deSitter, tried to apply GR to the cosmos since GR could address both spacetime and gravity, ubiquitous in space.

3) Interestingly, Einstein was not able to get a cosmos that could explain redshift since he was only accepting a static universe. DeSitter, on the other hand, calculated a static cosmos that did explain redshift. But deSitter had one quirk in his model -- he had no mass in the universe to allow redshift, apparently. [I believe that the highly respected deSitter, and his friendship with Hubble, and others, left an impression that redshift might not be a Doppler effect. Hence Hubble, contrary to many articles and books, never once argued that the universe is expanding.]

4) Also about this time, there was a new graduate from MIT, who was also a Belgium priest (Georges Lemaitre). He got to meet our friend Slipher. He likely gained respect for his redshift work.

So, using his GR prowess and respecting the importance of Doppler redshift, he saw that an expanding model would solve the dilemma between Einstein and deSitter. Einstein did see this work and said the math was good but the physics (reality of it) was an "abomination". [He later praised Lemaitre.]

Hubble greatly improves on the list of redshift objects (galaxies) and also was able -- with the world's largest telescope (100" at Wilson) -- to discover a Cepheid Variable in the Andromeda Nebula, which produced the first serious result for galactic distances. Distance and redshift results (whatever they represented) had a linear relationship. [This data came after Lemaitre first published.]

So finally, we have come to the one point that I think is helpful in understanding the foundation of BB -- reversing the clock.

Lemaitre, from his model and redshift data, realized that the universe is expanding as time progresses. So what happens if we reverse the clock? Contraction, contraction, and more contraction. Eventually you squeeze all the universe: spacetime, energy, matter, whatever into something super dense and tiny. He called it the primeval atom.

So, the theory never began as something small but something we see every day (expansion). Does that help?

Surprisingly, the state of physics is such that all that squishing of the universe can be modeled mathematically even down to the first trillionth of a trillionth of a trillionth of a second, and a little more. The math models any closer to t=0 seconds have "all the wheels fly-off" with wild and erroneous infinity results. So, BBT doesn't, and is incapable of, addressing where the universe came from. Philosophy and metaphysics, at this point, takes over from true science.

Basic doppler shifting is easy to observe and validate (I think train whistle, but perhaps that's not a good model). Cosmological shifting does not appear to be quite so easy to validate .

I'm pretty sure it all started-out with a Doppler model, but, today, this has advanced to a "cosmological redshift" - where spacetime somehow stretches those wavelengths over time and distance. For one reason the Doppler model fails, we are able to see the most distant regions traveling faster than light (this would be another thread topic), and Doppler math fails to allow such a circumstance.

I wonder if there are alternative theories to what is being observed. Tired light sounds like it has had its moment in the sun.

The main contester to the BBT, was the Steady State theory. But cosmology has developed considerably such that the evidence overwhelming supports BBT, and a tenet of the SST (hydrogen generation) is no longer plausible.

Anything else?

Well, now that I've gone this far. I will list all the arguments that I know regarding BBT in the next post (for future reference).

My compliments to all readers who have endured this... Pome (Post-tome)!

 

[Helio]

Scientific evidence supporting BBT (Big Bang Theory). [From something I did in 2003, so an update would be welcome.]

BIG BANG BULLETS:

....>The Expansion of the Universe.
....> Hubble Constant (redshift)
....> Einstein's field equations (1916) predicted an expanding (or contracting) universe
....> Time Dilation of Supernova
....> Gamma Ray Bursts
....> The CMBR - Cosmic Microwave Background Radiation.
........> The wavelength (microwave)
........> The Temperature (2.73K).
........> The Blackbody Results.
........> The "smoothness" (isotropy) [Inflation required]
........> The very small "roughness" (anisotropy) in this radiation.
........> The angular size of the "hot" spots matching predictions.
........> The power spectrum
....> Distant Cloud temperatures
....> The Element Abundances from Nucleosynthesis.
....> Helium (25%)
....> Deuterium, its relative abundance.
....> The observed Differences in Galaxies between today's and earlier ones.
........> Paucity of distant Barred Spirals.
........> Less organized distant Spirals.
........> No local Quasars.
....> The Age of the Universe in relation to Stellar Compositions.
....> Olber's Paradox resolved.
....> Entropy - "The universe is dying" (Helmholtz & 2nd Law).
....> Galactic Superstructure of Super Clusters and Galactic Strands
....> No Ancient Objects older than 15 billion years.
....> The anisotropy found in background neutrino mapping, probably.
....> The Lyman Forest morphology

 

[sam85geo]

Many thanks folks for the directions, hints and references. I plan to utilize the current restrictions and lock-downs to uninterruptedly "crunch" through what's been provided as best I can. The expansion of space is an exhilarating topic with startling implications.

 

[vincenzosassone]

No Ancient Objects older than 15 billion years.

Now I don't want to say anything of bad that goes against the BBT, is more a question instead!
Why we can extimate the age of the Universe, so from the beginning of the expanction to now, to be 13,77+-0.04 billion years old? Maybe in the not observable Universe there are many objects older than 15 billion years, why our scientists are so sure about?

 

[Helio]

Now I don't want to say anything of bad that goes against the BBT, is more a question instead!
Why we can extimate the age of the Universe, so from the beginning of the expanction to now, to be 13,77+-0.04 billion years old? Maybe in the not observable Universe there are many objects older than 15 billion years, why our scientists are so sure about?

The strongest evidence for the BBT is found in the CMBR (as mentioned in the list).

The age of the CMBR is probably that 13.8 or 13.77 Billion years -- the exact date will be all but impossible to pin down tightly, so every date will have a margin of error.

This time frame goes back to the date for the CMBR. We know its redshift and we know, fairly closely, what the original wavelengths were in that near perfect blackbody emission profile.

Since the CMBR is the point in time when atoms first formed, it's clear there would be no stars to have had time to form.

I use 15 billion years for wiggle room in case the expansion rate is less linear than originally expected due to DM and DE affects on the expansion rate. I'm no expert at this.

Recall that the prior theories were based on a more infinite-aged universe, so a mere 15 billion years is very restrictive for those theories, which now look more and more erroneous.

 

[vincenzosassone]

CMBR

Alright, Cosmic Microwave Background is important as evidence. I also know a lot about them, but I didn't know actually that they are of the greatest importance in this field ( or better, I thought them to be important, but not so important).

Recall that the prior theories were based on a more infinite-aged universe, so a mere 15 billion years is very restrictive for those theories, which now look more and more erroneous.

One hundred percent! Our Universe is older for me.

The age of the CMBR is probably that 13.8 or 13.77 Billion years

Only one last thing, we are talking about something of not very sure, aren't we? Anyway I don't want to blame you, I want to say that many time our people try to guess and then we have somethign of instable.
Many thanks for the information!

 

[Helio]

The significance of the CMBR to cosmology probably can't be overstated.

This is another example where the history behind the BBT makes it more important and interesting.

Lemaitre rewound the clock for the universe we see today so that the contraction would bring it down to that of a large atom, or something close. Since it is a true theory and testable, as his GR model became acceptable as a legitimate theory, more and more physicists began giving it scrutiny, which means they would look for ways to test it.

All of the items listed in the above post are tests for the theory. The existence of a CMBR, however, was not recognized until years later. The physics of an expanding glob of energy ("pure energy" per Spock ) as it cooled due to expansion would necessarily form quarks, then protons and electrons, etc.. But it had to expand to a specific point when the temperatures and densities (per the laws) would suddenly allow electrons to combine with the protons to form the very first atoms. 9 out of 10 would be hydrogen, helium would be the rest, with very few exceptions (e.g lithium).

Based on current models, the time frame would have required about 380,000 years before the temperature, density, etc., would be such where the temp. would reach around 3000K for the electrons to be able to be bound to the protons.

Moments prior to this event, the sea of electrons (none were bound) caused all those zillions of photons to scatter all over the place as they encountered those electrons and protons. Visibility distance would be measured in perhaps millimeters, if an eyeball happened to be there.

But, the moment the electrons combined to convert all those free electrons into bound ones, was the moment light was no longer scattered in all different directions, for the most part, at least.

Thus, physicists had something very predictable and some of the tests have been for that burst of unobstructed light, namely:

1) This light would look like a blackbody distribution. (A plot of energy per unit wavelength matching a 3000k spectrum.)

2) The cosmological redshift would require that 3000K spectrum to have shifted into the microwave band so that, though still a BB profile, would be seen as one for a 2K to 4K temp. bb.

[Princeton realized this and was building a microwave detector to see if they could be the ones to confirm this BB prediction. But, Bell Labs folks found it first, accidentally.]

3) That background light would also be very isotropic and homogeneous. There would be incredible uniformity throughout.

But not perfect uniformity since it is clear that we have stars and galaxies. Thus there would have been a lot of tiny variation in temperatures, density, etc. This is called the anisotropy.

4) The slight anisotropy would reveal itself as regional and would form a measurable pattern where the sizes observed would reveal a lot about it.

5) There would be a power spectrum to this energy distribution, which gets a little more complicated.

There is probably more, but the important point is that the CMBR should not exist for any static model. Only the BBT would make sense if this CMBR was ever found.

It was a necessary prediction of BBT, and when it was discovered, Hawking apparently stated that it was the "nail in the coffin" for the Steady State theory, or any static theory.

I recall seeing some scientists say it is the greatest discovery of the 20th century, some rate it even higher.

 

[vincenzosassone]

I only want to say that I'm stuck for words, you know very well the theory of the Big Bang! And I would want to continue talking about this very detailed proof, but I only want to say one thing: perhaps in the last post I wrote badly my idea, but I want to say that is very hard to detect the age of our Universe because we have data not so certain... There is all there is to say, I believe in the BBT but I think that many events and many details were lost.

The slight anisotropy would reveal itself as regional and would form a measurable pattern where the sizes observed would reveal a lot about it.

I hate to write something I'm not sure, for this reason I'll make my statement a question, was anisotropy caused by the inflation? I remember this even as the cause of asimmetry of the Universe an for this reason I wanted to know more.
Many thanks!

 

[Helio]

I only want to say that I'm stuck for words, you know very well the theory of the Big Bang! And I would want to continue talking about this very detailed proof, but I only want to say one thing: perhaps in the last post I wrote badly my idea, but I want to say that is very hard to detect the age of our Universe because we have data not so certain... There is all there is to say, I believe in the BBT but I think that many events and many details were lost.

A theory that addresses all the cosmos will always be a work in progress. It, like all theories, can’t be proved, unlike in math, so the question of the degree mainstream science gives it is based on the quality of the observations and the number of lines of evidence supporting. The list given above represents many different lines of evidence — multiple arrows pointing to a single point. Another theory or new version of this one are possible, but any alternative must produce at least answers for all those different areas of observations.

I hate to write something I'm not sure, for this reason I'll make my statement a question, was anisotropy caused by the inflation?

This question goes to your last statement. Quantum physicists were necessary to look at those first nanoseconds. The quantum world is a lot of things, but smooth and homogeneous it’s not. So the degree of anisotropy should be much greater than observed. Alan Guth introduced Inflation theory that argued for a hyper expansion rate that only lasted for much less than a nanosecond, but it had a great smoothing effect, lowering the anisotropy. Many other versions of this have followed as well.

Inflation theory, given the above, doesn’t have all those other lines of evidence, hence it’s much easier to question. Every scientific theory must must make testable predictions, which are few with what might explain the tiny early anisotropy — probably another near-perfect circumstance to make our wonderful universe.

 

[vincenzosassone]

A theory that addresses all the cosmos will always be a work in progress.

Of course, we'll never know exactly, this is something of bad!

This question goes to your last statement. Quantum physicists were necessary to look at those first nanoseconds. The quantum world is a lot of things, but smooth and homogeneous it’s not.

If I know something about the Universe is that nothing is smooth or regular. There are always some imperfections also in the most "perfect" things. Anyways, before I forget to tell it, I want to say that I talked about anisotropy matching it with inflation because is the most logical possibility. I'm studying astronomy and cosmology as self-taught and many times I use my insight and logic to bring problems to a solution. For this reason I put it at stake, I didn't know that this wasn't well analized!

Inflation theory, given the above, doesn’t have all those other lines of evidence

I understand, it cannot. Given that it is connected too much with BBT, the proof are lacking...
I hope I understand fully your speech and I don't bore you! thanks!