Author Topic: Cosmic Supervoids  (Read 238 times)

Cosmic Supervoids
« on: August 13, 2019, 04:56:37 PM »
I'm wondering what the exceptionally weak gravitational fields at the centers of the cosmic voids does to time. I've read that time in the voids "moves" or "flows" faster than time in the galaxy clusters, and that in those locations the universe is actually older than it is where the gravitational fields are stronger. This might mean that space is expanding faster in the voids, causing the voids to grow larger, which may drive universal expansion. There is a gravitational gradient, and therefore a temporal gradient, between the more and less dense regions, causing the less dense regions to expand faster than the denser regions. This may have something to do with why they're having such a hard time pinning down the Hubble parameter. It might be that the Hubble parameter is not a constant, but varies with location with respect to voids and clusters.

Here is some background on the voids:


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Here is a map of the nearest voids and galaxy clusters:


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Apparently, the voids get bigger, and I would expect the growth rate to increase as the voids grow. The largest voids would grow more quickly than smaller ones.



Of course, this is all just speculation, but it's fun to think about. Does the universal expansion cause the voids to grow larger, or do the growing voids cause the universal expansion?
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"The Christian resolution to find the world ugly and bad has made the world ugly and bad.”
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Re: Cosmic Supervoids
« Reply #1 on: August 13, 2019, 09:01:32 PM »
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It might be that the Hubble parameter is not a constant, but varies with location...

Possibly, but two teams working independently in the late 90's confirmed that the Hubble Constant is not constant over time. They measured the received power of type 1a supernovae (which explode at a known power) to measure vast distances more accurately than possible before. To their surprise, they determined that the rate of acceleration is increasing. Particle physicists think it may be vacuum energy -- the more space, the more vacuum energy, which explains the acceleration.
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Offline Baruch

Re: Cosmic Supervoids
« Reply #2 on: August 14, 2019, 12:14:23 AM »
Observational cosmology over a billion years of observation to get the empirical data ... is HARD science.
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luu shalmaata luu balt’aata
May you be well, may you be healthy

Re: Cosmic Supervoids
« Reply #3 on: August 14, 2019, 04:13:18 PM »


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Possibly, but two teams working independently in the late 90's confirmed that the Hubble Constant is not constant over time. They measured the received power of type 1a supernovae (which explode at a known power) to measure vast distances more accurately than possible before. To their surprise, they determined that the rate of acceleration is increasing. Particle physicists think it may be vacuum energy -- the more space, the more vacuum energy, which explains the acceleration.

No one's quite sure just what is causing the accelerated expansion. They call it "dark energy" because they don't know what else to call it. But they don't really understand the mechanism of what's driving it.
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"The Christian resolution to find the world ugly and bad has made the world ugly and bad.”
Friedrich Nietzsche

Re: Cosmic Supervoids
« Reply #4 on: August 14, 2019, 04:30:49 PM »
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No one's quite sure just what is causing the accelerated expansion. They call it "dark energy" because they don't know what else to call it. But they don't really understand the mechanism of what's driving it.

You're right. The main culprit is Einstein's field equations. Now in any differential equation, when you integrate you end up with an arbitrary constant if the boundary conditions are unknown. And so that's what you get with the Einstein field equations, an arbitrary constant. It's energy density because those equations are about energy density. Other than that, those equations give no clue as to what is that energy, how it functions, what are the limits or any other features that would help us to understand. So it's dark, as in obscure...;-)
β€œReligion was invented when the first con man met the first fool.” - Mark Twain

Re: Cosmic Supervoids
« Reply #5 on: August 14, 2019, 04:38:39 PM »
It seems to me that as the voids grow larger, their growth-rate would increase as well, which could explain the accelerated expansion. The difference in time flow between the clusters and voids may be miniscule, but over the lifetime of the universe could have added up to a significant amount of elapsed time difference since the big bang.
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"The Christian resolution to find the world ugly and bad has made the world ugly and bad.”
Friedrich Nietzsche

Re: Cosmic Supervoids
« Reply #6 on: August 14, 2019, 05:31:34 PM »
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It seems to me that as the voids grow larger, their growth-rate would increase as well, which could explain the accelerated expansion. The difference in time flow between the clusters and voids may be miniscule, but over the lifetime of the universe could have added up to a significant amount of elapsed time difference since the big bang.

Here's a good writeup on the accelerating expansion and why many particle physicists think it's vacuum energy. The problem is we don't have a good measurement of vacuum energy. Right now QFT doesn't make a prediction for vacuum energy density, and attempts to estimate it extrapolating from QFT result in an estimate 120 orders of magnitude greater than what observations in astrophysics suggest.

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Gentlemen, you can't fight in here! This is the War Room! -- President Merkin Muffley

My mom was a religious fundamentalist. Plus, she didn't have a mouth. It's an unusual combination. -- Bender Bending Rodriguez

Offline Baruch

Re: Cosmic Supervoids
« Reply #7 on: August 14, 2019, 07:27:30 PM »
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Here's a good writeup on the accelerating expansion and why many particle physicists think it's vacuum energy. The problem is we don't have a good measurement of vacuum energy. Right now QFT doesn't make a prediction for vacuum energy density, and attempts to estimate it extrapolating from QFT result in an estimate 120 orders of magnitude greater than what observations in astrophysics suggest.

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Yes.  I have read Dr Baez too.  Without a good quantum gravity theory, we know nothing about this vacuum shit.  Theoretical physicists will continue to speculate (I prefer Carlo Ravelli), and experimental physics will remain frustrated.

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If we don't know what time is, then we really don't know much at all.
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luu shalmaata luu balt’aata
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Re: Cosmic Supervoids
« Reply #8 on: August 16, 2019, 08:22:17 AM »
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Without a good quantum gravity theory, we know nothing about this vacuum shit. 

Quantum gravity theory is over-rated...
β€œReligion was invented when the first con man met the first fool.” - Mark Twain

Offline Baruch

Re: Cosmic Supervoids
« Reply #9 on: August 16, 2019, 05:22:15 PM »
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Quantum gravity theory is over-rated...

Pythagorean panaceas usually are.  Pythagoras already had the answer ... "one".
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luu shalmaata luu balt’aata
May you be well, may you be healthy

Re: Cosmic Supervoids
« Reply #10 on: August 16, 2019, 05:25:12 PM »
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Pythagorean panaceas usually are.  Pythagoras already had the answer ... "one".
Well, TOE is an interesting fantasy. But some people are rude when you debunk...
β€œReligion was invented when the first con man met the first fool.” - Mark Twain

Offline Baruch

Re: Cosmic Supervoids
« Reply #11 on: August 16, 2019, 05:53:51 PM »
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Well, TOE is an interesting fantasy. But some people are rude when you debunk...

If the first guy got the right answer, then what point do the successors have?
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luu shalmaata luu balt’aata
May you be well, may you be healthy

Re: Cosmic Supervoids
« Reply #12 on: August 16, 2019, 06:13:09 PM »
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If the first guy got the right answer, then what point do the successors have?

A prime number?
β€œReligion was invented when the first con man met the first fool.” - Mark Twain

Offline Baruch

Re: Cosmic Supervoids
« Reply #13 on: August 16, 2019, 08:07:33 PM »
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A prime number?

What is more prime than "one"?  Pythagoras knew "two" and "three" also.
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luu shalmaata luu balt’aata
May you be well, may you be healthy

Re: Cosmic Supervoids
« Reply #14 on: August 16, 2019, 08:09:49 PM »
One isn't a prime number, though it is the loneliest number.
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"The Christian resolution to find the world ugly and bad has made the world ugly and bad.”
Friedrich Nietzsche

 

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