Cosmological Stuff

Palomar · 2004-05-11 08:15:42

*I'm reading an article in the May 2004 issue of _Scientific American_ entitled "The Myth of the Beginning of Time," written by Gabriele Veneziano ("father of the String Theory").

He mentions that cosmic expansion has gone through periods of acceleration and deceleration. I'm not sure I've read before that the expansion has ever DEcelerated. :-\ I thought it was a continual acceleration process (based on what I'd read before).

How could the cosmos DEcelerate expansion-wise? [:EDIT:] And if it decelerates...HOW does it accelerate again?

Also, does this (deceleration) tie in with the theory (?) that light speed may VARY, i.e. actually slow down as well? I don't have a link to a related article, but I've read before that, in the lab, scientists have slowed down light speed (or so they claim). But in nature, however, CAN light speed slow -- naturally? And again, does light-speed variability (?)have anything to do cosmic expansion deceleration (and acceleration)?

And another question: Why does everything SPIN? Planets, moons, galaxies, black holes...just about everything spins. Is this a result of the tremendous continuing momentum of force from the Big Bang...or from gravity...or a combination of the two?

--Cindy

Byron · 2004-05-11 10:36:55

Yeah, I've been reading that article as well...interesting, to say the least. I've also seen a "NOVA" episode a few months back concerning string theory, which did an excellent job of putting this cutting-edge theory into layman's terms.

As for the acceleration/deceleration issue goes, it's the properties of the "strings" themselves that essentially prevent the universe from collasping into a singlelarity, instead it "rebounds" outward in a burst of quantum energy. But I've always assumed in the past that it was the force of gravity that would cause the eventual deceleration of the universe, at least until they discovered that the universe is actually expanding at an accelerating pace as time moves forward, which posulates there's a stronger force than gravity (inflation) at work here.

I particularily like the "brane" idea...in that there's all kinds of parallel universes co-existing with this one, and when two of these "branes" collide...presto! A whole new universe is born. Anyhow, it's nice to think that the universe may very well have been here forever, and always will be, which is pretty much what I've always believed. (I just can't get over the idea that the whole universe began with a priordial "seed" at the dawn of the Big Bang...I'm like, where did that come from, then??..lol)

As for why everything spins, my take on that it's gravity's doing...as matter comes together in things like stars and planets, angular momentum is converted to a spinning motion as it comes in contact with each other. (as the closer the "center" of gravity is, the stronger and faster the pull...much like how a skater speeds up when she pulls her arms and legs in.)

I hope this helps ya at least a little...lol...I have a hard time understanding this in my mind, let alone trying to explain it in words...lol.

B

flashgordon · 2004-05-11 14:03:16

well, I remember way back in like 98, that there were supernova observations that suggested that the universe has some sort of dark energy that accellerated the expansion of the universe a few billion years ago(i'm wondering if this has anything to do with the soapbubble structure of the current universe, where all the galaxies are dotted on bubbles).

There are some thieoretical ideas that could make for dark matter such as supersymmetry that is required for string theory, but dark energy has been a total surprise; in other words, nature has totally thrown us a curveball, and we haven't a clue!

Euler · 2004-05-11 14:43:42

Also, does this (deceleration) tie in with the theory (?) that light speed may VARY, i.e. actually slow down as well? I don't have a link to a related article, but I've read before that, in the lab, scientists have slowed down light speed (or so they claim). But in nature, however, CAN light speed slow -- naturally? And again, does light-speed variability (?)have anything to do cosmic expansion deceleration (and acceleration)?

My understanding of VSL (variable speed of light) theory is that the rate of expansion of the universe is one of the factors that determine what the speed of light is. The idea is that if the universe starts expanding too fast, the speed of light and other constants will change in a way that will slow down the universe. Conversely, when the universe starts expanding too slowly the constants will change in the opposite direction and speed the universe back up.

The slowing of light in a lab is different. VSL and classical relativity disagree on whether speed of light in a vacuum can change, but both agree that light can slow down when it is not in a vacuum. In fact, this phenomenon is the reason why light bends in a lens. Light travels at about 3/4 c in water and around 2/3 c in glass. What is different about the scientists are doing in the lab is the amount that they have slowed light- I think that they have it down to just a few meters per second.

Mark Friedenbach · 2004-05-11 15:13:35

How could the cosmos DEcelerate expansion-wise?

Well, by deceleration he means the the rate at which the universe is expanding is slowing down, not that it is shrinking. It's actually the reverse that is surprising -- that the expansion of the universe might be speeding up. One would expect gravity to slow it down.

Palomar · 2004-05-12 06:31:40

*Thanks for the replies, everyone.

Byron wrote: "(I just can't get over the idea that the whole universe began with a priordial "seed" at the dawn of the Big Bang...I'm like, where did that come from, then??..lol)"

*Yes, I agree. I mentioned the same article and some comments on singularity in the "Singularity" thread. I really doubt this universe is the first or will be the last. But then we're back eventually to what WAS -the- beginning? My aching brain...

Euler wrote: " The idea is that if the universe starts expanding too fast, the speed of light and other constants will change in a way that will slow down the universe. Conversely, when the universe starts expanding too slowly the constants will change in the opposite direction and speed the universe back up."

*Wow. An analogy to that almost comes to mind... :-\ I might have to jot in an "edit" later, if I recall it [oh -- just recalled...the self-regulating cycle of nuclear reactions in the Sun]. Okay, from what I understand (ha ha) of the Theory of Relativity, Time is dependent upon Light Speed?

--Cindy

SBird · 2004-05-12 10:36:03

I've been reading the SciAm article as well and it's a good review of some of the alternate Big Bang theories out there. However, those alternate theories rely upon string theory. String theory still has absolutely NO experimental evidence to back it up. Although it's presently the most promising physics theory out there right now, it's by no means a done deal. Until then, these articles are basically nothing but idle speculation, at least until we can start getting some much higher quality pitures of the cosmic background radiation.

Palomar · 2004-05-13 20:45:13

*More speculation...

Okay, am still reading the article (I've been *very* busy off-line as well, and all of my reading has slowed...).

On page 56 he's discussing the properties of our Milky Way Galaxy as being basically the same as distant galaxies (hundreds of millions of light-years away). He discusses "intercommunication" (pertaining to this homogeneity) in the early universe and uses the analogy of 12 people showing up at a party all dressed alike suggesting attire having been coordinated in advance, versus the coincidence of 2 people showing up dressed alike. This I understand (just typed it out for a bit of background info for folks who might not have the magazine).

He goes on to the next paragraph in which he says, "Before this phase, galaxies or their precursors were so closely packed that they could easily coordinate their properties. During inflation (of the universe of course), they (galaxies) fell out of contact because light was unable to keep pace with the frenetic expansion."

Okay, I understand this is all speculation. But I'm curious: What did the expansion consist of, to outpace *light*? Gravity? Dark matter? And also, I read in (IIRC) _Introducing Stephen Hawking_ that supposedly nothing can travel faster than (or "outpace") light speed because whatever is traveling to near that speed ends up stopping because all the matter/mass (??) in the entire universe would bunch up in front of the object, thereby stopping it. So, of course, I'm wondering how anything could outpace light and what that would be.

::sigh::

--Cindy

::EDIT:: He also discusses ascribing the "inflationary spurt" to potential energy stored in "a new quantum field, the inflaton [magazine's typo of "inflation"?]," and gives the figure of 10 to the -35 power "second after the big bang."

Ten to the minus thirty-fifth power. Could someone please convert that to a *decimal figure* for me? I honestly don't know how to do that...and I wouldn't ask if I could. :-\ Would be appreciated.

Mark Friedenbach · 2004-05-13 22:46:15

Okay, I understand this is all speculation. But I'm curious: What did the expansion consist of, to outpace *light*? Gravity? Dark matter? And also, I read in (IIRC) _Introducing Stephen Hawking_ that supposedly nothing can travel faster than (or "outpace") light speed because whatever is traveling to near that speed ends up stopping because all the matter/mass (??) in the entire universe would bunch up in front of the object, thereby stopping it. So, of course, I'm wondering how anything could outpace light and what that would be.
::sigh::

Nothing is actually moving, but the distance between two "stationary" objects is increasing.

::EDIT:: He also discusses ascribing the "inflationary spurt" to potential energy stored in "a new quantum field, the inflaton [magazine's typo of "inflation"?]," and gives the figure of 10 to the -35 power "second after the big bang."
Ten to the minus thirty-fifth power. Could someone please convert that to a *decimal figure* for me? I honestly don't know how to do that...and I wouldn't ask if I could. :-\ Would be appreciated.

A decimal point followed by thirty-four zeros and then a 1.

Palomar · 2004-05-14 11:53:06

Okay, I understand this is all speculation. But I'm curious: What did the expansion consist of, to outpace *light*? Gravity? Dark matter? And also, I read in (IIRC) _Introducing Stephen Hawking_ that supposedly nothing can travel faster than (or "outpace") light speed because whatever is traveling to near that speed ends up stopping because all the matter/mass (??) in the entire universe would bunch up in front of the object, thereby stopping it. So, of course, I'm wondering how anything could outpace light and what that would be.
::sigh::
Nothing is actually moving, but the distance between two "stationary" objects is increasing.

*Erm...that sounds like a contradiction (not seeking to besmirch you in any manner, please understand; I have no doubt "it's me" -laugh-). If -nothing's- moving, how can there be increased distance?

Two toy boats on a lake float apart...*they* are not moving, but the water must be. They couldn't have increased distance between them without something pulling (moving) them apart. :-\

Thanks for answering the other question.

Will keep "chipping away" at figuring this stuff out (slowly but surely!).

--Cindy

SBird · 2004-05-15 01:03:25

Yeah, it's a bit confusing and even though I understand the reasoning, I'm still not comfortable with the concept. Basically, we're floating in spacetime which is growing bigger. Two stationary objects will move further apart since more space has appeared between them. Spacetime is allowed to do that sort of stuff at arbitrary speed.

10 to the minus 35 is basically 1 divided by 10 to the 35. So 4.5*10^-34 = 1/4.5*10^34.

Euler · 2004-05-15 01:23:13

10 to the minus 35 is basically 1 divided by 10 to the 35. So 4.5*10^-34 = 1/4.5*10^34.

No, 4.5*10^-34=4.5*1/(10^34)

Gennaro · 2004-05-15 09:21:36

Well, by deceleration he means the rate at which the universe is expanding is slowing down, not that it is shrinking. It's actually the reverse that is surprising -- that the expansion of the universe might be speeding up. One would expect gravity to slow it down.

For a lay person this doesn't seem to make sense. How can the expansion speed up, let alone fluctuate when the speed of light is constant and nothing is supposed to move faster than the speed of light?
If relativity is true, logically, the only way the universe could have expanded would have been by the speed of light (in vacuum), neither slower nor faster as long as there is some sort of lightsource somewhere, emitting light.

Mark Friedenbach · 2004-05-15 12:33:31

The expansion of the universe isn't caused by objects moving away from each other--it's the space between all objects literally increasing. It's like stretching a rubber band, if you mark two points on the rubber band and then stretch it, they "move away from each other" only in the sense that the distance between them increases, but from their point of view they never actually accelerated. The distant edge of the universe is not flying away from us a huge speed, it's actually more or less stationary and it's spacetime itself that is expanding, much like the stretching of the rubber band.

Gennaro · 2004-05-15 15:50:35

Good reply!

But then the next lay person's question shows up.
This with space-time rubberbands expanding while galaxies never having accelerated, isn't that just another way of saying that what is moving away from something else according to relativity, is totally arbitrary without an objective frame ("ether") in which bodies move?

In such a case it's irrelevant whether space is expanding or light is travelling, and thus both (since they are the same phenomenon) must follow the same fundamental laws of nature which says that nothing may move ("expand") faster than the speed of light.

Or is there some sort of fundamental difference between space expansion (space increasing in itself, not edges flying away) and every other form of expansion?

SBird · 2004-05-16 23:43:11

10 to the minus 35 is basically 1 divided by 10 to the 35. So 4.5*10^-34 = 1/4.5*10^34.
No, 4.5*10^-34=4.5*1/(10^34)

My bad, you're right, I shouldn't post math when I'm tired.

Palomar · 2004-05-18 17:17:39

http://story.news.yahoo.com/news?tmpl=s … 18201615]A lonely place?

*One of the better Yahoo! science articles I've seen. Deals with expansion of the universe and dark energy. Universe really *is* accelerating, they say. Use of Chandra X-Ray Observatory.

"'Dark energy is pushing the universe apart and accelerating its expansion,' Allen said, noting research that used Einstein's model of the constant density of dark energy."

Discusses three scenarios re: density of dark energy.

Dark energy -and- dark matter...hmmmm. Comments?

--Cindy

::EDIT:: "Researchers who led the study estimate that the universe is composed of 75 percent dark energy, 21 percent dark matter, and only four percent of normal matter such as that making up the Earth."

Wow...I did not know that.

Also: "...its acceleration due to the effect of being repulsed by dark energy."

Palomar · 2004-05-18 20:08:30

http://story.news.yahoo.com/news?tmpl=s … 18201615]A lonely place?
*One of the better Yahoo! science articles I've seen. Deals with expansion of the universe and dark energy. Universe really *is* accelerating, they say. Use of Chandra X-Ray Observatory.
"'Dark energy is pushing the universe apart and accelerating its expansion,' Allen said, noting research that used Einstein's model of the constant density of dark energy."
Discusses three scenarios re: density of dark energy.
Dark energy -and- dark matter...hmmmm. Comments?
--Cindy
::EDIT:: "Researchers who led the study estimate that the universe is composed of 75 percent dark energy, 21 percent dark matter, and only four percent of normal matter such as that making up the Earth."
Wow...I did not know that.
Also: "...its acceleration due to the effect of being repulsed by dark energy."

*(Continuing from above): Is "potential energy" synonymous with or similar to "dark energy"? Dr. Veneziano's article mentions "potential energy" repulses gravity.

Also, what the heck is "inflaton"? I thought at first it was a typo in the magazine article. Nope; it's used more than once (unless it's a repeated error in the text, but the word "inflation" is also used). I presume it's related to inflation, given the way it's used in context, but I dislike presumptions. I checked Wikipedia for "inflaton" -- nothing. Searching on Google
http://nedwww.ipac.caltech.edu/level5/W … l]produces these sorts of results. :-\ Super-technical stuff.

I've seen a paper from Chinese scientists, translated, entitled "Primordial Black Hole Formation from Inflaton." http://www.worldscinet.com/ijmpd/09/090 … html]Click Unfortunately, you must purchase to read it.

I checked Webster's Online for a definition of "inflaton":
http://dictionary.reference.com/search?q=inflaton]The result. :-\

Any feedback on my questions would be very much appreciated.

--Cindy

::EDIT:: Okay...now he's saying "THE inflaton," as in exactly what "THE inflaton" was and what gave it "a huge initial potential energy"...so I take it an "inflaton" is what inflates/causes inflation or is the source of the inflation. Am I right? (If so, I find it still weird that the word "inflaton" is absent from Webster's).

Palomar · 2004-05-19 21:39:04

*I believe I found the answer to what an "inflaton" is: Potential energy stored in a new quantum field (based on my reading in the article).

--Cindy

Mars_B4_Moon · 2022-09-02 06:49:32

I might update this old thread with topics like unexplained mysterious phenomenon

Mysterious rings in new James Webb Space Telescope image puzzle astronomers
https://www.space.com/james-webb-space- … ples-image
Concentric ripples surrounding a distant star have a strange, squarish shape.

Mars_B4_Moon · 2022-09-12 07:34:58

Another article

Ringed Star from James Webb Telescope Baffles Scientists
https://nerdbot.com/2022/09/06/ringed-s … cientists/
This most recent discovery has scientists enthused and confused. The telescope sent back an image in July. A star known as WR 140, a Wolf-Rayet star, is doing something bizarre.

Mars_B4_Moon · 2023-03-03 15:12:42

Galaxy Super Cluster Structures

'The giant arcs that may dwarf everything in the cosmos'

https://www.bbc.com/future/article/2023 … the-cosmos

Mars_B4_Moon · 2023-05-26 03:54:26

Chandra and JWST Join Forces in a Stunning Series of Images

https://www.universetoday.com/161551/ch … of-images/

New images that combine data from NASA’s Chandra X-ray Observatory and the James Webb Space Telescope (JWST) JWST have just been released! The images feature four iconic astronomical objects, showcasing the capabilities of these observatories by combining light in the visible, infrared, and X-ray wavelengths. These include the NGC 346 star cluster located in the Small Magellanic Cloud (SMC), the NGC 1672 spiral galaxy, the Eagle Nebula (Messier 16, or M16), and the spiral galaxy Messier 74 (aka. the Phantom Galaxy).

These objects were made famous by the venerable Hubble Space Telescope, which took pictures of them between 1995 and 2005. Since it commenced operations, the JWST has conducted follow-up observations that provided a sharper view of these objects that captured additional features. Hubble and the JWST even teamed up to provide a multi-wavelength view of the Phantom Galaxy last year. By adding Chandra’s famed X-ray imaging capabilities to Webb’s sensitivity and infrared light, these latest images provide a new glimpse of these objects, revealing both faint and more energetic and powerful features.

Mars_B4_Moon · 2023-09-07 12:59:22

If Earth were an exoplanet, JWST would know there's an intelligent civilization here
https://phys.org/news/2023-09-earth-exo … ation.html

How the world’s biggest particle accelerator is racing to cook up plasma from after the big bang
https://www.popsci.com/science/large-ha … on-plasma/

Eerie, ultra-detailed photo of a lightning 'sprite' exposes one of nature's least understood phenomena
https://www.livescience.com/planet-eart … -phenomena
An astronomer in Slovakia captured the rare luminous phenomenon as it briefly flashed in Earth's upper atmosphere during a thunderstorm.

It's going to take more than early dark energy to resolve the Hubble tension
https://phys.org/news/2023-09-early-dar … nsion.html

Mars_B4_Moon · 2023-11-02 09:41:39

odd looking but not unexplained

NASA X-ray Telescopes Reveal the “Bones” of a Ghostly Cosmic Hand
https://www.nasa.gov/missions/chandra/n … smic-hand/

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#1 2004-05-11 08:15:42

Re: Cosmological Stuff

#2 2004-05-11 10:36:55

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#3 2004-05-11 14:03:16

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#4 2004-05-11 14:43:42

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#5 2004-05-11 15:13:35

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#6 2004-05-12 06:31:40

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#7 2004-05-12 10:36:03

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#8 2004-05-13 20:45:13

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#9 2004-05-13 22:46:15

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#10 2004-05-14 11:53:06

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#11 2004-05-15 01:03:25

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#12 2004-05-15 01:23:13

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#13 2004-05-15 09:21:36

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#14 2004-05-15 12:33:31

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#15 2004-05-15 15:50:35

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#16 2004-05-16 23:43:11

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#17 2004-05-18 17:17:39

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#18 2004-05-18 20:08:30

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#19 2004-05-19 21:39:04

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#20 2022-09-02 06:49:32

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