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Post by kmsdrwho510 on Nov 4, 2012 18:30:36 GMT
I'm watching another series on Netflix about Space, the Universe and everything. Here's something that was not explained to my satisfaction:
We know when the Big Bang occured by looking at the current "remains" of the explosion and "winding the clock backward," but how did we do that? Those word in the quotes are what the show said, but they did not say how we are able to "wind the clock back" to determine the age of the Universe. Anyone know?
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Post by freegan on Nov 4, 2012 18:41:03 GMT
When they found out that space was expanding, they calculated the presumed age of the Universe on the assumption of the Big Bang (from zero space) model.
Then they found that the expansion of space is accelerating. (Not sure if they re-calculated.)
Anticipating a further question:
Space is postulated, in the current model, to have been created in the Big Bang (and continues to be created).
Even though matter that emitted light 13.5 billion years ago appears to us to be receding at speeds faster than light, it is an illusion.
They are not moving at that speed.
The space between us and the 'light horizon' is being created faster than light can travel across it.
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Post by kmsdrwho510 on Nov 4, 2012 21:05:16 GMT
That makes sense, thanks. I will post again, if the crazy program leads my wandering mind to more quetions.  |
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Post by kmsdrwho510 on Nov 4, 2012 21:06:47 GMT
The program is called How The Universe Works. It's narrated by Mike Rowe, which is why I started watching it. It's actually pretty good, but it assumes the viewer already understands some concepts they are talking about. While I have a huge interest in astronomy, there are a lot of things that still leave me scratching my head, going "huh?"
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Post by trakmec on Nov 6, 2012 6:08:39 GMT
Couldn’t you just go to the next birthday party and quietly count all the candles on the cake?  Actually it’s a great show with some very interesting comments. Something I’ve wondered about with regard to expansion is that we are using observable phenomena in the radiated spectrum. What if some of the original material has, for lack of a better term burned out? How would large masses, or greater distances affect our current understanding of the size of the universe and its speed of expansion. I realize that this is questioning something that by my own definition can’t be observed to be measure, but I do wonder what in theory this would mean. If in fact the leading edge of the expansion was cold and dark with much more matter in it the previously expected? suggestions? |
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Post by kmsdrwho510 on Nov 6, 2012 17:34:43 GMT
Couldn’t you just go to the next birthday party and quietly count all the candles on the cake? Only if they have red velvet with white frosting! ;D |
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Post by OziRiS on Nov 6, 2012 20:06:31 GMT
Couldn’t you just go to the next birthday party and quietly count all the candles on the cake? Actually it’s a great show with some very interesting comments. Something I’ve wondered about with regard to expansion is that we are using observable phenomena in the radiated spectrum. What if some of the original material has, for lack of a better term burned out? How would large masses, or greater distances affect our current understanding of the size of the universe and its speed of expansion. I realize that this is questioning something that by my own definition can’t be observed to be measure, but I do wonder what in theory this would mean. If in fact the leading edge of the expansion was cold and dark with much more matter in it the previously expected? suggestions? Nice twist! Like a lot of things in physics, the age we attribute the universe is theoretical at this point. If what you're suggesting turns out to be proven fact at some point, we might have to re-evaluate what we "know" about the time of creation completely. Good catch  |
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Post by Cybermortis on Nov 6, 2012 20:45:12 GMT
They are not looking at matter, but at the residual radiation released by the big bang that was, for lack of a better word, 'imprinted' onto the entire universe.
Because this radiation shifts frequency as it moves away from us - the Doppler-effect - and the way the frequency shifts at different speeds allows us to estimate the age of the universe.
We can do this by simply taking the speed of expansion, then calculating at which point all the radiation was in the same place. It would rather be like taking the speed of a car and using the time it has been travelling to calculate where it started from.
Matter we can't see falls under the heading 'dark matter', which basically just means matter that isn't emitting something we can detect. A black hole is a form of dark matter, as we can't observe the hole itself (we can only observe them when they are interacting with something else, usually a disk gas that is being compressed as it is drawn into the hole and emitting radiation due to the compression). Likewise planets are a form of dark matter, as we can't usually detect them directly. Rather we have to detect them through the effects they have on other stellar bodies and objects, such as stars.
We do know that there seems to be less matter in the universe that we expected. But this could be explained by 'dark matter', such as planets and black holes, that exist between galaxies.
Of course these calculations do require some assumptions, such as the speed of light having remained constant and that the universe is expanding at the same rate it always has - and I seem to recall that the latter may not be true, some observations seem to indicate that if anything the rate of expansion is increasing.
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Post by trakmec on Nov 7, 2012 0:22:27 GMT
Thanks Cyber,did not know the part about the "imprinted" radiation. As for the speed of light I have heard an interesting theory that says it may not have always been what it is now.
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Post by subductionzone on Nov 7, 2012 14:02:01 GMT
Thanks Cyber,did not know the part about the "imprinted" radiation. As for the speed of light I have heard an interesting theory that says it may not have always been what it is now. There are problems with changing the speed of light. The amount of energy in the universe is directly tied to the speed of light for example. If you double the speed of light you must also somehow quadruple the energy of the universe. Nuclear reactions would release a different amount of energy etc. I am betting that you do not have a theory, but a WAG. Usually in forums that are science oriented it is proper to use the scientific definition of the word "theory". |
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Post by trakmec on Nov 8, 2012 3:49:54 GMT
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Post by subductionzone on Nov 8, 2012 4:27:49 GMT
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Post by silverdragon on Nov 9, 2012 9:10:35 GMT
Stomp on the universe creation.....
I was watching something by Prof Steven Hawkins.
It lead to a discussion elsewhere... jut how long did the creation of the universe take?...
One BIG bang, or a series of "Firework display" type smaller explosions......
And how long did the display take place?... (One thing I really WANT to see....)
There is theory that matter/anti-matter "explosions" and yes I know I just posted on this in another thread, there is theory that they created this "Big Bang", and that was the creation of the universe, and the energy released created the big explosion we know as the big bang, and that the universe expands.
I have theorised that as the speed of light is a known constant, it is quite possible that this was not a solitary event, and there is many more than just one universe, just so far apart, we have not had enough time for these "Bubbles" of universe to interact, and for that reason we have not observed these other universes....
That has been taken as a "we just dont know".
However, the current "Age of the universe" is a "probable" and its taken as read that if anyone can come up with a more accurate figure, we will all adopt that, as long as there is reasonable documentation into why.
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Post by ukjonas on Nov 9, 2012 10:57:06 GMT
SubductionZone, in some of his replies to a poster on the MB boards (cant remember his name), mentioned a website Physics Forums [ www.physicsforums.com/index.php ] I have visited this and I have read a lot of the posts in the cosmology sub-forum and whilst some of it a bit above my understanding (mainly the math), most of it explains it very clearly... The contributors there do go out of there way to explain stuff clearly and they certainly know their stuff. Worth a look  |
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Post by unavailable on Nov 13, 2012 16:59:24 GMT
I think that the term Big Bang still brings to mind an explosion where the force of the explosion forces material away from the center. The correct term is " Sudden Expansion of the Universe" If you look at it as all the matter and energy in our Universe condensed into the size of a point, then the gravity of this body would have stifled any expansion type radiation. A force greater than the gravity forced it apart. Smaller bodies Black Holes are proof that given enough mass and when the density of this mass reaches a crytical point nothing escapes from the Black Hole. There was an interesting thread about this on the old MB boards. Basically, the universe didn't 'expand' in the moments after the BB, it 'inflated'. The inflation occurred due to the continuing conversion of energy to matter. If the initial point was pure energy, there was no space and no gravity which is why it's said that time and space began with the BB. When some of that energy converted to matter, it created space and gravity. As more matter was created, so was more space which resulted in inflation. The creation of space between existing objects happened faster than light could travel between the objects so it appeared that the universe expanded faster than light. |
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Post by privatepaddy on Nov 14, 2012 3:30:43 GMT
I think that the term Big Bang still brings to mind an explosion where the force of the explosion forces material away from the center. The correct term is " Sudden Expansion of the Universe" If you look at it as all the matter and energy in our Universe condensed into the size of a point, then the gravity of this body would have stifled any expansion type radiation. A force greater than the gravity forced it apart. Smaller bodies Black Holes are proof that given enough mass and when the density of this mass reaches a crytical point nothing escapes from the Black Hole. There was an interesting thread about this on the old MB boards. Basically, the universe didn't 'expand' in the moments after the BB, it 'inflated'. The inflation occurred due to the continuing conversion of energy to matter. If the initial point was pure energy, there was no space and no gravity which is why it's said that time and space began with the BB. When some of that energy converted to matter, it created space and gravity. As more matter was created, so was more space which resulted in inflation. The creation of space between existing objects happened faster than light could travel between the objects so it appeared that the universe expanded faster than light. I don't remember that particular thread and it appears that some of the knowledgeable that explained such things did not get aboard this life boat. According to Wiki the force of gravity parted from the other forces at about 10^- 43 seconds, at the end of the plank epoch period of the BB. Since the equivalence principle where energy exerts a gravitational force should apply to the inflationary period I would think that what ever this inflationary force is it overcame the force of gravity of everything in our universe.  |
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Post by freegan on Nov 14, 2012 8:28:04 GMT
I think that the term Big Bang still brings to mind an explosion where the force of the explosion forces material away from the center. The correct term is "Sudden Expansion of the Universe" If you look at it as all the matter and energy in our Universe condensed into the size of a point, then the gravity of this body would have stifled any expansion type radiation. A force greater than the gravity forced it apart. Smaller bodies Black Holes are proof that given enough mass and when the density of this mass reaches a crytical point nothing escapes from the Black Hole. This interpretation, I suspect, stems from an invalid perspective. From outside the Black Hole, it appears to us that gravity is 'the irresistible force' but 'within' the singularity all bets are off. The singularity exists in a quantum domain just as the Universe exists in its own Space/Time and here there is no valid external perspective. There is a long standing hypothesis, that enchants me, that the Universe is a Black Hole within a 'mother universe' and Black Holes within our Universe are 'daughter universes'. The 'mechanism' that I envisage for this is that, because the singularity exists in a quantum state, it has access to all the 'dimensions'* hidden from us and can self-organize its own space-time. Once it has established its own space-time it now has mutually entangled particles with which it can self-organize (by Quantum Computing) its own 'laws of physics' (including its gravitational constant) to ensure its 'fertility' at a later stage of its development. In this scenario we are no longer the arrogant anthropocentric 'purpose of the Universe's existence' but merely a component part in an 'organic' process. It is this perspective that I find so enchanting and humbling. [ * I use the term 'dimensions' figuratively because I suspect that our perception does not delve, yet, far enough beyond the recognition of the existence of quarks and that these are only 'shadows' of a deeper reality.] |
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Post by silverdragon on Nov 14, 2012 8:49:05 GMT
Hmm... space is not empty.
There is no such thing as "Nothing"?......................
Ok, some thoughts,
We are affected by Gravity.... from the Sun.....
Therefore, if you think that through, there MUST be some form of communication between the sun and Earth?....(Other than the flow of energy and light?...)
In the same way, what stops us flying away from the Milky Way?....
Gravity keeps all objects in the milky way PART of the milky way.....
Therefore, there MUST be communication between the parts of the milky way.
This must be, as far as we can work out, some form of electron flow, proton flow, or SOMETHING....
Just what IS that gravitational force anyway?...
Lets start with a Magnet pair... we KNOW they attract... but how?...
There is, after all, nothing between them?....
So how does one magnet KNOW there is another magnet "Close", how does t know what to attract?...
Take that bigger... we know there is a magnetic forcefield around the earth, we know that because we use it in Compasses etc.
So... is it the same with Gravity?....
Is there a gravitational forcefield we just cant "see" at the moment?...
In that case, there must be "Something" in space, that communication MUST be something that flows between different spacial bodies...
So this idea of the universe being full of nothing between the spacial bodies is therefore bunkum?...
Can we use that ?.....
Ok, so I was having a mind wander as I wrote this, but I think I may be onto something?....
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Post by Cybermortis on Nov 14, 2012 13:51:28 GMT
Gravity is, according to Einstein's theories, the curvature of space-time caused by anything with mass. The greater the amount of mass the greater the curvature and therefore the greater the gravity.
So following the logic, this could mean that while we view gravity as a 'force' it might just be a side effect of the way the universe is structured and works.
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Post by silverdragon on Nov 15, 2012 7:36:38 GMT
Einstein may have been wrong.
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