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Author Topic: Why can we still measure light from the Big Bang?  (Read 7207 times)

Gerjon de Vries

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Gerjon de Vries asked the Naked Scientists:
   
Hi Team,

For starters, thanks for keeping me informed and entertained on my daily traffic jam visits! Very much appreciated indeed.

Over the last few shows (and some other podcasts) different uses of the background radiaton of the universe were mentioned.

This is something i have difficulty with. As far as i understood this radiation was formed during the big bang and it's a 'sort of' light. Only in a different spectrum.

How is it then that we are still able to measure it? Does it bounce back and forth, is it still being emitted by objects in space? 

Keep up the good work!

Regards,

Gerjon de Vries
Uden, the Netherlands.

What do you think?
« Last Edit: 23/02/2010 12:30:01 by _system »


 

Offline flr

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Why can we still measure light from the Big Bang?
« Reply #1 on: 23/02/2010 23:21:59 »
I thought that "initial" light "formed" everywhere in the "entire" [small for us now] universe shortly after big-bang.
As the universe expanded, that "initial light" was stretched out accordingly, therefore its wavelength became since then larger and larger.     
« Last Edit: 23/02/2010 23:49:00 by flr »
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #2 on: 24/02/2010 06:04:08 »
" CMB (Background radiation) is our telescope into the past "We observe Andromeda, the nearest big galaxy, as it was about 2.5 million years ago". The light reaching Earth is old, the further away the older it is. Once we had what we call the Big Bang.

"When the visible universe was only one hundred millionth its present size, its temperature was 273 million degrees above absolute zero and the density of matter was comparable to the density of air at the Earth's surface. At these high temperatures, the hydrogen was completely ionized into free protons and electrons. Since the universe was so very hot through most of its early history, there were no atoms in the early universe, only free electrons and nuclei. (Nuclei are made of neutrons and protons).

The cosmic microwave background photons easily scatter off of electrons. Thus, photons wandered through the early universe, just as optical light wanders through a dense fog. This process of multiple scattering produces what is called a “thermal” or “blackbody” spectrum of photons. According to the Big Bang theory, the frequency spectrum of the CMB should have this blackbody form. This was indeed measured with tremendous accuracy by the FIRAS experiment on NASA's COBE satellite."

The Hydrogen we now observe in deep space, as well as helium, trace amounts of lithium and beryllium all are remains from that early state. They "were formed as a result of fusion processes going on in the cores of giant stars and in the supernova explosions those stars create when they die.

Small stars like the Sun only fuse hydrogen to helium during their main sequence lifetimes, but eventually fuse helium into carbon when they die, although almost all of this carbon stays in the white dwarf stellar remnant and is not blown out into space. Pretty much every atom we have on Earth heavier than helium is the result of fusion in massive stars that existed earlier in the Universe's history."

Take a look here. Background radiation and WMAP. As well as Finding the Ashes of the First Stars



 
 

Offline Spannerman

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Why can we still measure light from the Big Bang?
« Reply #3 on: 24/02/2010 18:08:25 »
The light that you can see on the surface of the Earth, was sent out from the Sun 8 minutes prior.

<Small Fact> :-)
 

Offline mcvries

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Why can we still measure light from the Big Bang?
« Reply #4 on: 25/02/2010 09:52:07 »
HI all, thanks for the responses, (Gerjon here)

For my understanding, please allow me to try to describe how I understand this.

And let me use the last comment to begin with.
Light takes 8 minutes to travel from the sun to us. So if i wanted to see the light that left there 16 minutes ago, i'd have to measure it 8 minutes beyond earth. Right?

So if i wanted to measure the radiation from the big bang, i'd have to be.... on the border of the universe? To 'get ahead' and capture it?..
Now let's imagine that the sun (as an example) would suddenly stop, as i imagine that happened with the big bang (although suddenly probably has taken quite some time then) and i would like to capture some of it's light (radiation) then it would only be measurable if it bounced back to me from objects (taken the fact that we'd be on an 8 minutes distance and all the light is speeding away from us) or if i got ahead of it in space and time and could look at a sunny sun, but then in the past. If the moment went by that i'd see it go out (for a second time, since i've already seen it from earth) there wouldn't be a sun, there for no light. Unless it reflects of objects. I'd take of, get ahead and see the sun again... and so on and so on.
Back on earth, how would i be able to see the light of the now 'gone' sun? I wouldn't would i?

Or do i have to take in account that the universe is expanding so fast that the formed radiation from then is sort of 'stilled' in place? And there for it's measurable?
And is it then so that is measurable everyweher or is there some boundery as i described in my example with the sun and light?

And now i am going to dive into the second post and the links provided there!
Thanks for all your time so far!
Regards, Gerjon (aka McVries)
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #5 on: 25/02/2010 22:43:47 »
The point of the Big Bang is that there is no 'center' to it. It's not like a point you mark on a map and then say. "That's where it all begun"

The Big Bang has no center, and from each point in the universe it will seem to expand uniformly from you, as if every point you stand on is the absolute center of our universe. Easiest to imagine is to consider yourself standing on a balloon getting inflated. That is a 2D simulation btw, but it captures the effect of every point moving from every other point. So you don't need to go to any 'edge' to observe the phenomena. Wherever you stand in SpaceTime you will be at the 'center' and the edge will be the point from where you no longer can observe any radiation, as all points in space are the exact 'center of the universe' equivalently seen :)

It's kind of confusing I agree, but remember the balloon and also remember that all points are equivalent with this representation. As for the relation between sunlight 'photons' and yourself? You either need to be 'there' already to see that 'older light' of the sun relative Earth, or else you will have to travel faster than the light being 'there' to get to see it if you now left Earth to catch it. Nothing containing anything representing any real information (as that image of the 'older' sun you want to see) can travel faster than this light already have done ('c' in a vacuum).
 

Offline mcvries

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Why can we still measure light from the Big Bang?
« Reply #6 on: 26/02/2010 07:03:17 »
And it seems that there is where i went wrong. I'd heard (and seen) the balloon example and somehow in my mind there still was the notion that there had to be a centre.
I understand that if it expands universally and any point could be the centre as it where that the background radiation from a distant enough point is still on it's way to us, therefore there is still radiation around.

And for my sun centered example, I realise that it would have been impossible, considering the speed of light, but that was the shortest way i could explain what i meant. It was purely hypothetical.

Thanks a lot all so far, it's a lot more logical now to me. (Not that i can say that a big bang which started everywhere and left something that is still expanding is easy to get my head around, but the theoretical part is more comprehensive now)
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #7 on: 26/02/2010 08:08:58 »
Well not really, I'm still kind of stuck on the question as even with this example if we assume a linear 'retardation' of time, tracking it backwards four dimensionally we might end up some where. But you also had an inflation at the BB that makes it 'expand' instantly and if we don't have the map to put that original X on, as there was no SpaceTime before, then there will be impossible to define a center anyway I guess?
==

but you still have to remember that 'balloon' as it is representative of the later 'expansion, and as seen from there you have no center, it's very possible, if so, that inflation worked the same? But even then when shrinking it ?? Awhh :)
« Last Edit: 26/02/2010 08:19:21 by yor_on »
 

Offline mcvries

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Why can we still measure light from the Big Bang?
« Reply #8 on: 26/02/2010 08:23:13 »
Say we tracked it back from one point you'd surely ( i imagine) would end up somewhere, But maybe that somewhere is different for every other point in space. Maybe it there for isn't a single point but a point relatively from where you are now. So it might not be a BigBang as more as an Big Unfold where matter started distributing from a single dimension into multiple. And the original point in the starting situation defines where you are now. What if it wasn't a point, but a long stretched string?

Intriguing, but there is a lot more to read about this and so little time ;-)
I do appreciate to talk about it here, it helps me to find the errors in my way of thinking more easily than reading the same bit over and over again. And this ismore fun!
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #9 on: 26/02/2010 08:34:15 »
Good points :)
 

Offline Robro

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Why can we still measure light from the Big Bang?
« Reply #10 on: 26/02/2010 08:50:33 »
I think that CMB radiation has and always will be here. The idea that it all came from a singularity event is the Big Bong Theory. The balloon or berry cake parable doesn't give the theory justice, because even at 14 - 15 billion years based on redshift/Doppler effect the universe as we see it would have had to expanded at a rate much greater than light speed to achieve the size that it is thought to be, within the theory, presently. If the universe started at a single point, then there must be, without the use of other dimensions, some sort of finite size. If space/time itself is expanding then C must expand along with it, negating the redshift yardstick.
« Last Edit: 28/02/2010 06:21:49 by Robro »
 

Offline mcvries

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Why can we still measure light from the Big Bang?
« Reply #11 on: 26/02/2010 08:57:15 »
Some sort of finite size:
Let's have a thought experiment here: Imagine a single dimension string in a loopback. A circle.
From within that string, bound by the single dimension, there would be no end, but from the 'outside' there would be. For it ends somewhere. I think that we are bound by our own dimensions within those dimensions and the 'finite' part lies on the edge where other dimensions come in play.

By the way, was the fact that the universe expands faster than the speed of light not already proven?
 

Offline Robro

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Why can we still measure light from the Big Bang?
« Reply #12 on: 26/02/2010 09:03:42 »
I don't think that the theory of faster than light expansion has been prooven by the results of any experiment. At least none that I am aware of.
« Last Edit: 28/02/2010 06:24:25 by Robro »
 

Offline mcvries

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Why can we still measure light from the Big Bang?
« Reply #13 on: 26/02/2010 09:43:25 »
Ah okay, because in the podcasts i've listened to thusfar it was more or less presented as a fact.
It should also explain the red shift etcetera..
Ah well, never take anything for granted i suppose.
 

Offline Robro

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Why can we still measure light from the Big Bang?
« Reply #14 on: 26/02/2010 18:31:16 »
Yes it is presented as fact, and that is sad because alot of people buy into the idea of the bigbang, taking it on face value. To me there are way too many things that don't make sense with that theory. The BGBG theory needs constant tweaking, and other evidences are overlooked in order to keep it alive in the schools. It is all mainly because of an interpretation of redshift values from distant galaxies and such, but there are other ways to see redshift other than purely Doppler effect. There is no purpose or cause for the creation theory. Just think about it, the ENTIRE UNIVERSE (even space), squeezing into existence through a volumeless point! I prefer to think outside the established box.
« Last Edit: 28/02/2010 06:36:46 by Robro »
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #15 on: 26/02/2010 20:00:38 »
Before we get any further:)

How about learning where Inflation come from 4_real, as for 'free thinking', well, I think Alan Guth's theory was fairly wild, and free too :) "It is said that there's no such thing as a free lunch. But the universe is the ultimate free lunch". — A. H. Guth

---Quote---

Inflationary theory.
==

Guth's first step to developing his theory of inflation occurred at Cornell in 1978, when he heard a lecture by Robert Dicke about the flatness problem of the universe.[5] Dicke explained how the flatness problem showed that something significant was missing from the Big Bang theory at the time. The fate of the universe depended on its density. If the density of the universe was large enough, it would collapse into a singularity, and if the actual density of the matter in the cosmos was lower than the critical density, the universe would increasingly get much bigger.

The next part in Guth's path came when he saw a lecture by Steven Weinberg in early 1979. Weinberg talked in two lectures about the Grand Unified Theory (GUT) that had been developed since 1974, and how it could explain the huge amount of matter in the universe compared to the amount of antimatter. The GUT explained all the fundamental forces known in science except for gravity. It established that in very hot conditions, such as those after the Big Bang, electromagnetism, the strong nuclear force, and the weak nuclear force were united to form one force. Weinberg also was the one who emphasized the idea that the universe goes through phase transitions, similar to the phases of matter, when going from high energy to low energy. Weinberg’s discussion of why matter is so dominant over anti-matter showed Guth how precise calculations about particles could be obtained by studying the first few seconds of the universe.

Guth decided to solve this problem by suggesting that a supercooling during a delayed phase transition. This seemed very promising for solving the magnetic monopole problem. By the time they came up with that, Guth had gone to the Stanford Linear Accelerator Center for a year, but Guth had been talking to Henry Tye back and forth. Tye suggested that they check that the expansion of the universe not be affected by the supercooling. In the supercooled state, a false vacuum is produced. The false vacuum is a vacuum in the sense that it is state of the lowest possible density of energy; it is false in the sense that it is not a permanent state of being. False vacuums decay, and Guth was to find that the decay of the false vacuum at the beginning of the universe would produce amazing results, namely the exponential expansion of space.

Guth realized from his theory that the reason why the universe appears to be flat was because it was fantastically big, just the same way the spherical Earth appears flat to those on its surface. The observable universe was actually only a very small part of the actual universe. Traditional Big Bang theory found values of omega near one to be puzzling, because any deviations from one would quickly become much, much larger. In inflation theory, no matter where omega starts, it would be driven towards equal to one, because the universe becomes so huge. In fact, a major prediction of inflationary theory is that omega will be found to be one.

The reason for the missing monopoles was that the universe was so big that the density of monopoles would be very low. The “enormous number of monopoles could have risen in the inflationary universe, yet we and all other observers would find them to be observationally far rarer than snowballs in the Sahara…Inflation would spread them so thin that the average observer would expect to find only a single monopole in the entire observable universe.” The incredibly vast expansion of the universe caused by inflation solved both the flatness problem explored by Robert Dicke and the monopole problem that had been explored by Tye and Guth.

By an amazing coincidence, two weeks later, Guth heard about another problem discussed by colleagues at work. This was called the horizon problem. The microwave background radiation discovered by Arno Penzias and Robert Woodrow Wilson appeared extremely uniform, with almost no variance. This seemed very paradoxical because, when the radiation was released about 300,000 years after the Big Bang, the observable universe had a diameter of 90 million light-years. There was no time for one end of the cosmos to communicate with the other end, because energy can not move faster than the speed of light. The paradox was resolved, as Guth soon realized, by the inflation theory. Since inflation started with a far smaller amount of matter than the Big Bang had presupposed, an amount so small that all parts would have been in touch with each other. Inflation then blew up the universe so quickly that there was no time for the essential homogeneity to be broken. The universe after inflation would have been very uniform even though the parts were not still in touch with each other.

Guth first released his ideas on inflation in a seminar at SLAC on January 23, 1980. Word about his ideas spread quickly and soon Guth, who had been worried about his job prospects, was besieged with offers. Although there were positive responses from his audiences, Guth did not publish his work because he was primarily concerned with the “graceful exit” problem. In August, he submitted his paper, entitled “The Inflationary Universe: A Possible Solution to the Horizon and Flatness Problems” to the Physical Review. He ignored magnetic monopoles because they were based on assumptions of GUT, which was outside the scope of the speech.


The answer came on December 1981 while Guth was finishing a paper on his failures. He read a paper from Moscow physicist Andrei Linde saying that the whole universe is within just one bubble, so nothing is destroyed by wall collisions. This conclusion was made using a Higgs field with an energy graph that was originally proposed by Sidney Coleman and Erick Winberg. Guth was amazed by this concept so he searched through Linde’s paper looking for a blunder, but he found none. Linde had independently been working on bubble inflation, but no one had informed him of the flatness problem. Both he and Guth eventually exchanged papers, thus helping each other work out inflation. Another person who was working on the “graceful exit” problem was Paul Steinhardt.
[edit] Confirmation

While inflation was a very interesting theory that was able to solve some existing problems in cosmology, it still needed to be tested. Scientists decided to find out if there is the amount of variation in the background inflation that was predicted by inflationary theory. To accomplish it, they sent two probes to measure the non-uniformities that Guth and Linde said could be found. The results of the first, COBE (Cosmic Background Explorer) were released in 1992 and said “yes.” However, the physicists who sent it felt that they needed to modify their estimates of the experimental uncertainties. COBE was followed in 2003 by WMAP (Wilkinson Microwave Anistropy Probe), which showed that the nonuniformities did exist with even greater precision. This helped show that Guth’s ideas on inflation were the correct ones.

An even more critical test for inflation was: is the value of omega precisely one? According to Guth's inflation theory, omega for the observable universe should equal one, even though it would most likely be much different for the entire universe. In 1998, they accomplished this by measuring the movements of Type Ia supernovae. One thing that they noticed was the supernovae were all the same. They also found out that distant objects actually moved slower than scientists had expected according to Hubble’s expansion law. This suggested the existence of dark energy existing in empty space responsible for the expansion rate of the universe. It was determined from the supernova projects that omega almost certainly equals one, which was in perfect consistency with the inflation model.
[edit] Creating a new universe

Guth has investigated the conditions for how a universe could be created in a laboratory, consistent with the laws of physics. Traditionally, one would need the energy of several galaxies, but inflation theory showed it is actually much easier to create a universe. All one needs is one ounce and false vacuum. Once false vacuum exists, the evolution of the universe is independent of what came before. Physicist Roger Penrose once stated that one would need negative energy to create a new universe, but Guth showed that it could also be made by quantum tunneling.

The birth of a new universe also does not affect the old one. It would take about 10−37 seconds to disconnect from its parent. However, all an observer would see is the formation of a black hole, which would disappear very quickly. Creating a new universe actually would be quite dangerous since it would result in the release of energy similar to that of a 500 kiloton explosion.[citation needed]
[edit] Scientific beliefs

Alan Guth believes that the size of the entire universe is at least 1023 times bigger than the size of the observable universe. The universe also exists among countless other universes with various different laws of physics. A fractal pattern exists in the multiverse system, which involves universes inside vacuums that are inside other universes. Each pocket universe created by inflation will appear flat to the observers within it. Meanwhile, new universes will fill in the gaps created by older ones, similar to Hoyle’s discredited steady-state theory. The big bang of the universe is actually similar to cell division in biology, since new universes are continuously formed. However, inflation always wipes out the circumstances of the beginning of the particular universe.

Alan Guth's main beliefs about the universe are that it definitely has a beginning and that it is just one of many universes that came into existence. Inflation never ends, but keeps expanding at an exponential rate, meaning that it doubles in very short increments much less than one second. Universes keep being created all the time as bubbles within the inflation process. The entire cosmos was created by quantum fluctuations from nothingness. While the concept of a universe being created from nothing sounds improbable, it is perfectly consistent with the laws of conservation of energy because its total energy value is zero."

From Inflation. 
 

Offline Robro

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Why can we still measure light from the Big Bang?
« Reply #16 on: 26/02/2010 22:27:08 »
:) Yes, I have to agree with the 'ultimate free lunch' as there are so many theories, many I'm sure I haven't heard of yet. I'm one that tries to understand the structure of the universe. I don't go along with the curved space/time fabric idea. I see it as a purely mechanical thing with time being a measure of motion. Time dilation being the trade-off of photon cycles for distance. I lean toward theories that have the least dependancy. A path to reality should be crisp and clean, and gas clouds in the distant past in a 'smaller universe' should have been much, much closer together on average than they are observed to be. Powerful telescopes are cool. :)
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #17 on: 27/02/2010 07:31:53 »
Got to admit that I haven't really taken a close look at 'inflation' myself, as my primary interest always have been those strange photons.

But I thought I should, now that we're up and 'running' :)
First of all I think we need to get an idea of what that false vacuum could be that somehow makes it possible according to Adam Guth.

==

"THE FALSE VACUUM arises naturally in any theory that contains scalar fields, that is, fields that resemble electric or magnetic fields except that they have no direction. The Higgs fields of the Standard Model of particle physics or the more speculative grand unified theories are examples of scalar fields. It is typical of Higgs fields that the energy density is minimal not when the field vanishes, but instead at some nonzero value of the field." from False vacuum.
==

And as we know and have proved that the concept of a classical vacuum (Empty, sort of:) is wrong from an quantum mechanical aspect, due to the Casimir effect, this first hypothesis is quite acceptable as space seems to have a hidden 'energy' where space from a QM view could be seen as a field negated by positive and negative energy reaching an equilibrium.

Now, what one have to understand before continuing is that we have 'different' SpaceTimes' depending on how one look. One from a quantum mechanical view of point, another from the classical Newtonian point of view, as I guess yours might be Robro? And then we have the theory of relativity which differs in two approaches, General and Special relativity. We have also the idea of everything ultimately being 'information', as well as the idea of an 'holographic' universe, but both of those raise from the approach of relativity, and QM, as I see it. And there are several others too. Emergence as a approach to it all is the one I like myself :)

Anyway, now we have a glimmer of an idea what that 'false vacuum might be, right? But what was that about a 'scalar field'? A scalar is something "relating to a direction less magnitude (such as mass or speed etc.) that is completely specified by its magnitude" like to tell me that you saw two cars having a speed of fifty miles do tell me something of their speed, but nothing about their direction. There's a lot of fancy words to physics, and it's needed if you want to isolate and talk about 'forces'.

So okay, it's acceptable, to me at least, as a first take on the problem.
Here you can find Alan Guth's own description Alan Guth 2007

There are more to say about it of course :) There always is, right? But it's a start.


« Last Edit: 01/03/2010 12:16:26 by yor_on »
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #18 on: 27/02/2010 08:08:54 »
Thinking some more about it. What it builds on is naturally the slightly modified, so called, 'Standard Model' (lambda-CDM model) of our universe. The Standard model builds on a lot of things like redshift etc. But if we want to take a look at that too, this thread is going to explode in a multitude of different ideas and opinions. Take a look here for a definition of how it is thought that 'dark energy' works in it, expanding our universe. You will know a lot of the standard model when finished with it :) Dark energy and the standard model

I also linked a paper describing a Standard model approach to explaining supermassive black holes (SMBHs) with some nifty photos to it too :). So, the idea still seems to be able to explain most of what we observe today. Super massive Black Holes and the standard model. You don't need the math to get the gist of what the paper says.
==

And this, if you now missed my first links. WAS COSMIC INFLATION THE 'BANG' OF THE BIG BANG? By A. Guth.
« Last Edit: 27/02/2010 08:20:36 by yor_on »
 

Offline mcvries

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Why can we still measure light from the Big Bang?
« Reply #19 on: 27/02/2010 15:21:58 »
I've gotten a lot of homework from this topic thusfar, thanks a lot all!
And because of the language barriere (i'm dutch) it is not the easiests of tasks. **smiles**

 

Offline Robro

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Why can we still measure light from the Big Bang?
« Reply #20 on: 27/02/2010 22:12:25 »
Thank you for the links yor-on, I will look at these various theories to better understand some of the different veiws. Much to read:)
 

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Why can we still measure light from the Big Bang?
« Reply #21 on: 28/02/2010 08:05:14 »
Yeah, it's a habit of mine to link the things I say. "Hey don't blame me, I didn't write it :)" sort of. But that's what cool with this site, it gives such excellent suggestions to what one is missing.. And I have to read it too :(

Ah, that was a joke btw. Not that I read, I know how to do that, I'm sure I do? Anyway...
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #22 on: 28/02/2010 08:58:40 »
This is interesting. Both 'inflation' and the later 'expansion' that pushes the galaxies apart both seem to work through the concept of negative energy. The question there becoming how something that is negative can 'push'? It's often described like having 'invisible boxes' in space, each one containing a negative pressure that then mechanically should press the boxes walls together as I understands it. But still is said to 'press them apart' if this theory should work, right?

---Quote--

The peculiar properties of the false vacuum stem from its pressure, which is large and negative (see box on the right). Mechanically such a negative pressure corresponds to a suction, which does not sound like something that would drive the Universe into a period of rapid expansion. The mechanical effects of pressure, however, depend on pressure differences, so they are unimportant if the pressure is reasonably uniform. According to general relativity, however, there is a gravitational effect that is very important under these circumstances. Pressures, like energy densities, create gravitational fields, and in particular a positive pressure creates an attractive gravitational field. The negative pressure of the false vacuum, therefore, creates a repulsive gravitational field, which is the driving force behind inflation.

--End of quote---

Did you get it?
It's been irritating me for a long time, as I couldn't see how it was thought to work.

"Pressures, like energy densities, create gravitational fields, and in particular a positive pressure creates an attractive gravitational field. The negative pressure of the false vacuum, therefore, creates a repulsive gravitational field, which is the driving force behind inflation."

So a positive pressure acting 'outwards' will create a gravitational field acting inwards. And a negative pressure will then make the gravitational field act outwards? So, anyone have any good links proving this statement? As if I tried to make a vacuum on Earth I wouldn't see a thing would I? As the negative and positive energy takes each others out. But how about a Casimir experiment, creating a negative energy between the walls?

--Quote--Casimir force--

The attractive force occurs because, as quantum theory indicates, even a so-called vacuum contains a multitude of virtual electromagnetic particles and anti-particles in a continuous state of fluctuation. This is known as the vacuum energy.

Because the gap between the plates constrains the possible wavelengths of the virtual particle pairs, there are fewer virtual particles within the space between the plates relative to the space outside them.

This means the energy density between the plates is less than that of the energy density of the surrounding space, creating a negative pressure which pulls the plates together ever so slightly.

---End of quote..

Let's dissect that one. Fewer virtual particles will make a lesser 'energy filled vacuum', okay, that makes sense. And therefore a 'negative pressure' drawing the plates together. Makes sense too. But here comes the clincher. If we now are discussing the same thing 'negative energy' as inflation/expansion does, can we now expect a gravitational field pushing 'space' apart?

And if it does, and it should. Where does the new vacuum comes from? (Crazy ain't it, me treating a vacuum as something 'there' when its a classical 'nothing'. But it has to be 'something' as what we do here creates a new distance in space, and to get a larger distance you will need a 'space' to become larger, if you get my drift?)

Also, will that newly created vacuum contain the same amount of 'energy' as the same distance of vacuum contained, existing before our experiment? Where does those new 'virtual particles' then come from? Are we changing a balance with something unseen for us by our experiment? And is 'expansion' also doing this, if so?

Makes me kind'a love 'emergences' this one :) as if you look at it as an 'emergence', as I like to do, you have some assumptions to do before that. One of them is that we have a symmetry, but unseen to us. That what we see (CPT violations) dark energy, matter etc speaks of an 'unbalance' of SpaceTime have no relevance to the symmetry as it is us that are 'one eyed' when looking at it. We can't see it, but by doing this kind of experiments I see it as we do get a confirmation of it existing 'something' that allows that new 'space' to be constructed inside our SpaceTime. And when we then speaks about 'inflation' and 'expansion' it isn't in a 'nothing' it's happening. We're just (SpaceTime) changing a symmetry/balance. Well, that's how I see it :)
 

Offline yor_on

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Why can we still measure light from the Big Bang?
« Reply #23 on: 03/03/2010 08:05:37 »
Think of space as a waterfall. The edge of it, representing where that 'point of no return' exist will be relative you at all times, no matter where you are. As the expansion fills in 'dots' around every other 'dot' in SpaceTime, all 'dot's' sort of grows away from each other concentrically. And the 'waterfalls edge' will then be that point where those dot's have grown to so many, that the light from outside that 'edge' no longer will have any possibility to reach us.

That is not the same as SpaceTime expanding FTL (faster than light) though, it's more like we have an observable Universe, defined by the time since the BB (Big Bang 13.7 (?) Billion years ago) but inflation and later the expansion might have moved our universe much further than that 'timely definition' as it happened. Remember that the reason why we call the universe a 'flat one' is due to that all distances are so far, that our universe to us seems like a flat one. Just like an ants perspective when climbing around on the ground. I doubt he would agree on Earth being round, although he would complain at all those obstacles existing everywhere, you know, toothpicks etc..

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Why can we still measure light from the Big Bang?
« Reply #23 on: 03/03/2010 08:05:37 »

 

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