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tommac
2009-Mar-11, 03:44 PM
I was thinking about inflation. Supposedly everything seperated away from everything else at a rate that is faster than our current speed of light right?

If that is the case ... would it be possible that our own perception of time was different than it was now?

For instance if we travelled near the speed of light away from something for 1 year then slowed down to be at the same speed as the other point. Wouldnt we see that we went MUCH farther than one light year? In reality we could have travelled the whole distance of the universe in that one year. Note: that the year we just lived may also have been a million years or more from the external reference point.

Is that how inflation works?

AndrewJ
2009-Mar-11, 05:22 PM
For instance if we travelled near the speed of light away from something for 1 year then slowed down to be at the same speed as the other point. Wouldnt we see that we went MUCH farther than one light year?

I don't think we would see a distance greater than a light year as light from the source (that we moved away from) couldn't have travelled further than one light year in a year. So we would look back at the source one light year away although the co-moving distance would be much greater than this. I think this would apply to the metric expansion of space in general and not just the inflation era to which you refer.


In reality we could have travelled the whole distance of the universe in that one year.

Surely not if space is expanding away behind and in front of you.

tommac
2009-Mar-17, 07:52 PM
I don't think we would see a distance greater than a light year as light from the source (that we moved away from) couldn't have travelled further than one light year in a year. So we would look back at the source one light year away although the co-moving distance would be much greater than this. I think this would apply to the metric expansion of space in general and not just the inflation era to which you refer.



Surely not if space is expanding away behind and in front of you.


Sorry confused here.

OK say the time in our past was moving much quicker(slower??? ) than our time is moving now. Lets say we used to move like time near the EH of a black hole and now we move like time in empty space.

Now we had universal expansion for 1 year ( remember our time is stopped or near stopped to everything outside of our reference zone ) So our 1 year would be equal to MANY years to the observer in empty space.


Now all of a sudden we leave the EH of the black hole. We would see a universe that was created. There would be distances of much greater than one light year away from us.



Here is an easier thought experiment. Hover a spaceship near the EH of a black hole. Shoot a lazer from the spaceship out into deep space towards a detector that is far away ( millions of light years away ). Let the space ship hover at(very near) the EH for 1 year. Now the spaceship quickly flies away from the EH out into deep space( ignore the time it took to get there ) away from any relevant pull from the BH. How far away is the light that he shot?

A quick thought would be that the light is 1 light year away since light can not travel faster than the speed of light. However remember that space-time has been distorted and although the light always was traveling away at the speed of light from our perspective, a distant observer sees us hovering near the black hole for a million years and the light that was emmitted from our spaceship travelled one million light years.

When our spaceship joins the distant observer in deeps space he is amazed at how fast the light traveled away from him. However it was just due to space-time warpage. I remember shooting the lazer one year ago, the observer remembers me shooting it a million years ago we see the same lazer.

So during inflation we could have had a different warpage of time as we do now. Inflation could have been at the speed of light relative to our perception in the past but in the same year ( of our past ) light could have travelled millions of light years.

Argos
2009-Mar-17, 08:17 PM
You understand that the so-called 'inflation era' lasted only a fraction of fraction of a fraction of a second, no?

AndrewJ
2009-Mar-17, 11:30 PM
There's a video on youtube of Alan Guth giving a presentation on cosmic inflation to an astronomy club called skyscrapers. One of the astronomers asks Guth if the speed of light was the same then as now. Guth replies that we cannot assume that the laws of physics were then the same but we have no other laws to test the model against and there is no reason to believe special relativity is violated.

As another poster said, inflation lasted a yoctosecond (or whatever). However, it's a scenario worth considering given that far distant space is expanding faster than c right now.

tommac
2009-Mar-18, 02:37 AM
You understand that the so-called 'inflation era' lasted only a fraction of fraction of a fraction of a second, no?


Doesnt matter ... a fraction of a second at just outside the EH of a black hole can equal billions of years for a distant observer.

In that fraction of a second the whole universe could have been created out to billions of light years. If our time was warped enough.

tommac
2009-Mar-18, 02:47 AM
There's a video on youtube of Alan Guth giving a presentation on cosmic inflation to an astronomy club called skyscrapers. One of the astronomers asks Guth if the speed of light was the same then as now. Guth replies that we cannot assume that the laws of physics were then the same but we have no other laws to test the model against and there is no reason to believe special relativity is violated.

As another poster said, inflation lasted a yoctosecond (or whatever). However, it's a scenario worth considering given that far distant space is expanding faster than c right now.

My question assumes relativistic SOL at current speeds. Light is always travelling at the speed of light for me, never faster, never slower.

When I am at the EH of a black hole and shoot my laser ... the laser travels away from me at the speed of light ...

Now there is a bit of an illusion as I leave the gravitational field. Because light although travelling at the speed of light away from me but the distance between me and the light is growing becuase of my warping of space time.


Take two clocks started at the same time. Move one to the EH of a black hole and shoot a lazer and mark down the time that the lazer was shot. Bring the clock away from the BH back to the starting point where the other clock is. Compare their times ... they are very different. Look at how far the laser is from the BH and it will be much farther away than SOL in the current relative time would allow.

The key here is that our flow of time has not always been at the same rate and in fact our perception of space has not always been the same. This is why our laser, or in the case of inflation everything, can seperate at faster than the speed of light in our current perception of space-time allows

tommac
2009-Mar-18, 02:52 AM
As another poster said, inflation lasted a yoctosecond (or whatever). However, it's a scenario worth considering given that far distant space is expanding faster than c right now.
Can a yoctosecond in a strong gravitational field be equal to the hubble radius / speed of light in a weak gravitational field.

ys = hr/C ?

AndrewJ
2009-Mar-18, 04:40 AM
I would agree that our perception of time and space changes relative to frame of reference and you give examples of time dilation and simultaneity. From what I have read, special relativity is maintained in space expanding superluminally in that communication cannot occur between points expanding apart faster than c.


Can a yoctosecond in a strong gravitational field be equal to the hubble radius / speed of light in a weak gravitational field.

ys = hr/C ?

It would be a strong accelaration that could dilate a time period of billions of years down to a yoctosecond.

Cougar
2009-Mar-18, 01:26 PM
For instance if we travelled near the speed of light away from something for 1 year then slowed down to be at the same speed as the other point. Wouldnt we see that we went MUCH farther than one light year? In reality we could have travelled the whole distance of the universe in that one year. Note: that the year we just lived may also have been a million years or more from the external reference point.

Is that how inflation works?

No.

tommac
2009-Mar-18, 02:21 PM
I would agree that our perception of time and space changes relative to frame of reference and you give examples of time dilation and simultaneity. From what I have read, special relativity is maintained in space expanding superluminally in that communication cannot occur between points expanding apart faster than c.

Well info from galaxies that are moving away superluminally eventually reach us, so they do "communicate" to us.




It would be a strong accelaration that could dilate a time period of billions of years down to a yoctosecond. Strong but possible. In fact all black holes are capable of this time dilation.

AndrewJ
2009-Mar-18, 05:25 PM
Well info from galaxies that are moving away superluminally eventually reach us, so they do "communicate" to us.

That we detect EMR from such galaxies is due to cosmic expansion initially decelerating because of gravity before accelarating because of dark/vacuum energy. The radiation was in space sufficiently decelerated to an expansion velocity below c (such that the photons were not hopelessly swimming against the tide) for long enough that it became encompassed within the expanding boundary of the Hubble Volume. Within this sphere special relativity undoubtedly applies, c is supreme and the plucky little photons will eventually reach us. Whilst such galaxies detected may right now be receding superluminally they would be undetectable had their recession from us always been faster than c.


Strong but possible. In fact all black holes are capable of this time dilation.

Black holes seem remote, exotic things. All-pervasive phenomena like dark energy and dark matter strike me as more compelling. I really don't know what relativistic effects you would get at an Event Horizon. Perhaps if you rephrased the question one of the more senior members could give you an answer. Right now, it seems as if you'll just get advised that inflation applied very briefly to a miniscule universe.

tommac
2009-Mar-18, 05:38 PM
That we detect EMR from such galaxies is due to cosmic expansion initially decelerating because of gravity before accelarating because of dark/vacuum energy. The radiation was in space sufficiently decelerated to an expansion velocity below c (such that the photons were not hopelessly swimming against the tide) for long enough that it became encompassed within the expanding boundary of the Hubble Volume. Within this sphere special relativity undoubtedly applies, c is supreme and the plucky little photons will eventually reach us. Whilst such galaxies detected may right now be receding superluminally they would be undetectable had their recession from us always been faster than c.

Light from a galaxy that is receeding from us currently at superluminal speeds will still get to us. Please refer to ant and rope.





Black holes seem remote, exotic things. All-pervasive phenomena like dark energy and dark matter strike me as more compelling. I really don't know what relativistic effects you would get at an Event Horizon. Perhaps if you rephrased the question one of the more senior members could give you an answer. Right now, it seems as if you'll just get advised that inflation applied very briefly to a miniscule universe.

No again this is not the question and I admit that this part of the question may lean into ATM ... athough I am asking it not inferring it.

The point is that the dilation of time in our past could provide an illusion of superluminal expansion during the period that we call inflation.

Us trying to examine inflation from our time does not make sense to us because it would appear that everything expanded superluminally. However there is no need for superluminal expansion if our reference time changed signifigantly during that period.

AndrewJ
2009-Mar-18, 06:02 PM
Light from a galaxy that is receeding from us currently at superluminal speeds will still get to us. Please refer to ant and rope.

Sorry to highjack your thread. I had assumed that the ant on a rubber rope thing was a presentation of Xeno's Paradox - "if a frog jumps from the bank and each jump is half the previous one will it reach the lillypad?", and calculus tells us the answer is no. How does the photon get to us if space is expanding faster than the ground the photon can cover?

My previous answers were unaware that communication was possible between objects receding superluminally so please disregard.

tommac
2009-Mar-18, 06:06 PM
Sorry to highjack your thread. I had assumed that the ant on a rubber rope thing was a presentation of Xeno's Paradox - "if a frog jumps from the bank and each jump is half the previous one will it reach the lillypad?", and calculus tells us the answer is no. How does the photon get to us if space is expanding faster than the ground the photon can cover?.

The ant and the rope thread on baut is probably my favorite baut thread. Definitely worth a read if you are not familiar with ant and the rope.

AndrewJ
2009-Mar-18, 07:12 PM
The ant and the rope thread on baut is probably my favorite baut thread. Definitely worth a read if you are not familiar with ant and the rope.

I've had a think about this at my company's expense. I haven't read the thread as I assume it would be maths heavy. I see that conditions for the ant would be different for the hare, frog or whichever symbol of Xeno's paradox never gets there as the rubber stretching (expansion) diminishes as the ant/photon progresses. Transferred to the frog-hopping-to-the-lillypad analogy, rather than each of the frog's thrusts being always half the previous one it might be consecutively two-thirds, then four-fifths and the frog could make it. So, I guess you don't need deceleration for a photon to transverse superluminally expanding space. Thanks! You learn something new every day!

I assume that, as you suggest, when looking at such a galaxy time would dilate and length contract such that special relativity is sustained. If we cannot say "communication cannot occur between points expanding apart faster than c" it might be amended to "communication cannot be seen to occur between points expanding apart faster than c". I would imagine that any such galaxy would only be receding a lttle faster than c for there to be time in the age of the universe for its EMR to have battled its way to us. Would it be the case that most galaxies currently receding superluminally had at one time decelerated?