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  1. L

    The arrow of time

    What puzzles me is the time dilation thing. I mean, from an outsider's perspective (us in other words) no object can actually pass over the event horizon but just appears to hover on the edge forever. But black holes feed, and their event horizons grow as they swallow more mass, don't they? We...
  2. L

    Absolute Zero and implications

    Yes, quantum theory states that there will always be a vibration of particles and they can never reach a state of non vibration (like a pendulum can never be perfectly at a rest state) because there will always be tiny fluctuations that don't allow a temperature of absolute zero to be attained...
  3. L

    Virtual particles and quantum fluctuation

    I've always understood (or been led to believe) that virtual particles aren't created in the vacuum but that the vacuum itself is created from virtual particles! These appear and disappear instantaneously thus supposedly not violating the law of conservation of energy but on previous occasions...
  4. L

    Impossible scenario?

    The proton can never achieve c as its mass would have to increase infinitely in order to do so. Even it was accelerated to 99.99% recurring of c it can never achieve c because of its increasing mass. That's because c is the ultimate speed limit in the universe according to GR and is defined by...
  5. L

    Effort to get us all on the same page (balloon analogy)

    If increased redshift is due to greater distance and gravity is of little consequence as you seem to be sayng, is this also true of the redshift of two comparable galaxies of the same distance in which one has been Einstein lensed? In other words will the lensed galaxy be more redshifted than...
  6. L

    Gravitational lensing and red shift

    Are you saying that gravitational fields don't shift light? Do you mean that there is no difference between the redshift of two equidistant galaxies, one of them being lensed by a closer gravitational object? Is this always true or is this because the shift is so small it's undetectable, and if...
  7. L

    Space-time created ahead of matter - how far?

    And yet aren't we constrained by the fact that we cannot accurately predict the future? So isn't this a boundary of sorts, even if it is a localised phenomenon? If as you say the flow of time is purely perceptual, shouldn't we be able to receive information from the future as easily as that from...
  8. L

    Space-time created ahead of matter - how far?

    It's hard for me to get my head round this but does that mean then that different parts of the universe can be in front of or behind each other in terms of the time that has passed, and if so would there be any kind of limit as to how much? In other words are there areas of the universe that are...
  9. L

    Effort to get us all on the same page (balloon analogy)

    A balloon can only expand so far before it bursts as its composition is finite. It's an interesting thought however, that some claim the universe can seemingly expand forever. If so spacetime has a beginning but no apparent end therefore it might or might not say something about the infinite...
  10. L

    Space-time created ahead of matter - how far?

    Yes, I can see how there is no physical boundary condition with relation to space, but surely we have to consider time as well? And yes, two observers are effectively within their own time frame references but the future and the past still exists for them both, doesn't it?
  11. L

    Space-time created ahead of matter - how far?

    By "pre-existing space", do you mean that which existed before spacetime began? Do you think that time and space could have somehow been separated before the Big Bang? Was the BB a convergence of the same? If we run time backwards to the BB doesn't everything converge according to GR? So could...
  12. L

    Space-time created ahead of matter - how far?

    Couldn't the 'outer surface' be defined as the present?
  13. L

    Space-time created ahead of matter - how far?

    Ok. So if the expansion of space is increasing at a faster rate, doesn't that in turn imply that this creation is an ongoing and accelerating process? Is this not closer to what Hoyle envisaged as a process of 'continuous creation'? If the expansion of space is indeed a 'creative' process, from...
  14. L

    If Universe is Expanding at an Accelerated Rate Why

    Thanks Dave. So does this mean that the expansion of space is not uniform? Won't the mass in the universe affect how space expands even if there's not enough of it to halt the expansion? For example, will the intergalactic voids be like bubbles pushing the galaxies on their edges further apart...
  15. L

    What are the limits of redshift?

    Yes, I've read up on the CMB. One thing that puzzles me about the actual size and topology of the observable universe is that everywhere we look when we use deep field observation we are looking towards the origin of the universe even though we can be looking in diametrically opposite...
  16. L

    If Universe is Expanding at an Accelerated Rate Why

    As I understand it, the expansion of space can only be detected from very large intergalactic distances so local expansion would be hard to detect. Expansion is measured by the amount of redshifted light received from galaxies etc which are very distant. And as this expansion is only apparent at...
  17. L

    What are the limits of redshift?

    Interesting comments, thanks. Is there then a way of detecting extremely redshifted light wavelengths that could indicate the presence of objects beyond the visible universe, and would the means of observation need to be purely determined by and limited to time? Observations in the visible light...
  18. L

    Effort to get us all on the same page (balloon analogy)

    Yes, I appreciate the limitations of analogy. So does this mean that the expansion energy of space must have been much greater in the past than the gravity binding the galaxies together, even though they were a lot closer to each other? I've discussed this before on other threads because of...
  19. L

    What are the limits of redshift?

    Does anyone know what the limit is for light from distant objects to be so redshifted that they become undetectable? Could there be a way in detecting objects beyond this barrier? Would any wavelength at all be detectable?
  20. L

    Effort to get us all on the same page (balloon analogy)

    If the universe is expanding into the future doesn't this imply that the future already exists?
  21. L

    Effort to get us all on the same page (balloon analogy)

    The pennies analogy is a good one, although using this analogy, surely the galaxies would have been much closer together and more gravitationally tied to each other in the past as well as being effectively larger in comparison to the total volume of space? Shouldn't they now be more closer...
  22. L

    Effort to get us all on the same page (balloon analogy)

    Isn't the balloon analogy too simplistic? A balloon has to be contained in a bigger dimensional space. So if our universe is expanding doesn't this mean that it has to be expanding into something? Not only this, but on an expanding balloon all points on the surface expand at the same rate...
  23. L

    Existance of time before big bang

    Space can be described geometrically. If time and space are interchangeable, does that mean that time is geometric too? Doesn't it come down to an understanding of dimensionality? To me, an event can't happen in a zero time state. When we talk about quantum fluctuations occurring that spawn...
  24. L

    String Topology and Time

    A very lucid explanation, Mitchell, thanks. But does any of it figure without time? Talk of inflation, vibrations, quantum fluctuations etc, is all well and good but surely they are all dependent on a primal temporal dimension in order to be? To my mind it seems that time needs to be, if not a...
  25. L

    String Topology and Time

    If a point particle is a string viewed end on in three dimensions, or is a zero brane, isn't this merely a perspective? Are open strings really more like ribbons given the dimension of time and are closed strings more like tubes seen end on? If so, could this mean that the string's length is...
  26. L

    Could matter pulled in through a Black Hole be same matter that births a Big Bang?

    If time is no longer applicable in a black hole, how can there be a 'new space-time' or dimension? Don't you really mean that time is no longer applicable inside a singularity?
  27. L

    The paradox, is basically a theory about time travel.

    For all we know, there may be temporally offset parallel universes that are further in front or behind in time relative to the others. Why should they all be happening at the same moment of time? Does string theory have anything to say about this?
  28. L

    Controlled experiment with time.

    I have a problem in accepting that with time dilation the instant of time for both particles is simultaneous and is therefore instantaneous. I don't seem to be getting this point across so I apologise for this. For example, if changes in states are instituted at 1 second intervals and then...
  29. L

    Controlled experiment with time.

    An instant of time cannot be separated by time dilation. However, observers can be separated by time dilation. If one observer is in a separate time frame which has been caused by time dilation, his measurement of time is different to that of the other observer. Each measures his own time with...
  30. L

    Controlled experiment with time.

    If an instant of time is separated by time dilation, how can it be verified as the same instant? Surely an instant can only be compared and verified by synchronous clocks running in the same time frame? Isn't this why there has to be adjustments made in communication satellites etc for even tiny...
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