Page 7 of 11 FirstFirst ... 234567891011 LastLast
Results 91 to 105 of 160

Thread: Theory of Relativity

  1. #91
    confidentially pleased cacian's Avatar
    Join Date
    Nov 2011
    Location
    London
    Posts
    13,930
    Well if you take babies they are like a capsule of time they increase they are born then again decrease then death.
    It is a capsule of time that grows a certain length then come into being grows even more then dies.
    Time in this sense in finite. Non?
    Or is this not time but something else?
    it may never try
    but when it does it sigh
    it is just that
    good
    it fly

  2. #92
    Registered User
    Join Date
    Aug 2009
    Posts
    3,093
    Quote Originally Posted by Calidore View Post
    If the speed of light is a hard limit, how can space be expanding faster, not to mention accelerating?
    I agree with what Cioran said about "information transfer", this is "standard Bible".

    Why expansion of space is accelerating was a big mystery last time I looked - do a search for "dark energy" to see the latest on this.
    Last edited by mal4mac; 10-24-2012 at 07:49 AM.

  3. #93
    Registered User
    Join Date
    Aug 2009
    Posts
    3,093
    Quote Originally Posted by YesNo View Post
    I agree. I don't know of any explanation that makes sense to me that the big bang should have happened 13.7 billion years ago and not, say 12.5 billion years ago.

    I suppose the way around this is to model that big bangs are happening all the time and we just happen to be on one that started 13.7 billion years ago. Conveniently for such random models, we can't see these other universes so these models are not falsifiable. That would make them more of a belief system rather than a scientific model.
    String theorists have a "landscape model" where each Big Bang model can be thought of as a point in the landscape. This landscape model comes out of basic theory, so I think it qualifies as a scientific theory. It's just there's no experimental proof. But it's no worse a theory than general Relativity was around 1915 - before the experimental proof started to come in (Eddington's solar eclipse mission, etc...)

    String theorists talk about "brane collisions" - each Big Bang is contained on a "membrane", these might interact at some points, and we *might* see these interactions writ large across the sky in distortions of galactic & MBR patterns.

    Maybe CERN will come up with some ideas and see some trace of multiverses in the LHC? It's not a case of "The unicorns will never be seen. It's just a belief system". We might get lucky... or clever...
    Last edited by mal4mac; 10-24-2012 at 08:01 AM.

  4. #94
    Registered User
    Join Date
    Aug 2009
    Posts
    3,093
    Quote Originally Posted by YesNo View Post
    If one were pure energy traveling at the speed of light with respect to any massive, aka inertial, frame of reference, would there be any time or space? I suspect there wouldn't, but I don't know what a physicist would say about that.
    If one were pure energy travelling at the speed of light, one would be very dead, so the experiment would not be possible. That's why Scottie gets all upset when the transport starts to malfunction... Then again Kirk and gang did encounter pure energy beings... ask one of them...

    Imagining that I'm a pure energy being, for the moment, imagine if I blast off to the stars at the speed of light than come back to report to you twenty years later (in your time!) Using the old twin-paradox observations, at the limit, I'd not be a nano-second older. Expanding on this, if I continued always moving at the speed of light, every moment would be the same for me forever. I could be at the stars (and every other star... and every point...) at the same moment (for me). Space would be nothing to me... I'd be everywhere in this moment (and there's only this moment... ) I'll stop now... I'm starting to sound like an E.E. "Doc" Simth novel...

    In summary, I think you're wrong... there would be time and space, but only one moment, and all of space would be the same, that is, reduced to one point.

  5. #95
    Maybe YesNo's Avatar
    Join Date
    Oct 2010
    Location
    Near Chicago, Illinois USA
    Posts
    9,420
    Blog Entries
    2
    Quote Originally Posted by mal4mac View Post
    If one were pure energy travelling at the speed of light, one would be very dead, so the experiment would not be possible. That's why Scottie gets all upset when the transport starts to malfunction... Then again Kirk and gang did encounter pure energy beings... ask one of them...

    Imagining that I'm a pure energy being, for the moment, imagine if I blast off to the stars at the speed of light than come back to report to you twenty years later (in your time!) Using the old twin-paradox observations, at the limit, I'd not be a nano-second older. Expanding on this, if I continued always moving at the speed of light, every moment would be the same for me forever. I could be at the stars (and every other star... and every point...) at the same moment (for me). Space would be nothing to me... I'd be everywhere in this moment (and there's only this moment... ) I'll stop now... I'm starting to sound like an E.E. "Doc" Simth novel...

    In summary, I think you're wrong... there would be time and space, but only one moment, and all of space would be the same, that is, reduced to one point.
    That there would be only one point in the coordinate system is reasonable to me and is all I would be looking for.

    I agree that mass cannot move at that speed. As I understand it trying to accelerate mass not only increases the velocity but also the inertia or mass of the object. Since the object also gets massive as well as increases velocity an incremental change in velocity requires increasing amounts of energy.

    I found this site called "Ask a physicist/mathematician". Here are some questions they answered that were related to what we discussed:

    1) Do time and distance exist in a completely empty universe? http://www.askamathematician.com/201...mpty-universe/ Unless I misread, they left the answer ambiguous.

    2) Does light experience time? http://www.askamathematician.com/201...perience-time/ The answer is no, which is what we agree on.

    They also answered questions such has "How many mathematicians does it take to screw in a light bulb?", which I didn't read.
    Last edited by YesNo; 10-24-2012 at 10:31 AM. Reason: typo

  6. #96
    Maybe YesNo's Avatar
    Join Date
    Oct 2010
    Location
    Near Chicago, Illinois USA
    Posts
    9,420
    Blog Entries
    2
    Quote Originally Posted by mal4mac View Post
    String theorists have a "landscape model" where each Big Bang model can be thought of as a point in the landscape. This landscape model comes out of basic theory, so I think it qualifies as a scientific theory. It's just there's no experimental proof. But it's no worse a theory than general Relativity was around 1915 - before the experimental proof started to come in (Eddington's solar eclipse mission, etc...)

    String theorists talk about "brane collisions" - each Big Bang is contained on a "membrane", these might interact at some points, and we *might* see these interactions writ large across the sky in distortions of galactic & MBR patterns.

    Maybe CERN will come up with some ideas and see some trace of multiverses in the LHC? It's not a case of "The unicorns will never be seen. It's just a belief system". We might get lucky... or clever...
    I would place a belief system, such as the unicorn one you mention, that has no experimental evidence for it, on one side. I would place on the other side a scientific theory, such as relativity, that has evidence in favor of it, on the other side. Between them there are a lot of models and theories and beliefs. It might be possible to come up with some indirect evidence for the multiverse and we need to look for it because the model has been presented, but until there is some evidence, it is not a scientific theory, but a speculation.

  7. #97
    Maybe YesNo's Avatar
    Join Date
    Oct 2010
    Location
    Near Chicago, Illinois USA
    Posts
    9,420
    Blog Entries
    2
    Quote Originally Posted by cacian View Post
    Well if you take babies they are like a capsule of time they increase they are born then again decrease then death.
    It is a capsule of time that grows a certain length then come into being grows even more then dies.
    Time in this sense in finite. Non?
    Or is this not time but something else?
    At least two things people thought were infinite have turned out to be finite.

    Time was believed to be infinite in extent into the past prior to the big bang. Now it is finite. Although time may be assumed to continue indefinitely into the future, that is a different kind of infinity. We haven't reached it yet and so it is not realized.

    Matter was considered to be infinitely divisible in a continuous space modeled by real coordinates of mathematics. Now that we have finite quanta of matter and energy, that coordinate system is only useful as a convenience. It does not represent reality, but our illusion of a continuous space-time.

    I think it is safe to assume that a scientific model should not include any realized infinities. If the mathematics leads to an unbounded state, the scientific theory is no longer valid there.

  8. #98
    Registered User KillCarneyKlans's Avatar
    Join Date
    Mar 2011
    Posts
    35
    Blog Entries
    1
    I was thinking about a book I use to have ... Hawkins on Quatum stuff and describing the quarks as cards ... and spinning them at various turns to reveal the card ... and that got me thinking ... Hey I just saw Groom Lake ... Shatner saved this alien ... that travels at near light speed ... by turning into a gas, gas expands ... so you decide ?!?

    http://en.wikipedia.org/wiki/Spin_%28physics%29
    Quantum mechanics states that component of angular momentum measured along any direction can only take a number of discrete values. The most convenient quantum mechanical description of particle's spin is therefore with a set of complex numbers corresponding to amplitudes of finding a given value of projection of its intrinsic angular momentum on a given axis.

    The spin vector ... is easy to picture classically. For instance, quantum mechanical spin can exhibit phenomena analogous to classical gyroscopic effects. For example, one can exert a kind of >"torque"< on an electron by putting it in a magnetic field (the field acts upon the electron's intrinsic magnetic dipole moment). The result is that the spin vector undergoes precession, just like a classical gyroscope. This phenomenon is used in nuclear magnetic resonance sensing.

    Mathematically, quantum mechanical spin is not described by vectors as in classical angular momentum, but by objects known as spinors. There are subtle differences between the behavior of spinors and vectors under coordinate rotations. For example, rotating a spin-1/2 particle by 360 degrees does not bring it back to the same quantum state, but to the state with the opposite quantum phase;

    http://en.wikipedia.org/wiki/Spin-%C2%BD
    In quantum mechanics, spin is an intrinsic property of all elementary particles. Fermions, the particles that constitute ordinary matter, have half-integer spin ... Particles having net spin ½ include the proton, neutron, electron, neutrino, and quarks. The dynamics of spin-½ objects cannot be accurately described using classical physics; they are among the simplest systems which require quantum mechanics to describe them. As such, the study of the behavior of spin-½ systems forms a central part of quantum mechanics.

    One consequence of the generalized uncertainty principle is that the spin projection operators (which measure the spin along a given direction like x, y, or z), cannot be measured simultaneously. Physically, this means that it is ill defined what axis a particle is spinning about. A measurement of the z-component of spin destroys any information about the x and y components that might previously have been obtained.

    http://en.wikipedia.org/wiki/Lagrangian
    The Lagrangian formulation of mechanics is important not just for its broad applications, but also for its role in advancing deep understanding of physics. Although Lagrange only sought to describe classical mechanics, the action principle that is used to derive the Lagrange equation was later recognized to be applicable to quantum mechanics as well.

    Physical action and quantum-mechanical phase are related via Planck's constant, and the principle of stationary action can be understood in terms of constructive interference of wave functions.

    The same principle, and the Lagrangian formalism, are tied closely to Noether's theorem, which connects physical conserved quantities to continuous symmetries of a physical system.

    Lagrangian mechanics and Noether's theorem together yield a natural formalism for first quantization by including commutators between certain terms of the Lagrangian equations of motion for a physical system.

    In classical mechanics, the natural form of the Lagrangian is defined as the kinetic energy, T, of the system . minus its potential energy, V ... If the Lagrangian of a system is known, then the equations of motion of the system may be obtained by a direct substitution of the expression for the Lagrangian into the >EULER<–Lagrange equation. The Lagrangian of a given system is not unique, but solving any equivalent Lagrangians will give the same equations of motion.

  9. #99
    Maybe YesNo's Avatar
    Join Date
    Oct 2010
    Location
    Near Chicago, Illinois USA
    Posts
    9,420
    Blog Entries
    2
    Quote Originally Posted by KillCarneyKlans View Post
    ... that travels at near light speed ...
    Traveling at light speed implies one has no mass, but it also means space-time is a single point for what is traveling that fast. It makes me wonder if what is traveling at the speed of light could also be considered to be outside space-time.

    I'm reading John S. Rigden's Einstein 1905: The Standard of Greatness now. The goal of the thread is to explain relativity to a child. I'm having a hard time explaining it even to myself. Maybe this book will help.
    Last edited by YesNo; 10-26-2012 at 09:52 PM.

  10. #100
    Registered User
    Join Date
    Aug 2009
    Posts
    3,093
    Quote Originally Posted by YesNo View Post
    Traveling at light speed implies one has no mass...
    But light has energy and therefore, according to E=mc2, it has mass.

    Quote Originally Posted by YesNo View Post
    ... but it also means space-time is a single point for what is traveling that fast.
    If something is a single point how can it be anything?

    String theorists think of particles, ultimately, as one dimensional strings.

    Quote Originally Posted by YesNo View Post
    It makes me wonder if what is traveling at the speed of light could also be considered to be outside space-time.
    Aren't we all outside space time? We can only experience what happens in the present, so we are "outside" the future and the past, therefore outside time. Also conciousness has no location, so it is outside space.

  11. #101
    Maybe YesNo's Avatar
    Join Date
    Oct 2010
    Location
    Near Chicago, Illinois USA
    Posts
    9,420
    Blog Entries
    2
    Quote Originally Posted by mal4mac View Post
    But light has energy and therefore, according to E=mc2, it has mass.
    If light had mass, it couldn't travel at the speed it does. Having mass puts us in an inertial frame of reference with respect to light. That means when we measure light's speed we come up with the same value because of special relativity. Light is not in an inertial frame of reference since it has no inertia. It can't measure the speed of light.


    Quote Originally Posted by mal4mac View Post
    If something is a single point how can it be anything?
    That's what I'm wondering about now, but from the perspective of energy, we already agreed that such energy experiences no space-time. It's coordinate system is a single point. That also seems to be what others acknowledge as well.

    Quote Originally Posted by mal4mac View Post
    Aren't we all outside space time? We can only experience what happens in the present, so we are "outside" the future and the past, therefore outside time. Also conciousness has no location, so it is outside space.
    I would agree with that, but I don't want to go beyond what science is presenting with evidence to back it up.

  12. #102
    Quote Originally Posted by YesNo View Post
    If light had mass, it couldn't travel at the speed it does. Having mass puts us in an inertial frame of reference with respect to light. That means when we measure light's speed we come up with the same value because of special relativity. Light is not in an inertial frame of reference since it has no inertia. It can't measure the speed of light.
    Photons have mass as given by Einstein's equation. They just don't have rest mass.

  13. #103
    Maybe YesNo's Avatar
    Join Date
    Oct 2010
    Location
    Near Chicago, Illinois USA
    Posts
    9,420
    Blog Entries
    2
    Quote Originally Posted by Cioran View Post
    Photons have mass as given by Einstein's equation. They just don't have rest mass.
    OK, I can accept that. Could a photon be considered to have an inertial frame of reference?

  14. #104
    Quote Originally Posted by YesNo View Post
    OK, I can accept that. Could a photon be considered to have an inertial frame of reference?
    Not sure I understand the question. An inertial frame is one in constant uniform motion. That was nothing new with Einstein. It is actually called Galilean relativity, because it goes back to Mr. G. He noted that if you were in constant uniform motion, there is no physical experiment that you could perform that would distinguish this condition from a "rest" state. "Rest" goes in quotes because actually everything is in motion, but some frames are in rest relative to others in motion. The only thing Einstein added to Galilean relativity was the postulate that the speed of light was the same when measured by all inertial frames.

    In the case of light, if light could be said to have a "point of view," the whole history of the world would happen instantaneously, and there would be no distance between any two places. So time and space would collapse away in the photonic frame, as best as I understand it.

  15. #105
    Maybe YesNo's Avatar
    Join Date
    Oct 2010
    Location
    Near Chicago, Illinois USA
    Posts
    9,420
    Blog Entries
    2
    Quote Originally Posted by Cioran View Post
    So time and space would collapse away in the photonic frame, as best as I understand it.
    Yes, that is how I see it as well. It is tempting to think of such energy as being outside space-time. I am not sure that is the way a physicist would see it, however.

Page 7 of 11 FirstFirst ... 234567891011 LastLast

Similar Threads

  1. More on Marx: Critical Theory
    By Ron Price in forum Marx, Karl
    Replies: 5
    Last Post: 11-25-2013, 07:55 AM
  2. When folk theory meets scientific theory?
    By coberst in forum Philosophical Literature
    Replies: 5
    Last Post: 10-20-2009, 02:57 PM
  3. The Marxism and the crisis theory
    By Goethe in forum Philosophical Literature
    Replies: 4
    Last Post: 07-27-2006, 12:43 PM
  4. The Theory of Relativity
    By Lara in forum General Literature
    Replies: 11
    Last Post: 03-08-2004, 01:08 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •