Our new Indie Games subforum is now open for business in G&T. Go and check it out, you might land a code for a free game. If you're developing an indie game and want to post about it, follow these directions. If you don't, he'll break your legs! Hahaha! Seriously though.
Our rules have been updated and given their own forum. Go and look at them! They are nice, and there may be new ones that you didn't know about! Hooray for rules! Hooray for The System! Hooray for Conforming!

Gravity is real you dumb fuckers

1235

Posts

  • Deviant HandsDeviant Hands __BANNED USERS
    edited January 2008
    Apothe0sis wrote: »
    But how do we distinguish between a true breakdown in the laws of physics and an upper limit in the human understanding of science?

    Unclear. Rephrase.

    See the above post

    I hope playing the Joker didn't have anything to do with this... I mean, I hope he wasn't driven to kill himself because of the role in some way. He was clearly taking the part pretty goddamned seriously.

    Why so serious?
  • Professor PhobosProfessor Phobos Registered User regular
    edited January 2008
    Guys, I don't understand the idea of a physical law just breaking down. How would that even work?


    Under sufficiently extreme conditions known, predictable behaviors fail. Now normally you can just account for the extremity and compensate- but in the case of, say, a singularity, it is impossible to observe or calculate the effects. So the laws break down as far as we can tell. Obviously they're operating on some unknown laws, but these laws are beyond human observation for the moment and so the human construct of "physical laws" breaks down.

    Basically, the universe isn't broken, but the framework by which we understand it breaks. This is because our understanding is imperfect.

  • AdrienAdrien Registered User
    edited January 2008
    Guys, I don't understand the idea of a physical law just breaking down. How would that even work?


    Under sufficiently extreme conditions known, predictable behaviors fail. Now normally you can just account for the extremity and compensate- but in the case of, say, a singularity, it is impossible to observe or calculate the effects. So the laws break down as far as we can tell. Obviously they're operating on some unknown laws, but these laws are beyond human observation for the moment and so the human construct of "physical laws" breaks down.

    Basically, the universe isn't broken, but the framework by which we understand it breaks. This is because our understanding is imperfect.

    Yeah. Really it's just that things that work the exact same way in every single situation don't sometimes.

    tmkm.jpg
  • Deviant HandsDeviant Hands __BANNED USERS
    edited January 2008
    Adrien wrote: »
    Guys, I don't understand the idea of a physical law just breaking down. How would that even work?


    Under sufficiently extreme conditions known, predictable behaviors fail. Now normally you can just account for the extremity and compensate- but in the case of, say, a singularity, it is impossible to observe or calculate the effects. So the laws break down as far as we can tell. Obviously they're operating on some unknown laws, but these laws are beyond human observation for the moment and so the human construct of "physical laws" breaks down.

    Basically, the universe isn't broken, but the framework by which we understand it breaks. This is because our understanding is imperfect.

    Yeah. Really it's just that things that work the exact same way in every single situation don't sometimes.

    In what cases is this unacceptable

    I hope playing the Joker didn't have anything to do with this... I mean, I hope he wasn't driven to kill himself because of the role in some way. He was clearly taking the part pretty goddamned seriously.

    Why so serious?
  • AdrienAdrien Registered User
    edited January 2008
    Adrien wrote: »
    Guys, I don't understand the idea of a physical law just breaking down. How would that even work?


    Under sufficiently extreme conditions known, predictable behaviors fail. Now normally you can just account for the extremity and compensate- but in the case of, say, a singularity, it is impossible to observe or calculate the effects. So the laws break down as far as we can tell. Obviously they're operating on some unknown laws, but these laws are beyond human observation for the moment and so the human construct of "physical laws" breaks down.

    Basically, the universe isn't broken, but the framework by which we understand it breaks. This is because our understanding is imperfect.

    Yeah. Really it's just that things that work the exact same way in every single situation don't sometimes.

    In what cases is this unacceptable

    Eh?

    We're not saying that singularities are, like, immoral.

    tmkm.jpg
  • shrykeshryke Registered User regular
    edited January 2008
    But how do we distinguish between a true breakdown in the laws of physics and an upper limit in the human understanding of science?
    Ah, the laws never break down even though sci-fi has somewhat abused that term and now it's undergoing extensive counseling.

    By "break down" we mean that you get non-sense results within the model - i.e. X / infinity, X / 0 etc. It's essentially a term we use to say "this is the limit of this model, we need a more detailed thing to properly explain the phenomenon".

    EDIT: A simpler explanation of physical laws breaking down would come from the various approximations used in solid state physics - superconductors for example at first glance appear to be a "break down" of the rules governing conductivity.

    X / infinity = 0.

    Noob.

  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    shryke wrote: »
    But how do we distinguish between a true breakdown in the laws of physics and an upper limit in the human understanding of science?
    Ah, the laws never break down even though sci-fi has somewhat abused that term and now it's undergoing extensive counseling.

    By "break down" we mean that you get non-sense results within the model - i.e. X / infinity, X / 0 etc. It's essentially a term we use to say "this is the limit of this model, we need a more detailed thing to properly explain the phenomenon".

    EDIT: A simpler explanation of physical laws breaking down would come from the various approximations used in solid state physics - superconductors for example at first glance appear to be a "break down" of the rules governing conductivity.

    X / infinity = 0.

    Noob.
    I meant in the context of the model 0 may not be a sensible answer - or may lead to a divide by zero issue. There are plenty of models where you can't put in n = 0 as a starting point.

    Dis' wrote: »
    Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
  • shrykeshryke Registered User regular
    edited January 2008
    shryke wrote: »
    But how do we distinguish between a true breakdown in the laws of physics and an upper limit in the human understanding of science?
    Ah, the laws never break down even though sci-fi has somewhat abused that term and now it's undergoing extensive counseling.

    By "break down" we mean that you get non-sense results within the model - i.e. X / infinity, X / 0 etc. It's essentially a term we use to say "this is the limit of this model, we need a more detailed thing to properly explain the phenomenon".

    EDIT: A simpler explanation of physical laws breaking down would come from the various approximations used in solid state physics - superconductors for example at first glance appear to be a "break down" of the rules governing conductivity.

    X / infinity = 0.

    Noob.
    I meant in the context of the model 0 may not be a sensible answer - or may lead to a divide by zero issue. There are plenty of models where you can't put in n = 0 as a starting point.

    I was being silly anyway.

  • jothkijothki Registered User regular
    edited January 2008
    shryke wrote: »
    But how do we distinguish between a true breakdown in the laws of physics and an upper limit in the human understanding of science?
    Ah, the laws never break down even though sci-fi has somewhat abused that term and now it's undergoing extensive counseling.

    By "break down" we mean that you get non-sense results within the model - i.e. X / infinity, X / 0 etc. It's essentially a term we use to say "this is the limit of this model, we need a more detailed thing to properly explain the phenomenon".

    EDIT: A simpler explanation of physical laws breaking down would come from the various approximations used in solid state physics - superconductors for example at first glance appear to be a "break down" of the rules governing conductivity.

    X / infinity = 0.

    Noob.

    Not quite. Well, it depends on how you define 0 * infinity. If it's 0, then that's wrong. If it's undefined, then you're correct.

    On the other hand, you could just refuse to accept infinity as anything other than a limit, and thus disallow dividing by zero as well. How do mathematicians handle this?

    Edit: Hmm, not all results of multiplications by 0 are also 0, since 0/0 is undefined. (0 * x = 0 => 0 / 0 = x for any x)

    Trying to deal with zero and infinity as constants is weird but strangely compelling. I should probably stop, though.

  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    Well actually in this context it's "what does infinity represent?" to the model.

    In electrodynamics we say a charge at infinity is experiencing 0 interaction with another charge's electric field.

    Dis' wrote: »
    Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
  • shrykeshryke Registered User regular
    edited January 2008
    Yeah, we're dealing with physics here. Infinity is generally just "Big enough that it's not worth dealing with how big anymore".

  • Professor PhobosProfessor Phobos Registered User regular
    edited January 2008
    Adrien wrote: »
    Guys, I don't understand the idea of a physical law just breaking down. How would that even work?


    Under sufficiently extreme conditions known, predictable behaviors fail. Now normally you can just account for the extremity and compensate- but in the case of, say, a singularity, it is impossible to observe or calculate the effects. So the laws break down as far as we can tell. Obviously they're operating on some unknown laws, but these laws are beyond human observation for the moment and so the human construct of "physical laws" breaks down.

    Basically, the universe isn't broken, but the framework by which we understand it breaks. This is because our understanding is imperfect.

    Yeah. Really it's just that things that work the exact same way in every single situation don't sometimes.

    But we know when this happens. It's not some random thing going around undermining the consistency of physical laws. It only happens under specific conditions.

  • The CowThe Cow Registered User
    edited January 2008
    I've gathered that infinity is not, strictly, a number in the same way that 1 or 0 is. It's convenient to say that this horizontal 8 loop will represent infinity and can be manipulated as a number, but it's not actually anywhere on the number line and is in fact all the numbers on every number line, where line may be replaced with plane or any nth dimensional coordinate system, really. This is still as true to physics as it is to mathematics - the infinities of universal volume really are that immense, even assuming a closed geometry. That is, as far as I understand, central to why predictive models begin to break down as the history of the universe is scaled back to this non-existent zero.

    Basically, from Newton onward, you have a series of symbolic equations that are designed to accurately describe what objects, objects being "things we can see that have either energy or mass", will do given certain initial conditions. Even as these objects get smaller and faster, and the ideas behind classical mechanics needs to be revised to understand why things are behaving differently than we expect given otherwise understood initial conditions, that is still basically the goal of physicists - describe the universe as simply and elegantly as possible.

    So at some point most people hear that the universe is expanding and either are shortly thereafter told or themselves conclude that, since things are moving apart, things must have been closer together earlier in time. And since there's no evidence or reason why it shouldn't have always been doing this, just as there is no evidence the expansion will ever stop, what happens when you condense everything that's in the universe into one point?

    The reason there will probably never be a definitive answer to that is that, more or less, physics melts. Math probably melts too. Which sounds retarded but is about as good an answer as any. It's unknown whether there's a finite amount of energy and matter - there is only so much of the universe we can observe, after all. Not that it matters; as the spacetime we are enmeshed in falls down into a 0-dimensional point - which I don't think anyone can actually think about, I'm not saying you're not allowed to so much as it's not something human minds have evolved to think accurately or at all about - the density of the universe approaches infinity. Along the short tail of that approach, physics still holds, we can predict given measured rates of expansion and reverse calculating the rate of compression and calculate estimated densities given a certain universal volume.

    However, once it reaches the singularity, the laws that were formulated to predict the behavior of particles are being applied to situations whose realities are different from the ones they were derived from. Relativistic mechanics was devised to better answer what would happen as very small things started going very fast, and why would an objects speed through space affect its motion through time. It is not equipped to say anything about what happens when the 4 dimensions of length, width, depth, and time have no values whatsoever. On top of that, the fundamental forces - EM, Strong, Weak, and Gravity - cannot act at the point of singularity. There is no space between the nothing that exists for them to act. Even quantum mechanics requires there to be space between protons and neutrons and electrons to probabilistically predict shit. There is literally nothing to describe. So I just say that physics melts and gets all gooey.

    I can appreciate why this is upsetting - what the fuck do you mean, physics doesn't work - but it is In My Humble O, very awesome as well. It is awesome because it eliminates the most annoying questions in metaphysics, what is the prime mover? From Aristotle to Newton to Einstein, it has seemed a fairly universal truth that if something happens, something had to cause it to happen. But what caused the first event to happen to the first thing? Nothing. There is no prime mover. Everything happened to everything else, all at once, and that got everything kind of hot and it had to bust it's nut. Aquinas' celestial prime mover blew his load all over the load he was blowing. Simultaneity, the melodramatically ultimate foe of causality, is a stupidly annoying enough concept when you're dealing with it at relativistic speeds in an already existing, expanded universe.

    Don't ask me what any of this has to do with gravity.

    TL;DR - the theoretical laws you tested and verified on observable phenomenon are being asked to predict events that are occurring in situations that cannot sustain the verification of any physical laws. The prime mover doesn't exist. The universe cannot break because our laws do not generate the universe. Gravity exists because the universe is very lonely and just wants everyone to hang out together. Seriously though, I'm a sophomore and if I'm grossly wrong here I'd appreciate it if someone let me know, if only to get something out of writing that stupid long post.

    In other news, I wrote this whole stupid long post just because I wanted to post up this link to the Simplified Theory of Everything, which I hadn't seen posted yet. He actually has a PhD, dudes. E8! 248 points! Lie Algebras! G4 subalgebras! Triality! I don't know what these mean! The unification of all four fundamental forces in 4 dimensions! Excelsior!

    http://arxiv.org/abs/0711.0770

    Seriously it's got its critics but at least look at it. LOOK AT THE PRETTY PICTURES.

  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    Oh yeah I saw it in NewScientist, assumed it wasn't as good as they were making it out to be and then heard from my brother that apparently a lot of people are saying "well yeah, it's a curve fitting exercise".

    Dis' wrote: »
    Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
  • jungleroomxjungleroomx Aaron Hernandez shot me through the heartRegistered User regular
    edited January 2008
    So I went to go look up what the fuck that Simplified Theory of Everything meant, bit by bit and piece by piece.

    No fucking clue. None.

    Spoiler:
  • L|amaL|ama Registered User regular
    edited January 2008
    jothki wrote: »
    shryke wrote: »
    But how do we distinguish between a true breakdown in the laws of physics and an upper limit in the human understanding of science?
    Ah, the laws never break down even though sci-fi has somewhat abused that term and now it's undergoing extensive counseling.

    By "break down" we mean that you get non-sense results within the model - i.e. X / infinity, X / 0 etc. It's essentially a term we use to say "this is the limit of this model, we need a more detailed thing to properly explain the phenomenon".

    EDIT: A simpler explanation of physical laws breaking down would come from the various approximations used in solid state physics - superconductors for example at first glance appear to be a "break down" of the rules governing conductivity.

    X / infinity = 0.

    Noob.

    Not quite. Well, it depends on how you define 0 * infinity. If it's 0, then that's wrong. If it's undefined, then you're correct.

    On the other hand, you could just refuse to accept infinity as anything other than a limit, and thus disallow dividing by zero as well. How do mathematicians handle this?

    Edit: Hmm, not all results of multiplications by 0 are also 0, since 0/0 is undefined. (0 * x = 0 => 0 / 0 = x for any x)

    Trying to deal with zero and infinity as constants is weird but strangely compelling. I should probably stop, though.

    But 0/0 != x because you can't divide by zero... I think?

    And wouldn't x / infinity be infinitesimally small?

  • ProhassProhass Registered User regular
    edited January 2008
    What about the gravyolies?


    Has...has someone done that already?

  • zakkielzakkiel Registered User
    edited January 2008
    L|ama wrote: »
    jothki wrote: »
    shryke wrote: »
    But how do we distinguish between a true breakdown in the laws of physics and an upper limit in the human understanding of science?
    Ah, the laws never break down even though sci-fi has somewhat abused that term and now it's undergoing extensive counseling.

    By "break down" we mean that you get non-sense results within the model - i.e. X / infinity, X / 0 etc. It's essentially a term we use to say "this is the limit of this model, we need a more detailed thing to properly explain the phenomenon".

    EDIT: A simpler explanation of physical laws breaking down would come from the various approximations used in solid state physics - superconductors for example at first glance appear to be a "break down" of the rules governing conductivity.

    X / infinity = 0.

    Noob.

    Not quite. Well, it depends on how you define 0 * infinity. If it's 0, then that's wrong. If it's undefined, then you're correct.

    On the other hand, you could just refuse to accept infinity as anything other than a limit, and thus disallow dividing by zero as well. How do mathematicians handle this?

    Edit: Hmm, not all results of multiplications by 0 are also 0, since 0/0 is undefined. (0 * x = 0 => 0 / 0 = x for any x)

    Trying to deal with zero and infinity as constants is weird but strangely compelling. I should probably stop, though.

    But 0/0 != x because you can't divide by zero... I think?

    And wouldn't x / infinity be infinitesimally small?

    You can't use infinity in arithmetic operations.

    Smash Bros - 4639-8632-8299 (WA)
  • ScikarScikar Registered User
    edited January 2008
    L|ama wrote: »
    jothki wrote: »
    shryke wrote: »
    But how do we distinguish between a true breakdown in the laws of physics and an upper limit in the human understanding of science?
    Ah, the laws never break down even though sci-fi has somewhat abused that term and now it's undergoing extensive counseling.

    By "break down" we mean that you get non-sense results within the model - i.e. X / infinity, X / 0 etc. It's essentially a term we use to say "this is the limit of this model, we need a more detailed thing to properly explain the phenomenon".

    EDIT: A simpler explanation of physical laws breaking down would come from the various approximations used in solid state physics - superconductors for example at first glance appear to be a "break down" of the rules governing conductivity.

    X / infinity = 0.

    Noob.

    Not quite. Well, it depends on how you define 0 * infinity. If it's 0, then that's wrong. If it's undefined, then you're correct.

    On the other hand, you could just refuse to accept infinity as anything other than a limit, and thus disallow dividing by zero as well. How do mathematicians handle this?

    Edit: Hmm, not all results of multiplications by 0 are also 0, since 0/0 is undefined. (0 * x = 0 => 0 / 0 = x for any x)

    Trying to deal with zero and infinity as constants is weird but strangely compelling. I should probably stop, though.

    But 0/0 != x because you can't divide by zero... I think?

    And wouldn't x / infinity be infinitesimally small?

    When you're dealing with infinity, and division by zero, you can't just say y = x / infinity and then ask what y is. You take a limit, so you look at x divided by bigger and bigger numbers and see what the values tend towards. So you would say y = x / z, and as z tends towards infinity, y tends towards zero. Sometimes you can get perfectly sensible answers out of it, like in the pattern x = 1/2 + 1/4 + 1/8 + 1/16 + ... in which x = 1 at infinity.

    In the particular case of singularities, I don't think breakdown is the correct term. Relativity describes black holes in line with our observations, just when you do the maths you end up with this zero volume point with infinite mass density. This conflicts with quantum mechanics, but it doesn't conflict with observations that we've made of black holes, as far as I'm aware. Just because the maths gets a step more complicated doesn't say "breakdown" to me. This isn't relativity's photoelectric effect.

    ScikarSig2.png
  • SanderJKSanderJK Crocodylus Pontifex Sinterklasicus Madrid, 3000 ADRegistered User regular
    edited January 2008
    Even better, there's nothing wrong with black holes from the outside, at all. Our only problem is that we can't describe what goes on in the center of one. This is problematic, but of no direct consequences. All black holes are the same on the outside apart from 3 parameters: It's mass, it's angular velocity, and (theoretically, in practice all black holes are expected to be neutral) it's charge. Know these 3 things about a black hole, and you know everything there is to know, and predict behaviour near but outside it perfectly. What happens inside doesn't really matter since information cannot get out of a black hole. Of course we want to know, but our laws of physics just don't work when compressed into an infitismal small point.

    Steam: SanderJK Origin: SanderJK
  • Professor PhobosProfessor Phobos Registered User regular
    edited January 2008
    [Honest Ignorance] What about hawking radiation? Can we detect that? [/Honest Ignorance]

  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    [Honest Ignorance] What about hawking radiation? Can we detect that? [/Honest Ignorance]
    As far as I know Hawking radiation hasn't been detected (technically, neither have black holes - I don't know where the whole gravastar idea sits at the moment in competition to them).

    I don't think Hawking radiation tells you anything about what went into the blackhole though since it's the product of matter/antimatter pairs being separated by the event horizon i.e. completely random.

    Dis' wrote: »
    Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
  • SanderJKSanderJK Crocodylus Pontifex Sinterklasicus Madrid, 3000 ADRegistered User regular
    edited January 2008
    Err.... we see stars in the center of our own galaxy circling something at a massive speed, and when you look at it, you see nothing. Now what can be extremely massive (a billion times our sun's mass), small, and completely invisible?

    We also see rontgen bursts from black holes when matter falls into them, as well as the only explanation for pulsars / active galaxies being black holes at the center of galaxies. Every galaxy above a certain size is expected to have a black hole at it's center.

    The existance of black holes really is without a doubt. Of course you can't see them directly, that's the point. There's no doubt what it is either (like dark matter).

    I did some checking, the LHC, again, could show the existance of hawkings radiation. (It can hit 2 particles together hard enough for a mini black hole to form) It seems every physics issue in the world is tied into the results of that thing.

    Steam: SanderJK Origin: SanderJK
  • DrezDrez Registered User regular
    edited January 2008
    They proved GUT with particle accelerators, right? All that remains is TOE?

    steam_sig.png
  • zakkielzakkiel Registered User
    edited January 2008
    Does anyone know how black holes are able to override the Pauli exclusion principle? Or is that one of the points of conflict between QM and relativity?

    Smash Bros - 4639-8632-8299 (WA)
  • Aroused BullAroused Bull Registered User
    edited January 2008
    [Honest Ignorance] What about hawking radiation? Can we detect that? [/Honest Ignorance]
    As far as I know Hawking radiation hasn't been detected (technically, neither have black holes - I don't know where the whole gravastar idea sits at the moment in competition to them).

    I don't think Hawking radiation tells you anything about what went into the blackhole though since it's the product of matter/antimatter pairs being separated by the event horizon i.e. completely random.

    That's correct. Hawking radiation comes from the quantum fluctuations in the vacuum at the edge of the event horizon, when one of the particle/antiparticles in a pair is captured by the black hole. A negative energy particle falls into the black hole, and a positive energy particle escapes, so it looks like the black hole has lost mass (because it absorbed a negative energy particle) and emitted a particle (the escaping positive energy particle), but the particles aren't really being emitted from inside the black hole. That's how I understand it, anyway.

  • AgemAgem Registered User
    edited January 2008
    Drez wrote: »
    They proved GUT with particle accelerators, right? All that remains is TOE?
    If by GUT you mean Grand Unification Theory, no. We've shown electromagnetism and the weak nuclear force to be different facets of the same "electroweak" force (which is a lot more complicated than the way electricity and magnetism are facets of electromagnetism), but we haven't done anything with the strong nuclear force.
    zakkiel wrote: »
    Does anyone know how black holes are able to override the Pauli exclusion principle? Or is that one of the points of conflict between QM and relativity?
    The Pauli exclusion principle can seem to be "overridden" - for example, in a neutron star, the electrons are forced to combine with the proton and become neutrons (although the Pauli exclusion principle still holds for neutrons). It's possible the Pauli exclusion principle doesn't work when we're talking about a black hole, or because it only holds for fermions, maybe the particles are converted into some kind of bosons, or maybe something else entirely. There may be an accepted theory that I don't know about, but we don't really know what happens at a true singularity - we can't know for sure because of the event horizon.

  • Apothe0sisApothe0sis Registered User regular
    edited January 2008
    ArrBeeBee wrote: »
    [Honest Ignorance] What about hawking radiation? Can we detect that? [/Honest Ignorance]
    As far as I know Hawking radiation hasn't been detected (technically, neither have black holes - I don't know where the whole gravastar idea sits at the moment in competition to them).

    I don't think Hawking radiation tells you anything about what went into the blackhole though since it's the product of matter/antimatter pairs being separated by the event horizon i.e. completely random.

    That's correct. Hawking radiation comes from the quantum fluctuations in the vacuum at the edge of the event horizon, when one of the particle/antiparticles in a pair is captured by the black hole. A negative energy particle falls into the black hole, and a positive energy particle escapes, so it looks like the black hole has lost mass (because it absorbed a negative energy particle) and emitted a particle (the escaping positive energy particle), but the particles aren't really being emitted from inside the black hole. That's how I understand it, anyway.

    Now, my extension question is this:

    A consequence of the existence of Hawking Radiation is that black holes evaporate. The theory being the anti-matter part of the VPP combines with matter within the black hole and thus mass is eliminated.
    It is, however, my understanding that when matter and anti-matter combine, a coresponding amounty oof electromagetic radiation is emitted. If it is emitted, then it is done so behind the event horizon - from which it cannot escape. So, where does the mass go?

    What am I missing about Hawking Radiation - I assume my understanding is unnuanced or naive, particular WRT VPPs.

    What I see sees me.
    SODOMISE INTOLERANCE
    Tide goes in. Tide goes out.
  • zakkielzakkiel Registered User
    edited January 2008
    Apothe0sis wrote: »
    ArrBeeBee wrote: »
    [Honest Ignorance] What about hawking radiation? Can we detect that? [/Honest Ignorance]
    As far as I know Hawking radiation hasn't been detected (technically, neither have black holes - I don't know where the whole gravastar idea sits at the moment in competition to them).

    I don't think Hawking radiation tells you anything about what went into the blackhole though since it's the product of matter/antimatter pairs being separated by the event horizon i.e. completely random.

    That's correct. Hawking radiation comes from the quantum fluctuations in the vacuum at the edge of the event horizon, when one of the particle/antiparticles in a pair is captured by the black hole. A negative energy particle falls into the black hole, and a positive energy particle escapes, so it looks like the black hole has lost mass (because it absorbed a negative energy particle) and emitted a particle (the escaping positive energy particle), but the particles aren't really being emitted from inside the black hole. That's how I understand it, anyway.

    Now, my extension question is this:

    A consequence of the existence of Hawking Radiation is that black holes evaporate. The theory being the anti-matter part of the VPP combines with matter within the black hole and thus mass is eliminated.
    It is, however, my understanding that when matter and anti-matter combine, a coresponding amounty oof electromagetic radiation is emitted. If it is emitted, then it is done so behind the event horizon - from which it cannot escape. So, where does the mass go?

    What am I missing about Hawking Radiation - I assume my understanding is unnuanced or naive, particular WRT VPPs.


    As exhaustively discussed in the last physics thread, electromagnetic radiation has no mass, only momentum. In a particle/anti-particle collision, energy and momentum are conserved. Mass is not.

    Smash Bros - 4639-8632-8299 (WA)
  • Apothe0sisApothe0sis Registered User regular
    edited January 2008
    zakkiel wrote: »
    Apothe0sis wrote: »
    ArrBeeBee wrote: »
    [Honest Ignorance] What about hawking radiation? Can we detect that? [/Honest Ignorance]
    As far as I know Hawking radiation hasn't been detected (technically, neither have black holes - I don't know where the whole gravastar idea sits at the moment in competition to them).

    I don't think Hawking radiation tells you anything about what went into the blackhole though since it's the product of matter/antimatter pairs being separated by the event horizon i.e. completely random.

    That's correct. Hawking radiation comes from the quantum fluctuations in the vacuum at the edge of the event horizon, when one of the particle/antiparticles in a pair is captured by the black hole. A negative energy particle falls into the black hole, and a positive energy particle escapes, so it looks like the black hole has lost mass (because it absorbed a negative energy particle) and emitted a particle (the escaping positive energy particle), but the particles aren't really being emitted from inside the black hole. That's how I understand it, anyway.

    Now, my extension question is this:

    A consequence of the existence of Hawking Radiation is that black holes evaporate. The theory being the anti-matter part of the VPP combines with matter within the black hole and thus mass is eliminated.
    It is, however, my understanding that when matter and anti-matter combine, a coresponding amounty oof electromagetic radiation is emitted. If it is emitted, then it is done so behind the event horizon - from which it cannot escape. So, where does the mass go?

    What am I missing about Hawking Radiation - I assume my understanding is unnuanced or naive, particular WRT VPPs.


    As exhaustively discussed in the last physics thread, electromagnetic radiation has no mass, only momentum. In a particle/anti-particle collision, energy and momentum are conserved. Mass is not.

    So...

    Wouldn't this mean that the "evaporation" of a black hole would be far more violent than its rather whimsical name would suggest? In the sense that the mass of the black hole would be reducing slowly, while energy was released within the bounds of the event horizon. Eventually, the mass of the black hole would reduce to a point such that there no longer was an event horizon and EM radiation could now escape.

    As a huge amount of mass would have been converted to energy the release would be rather sudden and a great deal of energy would liberated, like...its own private supernova?

    Or would the energy produced by anti/matter collisions dissipate in some other fashion?

    What I see sees me.
    SODOMISE INTOLERANCE
    Tide goes in. Tide goes out.
  • [Tycho?][Tycho?] Registered User regular
    edited January 2008
    Apothe0sis wrote: »
    zakkiel wrote: »
    Apothe0sis wrote: »
    ArrBeeBee wrote: »
    [Honest Ignorance] What about hawking radiation? Can we detect that? [/Honest Ignorance]
    As far as I know Hawking radiation hasn't been detected (technically, neither have black holes - I don't know where the whole gravastar idea sits at the moment in competition to them).

    I don't think Hawking radiation tells you anything about what went into the blackhole though since it's the product of matter/antimatter pairs being separated by the event horizon i.e. completely random.

    That's correct. Hawking radiation comes from the quantum fluctuations in the vacuum at the edge of the event horizon, when one of the particle/antiparticles in a pair is captured by the black hole. A negative energy particle falls into the black hole, and a positive energy particle escapes, so it looks like the black hole has lost mass (because it absorbed a negative energy particle) and emitted a particle (the escaping positive energy particle), but the particles aren't really being emitted from inside the black hole. That's how I understand it, anyway.

    Now, my extension question is this:

    A consequence of the existence of Hawking Radiation is that black holes evaporate. The theory being the anti-matter part of the VPP combines with matter within the black hole and thus mass is eliminated.
    It is, however, my understanding that when matter and anti-matter combine, a coresponding amounty oof electromagetic radiation is emitted. If it is emitted, then it is done so behind the event horizon - from which it cannot escape. So, where does the mass go?

    What am I missing about Hawking Radiation - I assume my understanding is unnuanced or naive, particular WRT VPPs.


    As exhaustively discussed in the last physics thread, electromagnetic radiation has no mass, only momentum. In a particle/anti-particle collision, energy and momentum are conserved. Mass is not.

    So...

    Wouldn't this mean that the "evaporation" of a black hole would be far more violent than its rather whimsical name would suggest? In the sense that the mass of the black hole would be reducing slowly, while energy was released within the bounds of the event horizon. Eventually, the mass of the black hole would reduce to a point such that there no longer was an event horizon and EM radiation could now escape.

    As a huge amount of mass would have been converted to energy the release would be rather sudden and a great deal of energy would liberated, like...its own private supernova?

    Or would the energy produced by anti/matter collisions dissipate in some other fashion?

    Well, the "evaporation" of black holes is expected to be a non-quiet event if a black hole lost enough mass that it couldn't hold itself together anymore. For a black hole formed by a star this isn't something that would ever happen; its going to be absorbing far more radiation than its emitting at all times, so effectively not going to collapse. However there are things called "primordial black holes". These are theoretical objects that were formed shortly after the big bang, basically tiny black holes. And since they're tiny they can evaporate and blow up unlike their cousins. So, physicists are looking, so far with no success, for the radiation emitted when these primordial black holes die.

    However, I take issue with this whole anti-matter discussion. Hawking radiation does not work because you're throwing anti-matter in, it works because of "virtual particles" which are an entirely different beast, which I must say I do not understand.

    But I dont see why tossing anti-matter into a black hole could cause it to reduce in mass. Oh, EM radiation has no mass you say? Well sure, whatever, but gravity results from energy. Recall E=mc^2 and all that. Throw your anti-matter in, hits normal matter giving you EM radiation, which doesn't escape. Energy is conserved, and the anti-matter has increased the overall energy of the black hole, making it a bit heavier and giving it a bit of a stronger gravitational pull.

    ragesig.jpg

  • Apothe0sisApothe0sis Registered User regular
    edited January 2008
    I cannot mediate upon the question as to whether EM radiation has no mass in this instance (though I am wont to side with Tycho). But I can discuss virtual particles:

    Namely, in the vacuum surrounding a black hole pairs of virtual particles spontaneously spring into being before anihilating each other when they collide. The pair is composed of virtual one partiple and virtual one anti-particle. Virtual particles act like real particles in many respects, but can do "weird" things like having negative kinetic energy. A virtual anti-particle is indeed anti-matter.

    The solution to my question is easy - virtual particles can have negative energy and relative to an external observer particles which are captured by a black hole will do so, while the ones which are not do not.

    Presto chango! It is now clear.

    Now, the question is "What does it mean to have negative energy?" an question to which I do not believe there is an intuitive answer, it's just a situation where the answer is "Do the math, what what".

    What I see sees me.
    SODOMISE INTOLERANCE
    Tide goes in. Tide goes out.
  • zakkielzakkiel Registered User
    edited January 2008
    But I dont see why tossing anti-matter into a black hole could cause it to reduce in mass. Oh, EM radiation has no mass you say? Well sure, whatever, but gravity results from energy.
    Wrong
    Recall E=mc^2 and all that.
    This equation does not mean what you (and apparently many other people here ) think.

    Smash Bros - 4639-8632-8299 (WA)
  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    I don't think Hawking radiation is related to the capture of anti-matter by a blackhole, I believe it's just related to the emission of any type of matter from the event horizon. Since you can't get something from nothing, this means that a black hole has to be losing some amount of its mass as this process goes on.

    Dis' wrote: »
    Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
  • Apothe0sisApothe0sis Registered User regular
    edited January 2008
    Hawking radiation is specifically identified to be in relation to the capture of one member of a virtual particle pair.

    Contrary to my original assessment, it does not relate to anti-particles vs particles but to the fact that any particle captured by a black hole will have negative energy.

    I don't know if that means I agree with you ELM or not.

    What I see sees me.
    SODOMISE INTOLERANCE
    Tide goes in. Tide goes out.
  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    I think it does since energy (i.e. matter) from nothing means there's a deficit that has to be paid by something.

    Dis' wrote: »
    Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
  • AgemAgem Registered User
    edited January 2008
    zakkiel wrote: »
    But I dont see why tossing anti-matter into a black hole could cause it to reduce in mass. Oh, EM radiation has no mass you say? Well sure, whatever, but gravity results from energy.
    Wrong
    Recall E=mc^2 and all that.
    This equation does not mean what you (and apparently many other people here ) think.
    He's not wrong at all. In general relativity, energy causes the curvature of spacetime - in fact, mass is considered to just be a part of energy (E=mc² refers to the energy of a particle or object with mass in its rest frame). In fact, although light doesn't have mass, you can make it act as though it does - if you have an object with a perfectly reflective interior and "trapped" light inside of it, the object would theoretically appear on the outside to be more "massive" (by an absurdly small amount). Similarly, a black hole that was isolated from all particles except for photons that were constantly shot into it would theoretically exhibit a greater gravitational pull (this would be even less obvious, because the spacetime curvature caused by photons would be inconceivably tiny compared to the curvature caused by the pre-existing black hole).

    Light itself is expected to exhibit a gravitational pull, but for a variety of reasons this pull is far too small to detect, at least for now.

  • Salvation122Salvation122 Registered User regular
    edited January 2008
    I'm beginning to understand why they thought you crazy bastards were witches for three hundred years

    Grah my head

    sig.png
  • Premier kakosPremier kakos Registered User, ClubPA regular
    edited January 2008
    Okay. All over the universe, little virtual particle pairs spontaneously pop into existence and then just as quickly annihilate with each other and pop out of existence. The net effect of this occurrence is zero since they only exist for a very brief moment.

    When these little virtual particle pairs pop into existence near a black hole, there's a chance that one will cross the event horizon and one will not. This means that one gets sucked in and the other is free to go. Since it can no longer annihilate with its pair, it gets "promoted" to a real particle in the form of electromagnetic radiation. Since this would violate conservation of energy, a corresponding amount of energy from the black hole "evaporates".

    This means that black holes are losing some amount of energy. The amount they lose due to Hawking Radiation is inversely proportional to their size. The smaller the black hole, the much more energy they lose. If you have a black hole with mass larger than about our moon's mass, then it will absorb more energy than it emits. Smaller than about that mass, then it puts out more energy than it absorbs from cosmic background radiation and will eventually evaporate. How long does this take? A black hole with mass of 10^11 kg will evaporate in about three billion years. The moon is about 10^22 kg.

    SuperKawaiiWillSig.jpg
  • Evil MultifariousEvil Multifarious Registered User regular
    edited January 2008
    That would be a really small black hole.

    When's the estimated heat death of the universe?

    Inquisitor wrote: »
    I fucking hate you Canadians.
Sign In or Register to comment.