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Gravity is real you dumb fuckers

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Posts

  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    You know on the plus side I finally worked out the combination of search terms which gives me the answer that yes, it is generally accepted that light has a gravitational field (actually I just realized I should've worked it out from the idea behind that guys time travel experiment, but honestly it was a time travel experiment).

    EDIT: Also at EM - best Dr Who setting ever.

  • zakkielzakkiel Registered User regular
    edited January 2008
    Agem wrote: »
    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.
    So it is. Apologies.

    Smash Bros - 4639-8632-8299 (WA)
  • DouglasDangerDouglasDanger Registered User regular
    edited January 2008
    I thought this was going to be about planes or rockets or crazy people on balloon-chairs D:

    I play games on ps3 and ps4. My PSN is DouglasDanger.
  • shutzshutz Registered User regular
    edited January 2008
    OK, I couldn't bother to read the whole thread, but I did skim it a bit, and there's one thing I saw that kept popping up in the first few pages that irritated me: the comparison of the Big Bang theory to Intelligent Design.

    The thing is, there's no such thing as "just a theory". There's theories that are fertile, and others that lead to nothing.

    Big Bang theory, while not 100% proven, has led to various deductions, corrolaries and lemmas that serve to explain a whole bunch of other things in physics, astrophysics, astronomy, and quantum theory, and some of these things have then been proven experimentally.

    Whereas, Intelligent Design is completely barren: you can't deduce anything useful from it. The problem here is that Intelligent Design forces you into a mindset where "Some god did it." So you can explain anything away with "Some god did it." Which leads to nothing more in the way of knowledge.

    Creativity begets criticism.
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  • Not SarastroNot Sarastro __BANNED USERS regular
    edited January 2008
    shutz wrote: »
    Whereas, Intelligent Design is completely barren: you can't deduce anything useful from it. The problem here is that Intelligent Design forces you into a mindset where "Some god did it." So you can explain anything away with "Some god did it." Which leads to nothing more in the way of knowledge.

    Rubbish, it leads to plenty more in the search for knowledge, as the last few millenia have proven.

    Namely: which god did it?

  • ElJeffeElJeffe Moderator, ClubPA mod
    edited January 2008
    Regarding virtual particles, am I correct in recalling that it was the Heisenberg uncertainty principle that allowed this fuckmuppetry to go on? That normally, the universe barfing out mass/energy from nothing was disallowed, but because it happens so quickly, the entire process falls within the limits of the uncertainty principle, and the universe "doesn't notice", so to speak?

    Or am I misremembering?

    Maddie: "I named my feet. The left one is flip and the right one is flop. Oh, and also I named my flip-flops."

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  • Aroused BullAroused Bull Registered User
    edited January 2008
    ElJeffe wrote: »
    Regarding virtual particles, am I correct in recalling that it was the Heisenberg uncertainty principle that allowed this fuckmuppetry to go on? That normally, the universe barfing out mass/energy from nothing was disallowed, but because it happens so quickly, the entire process falls within the limits of the uncertainty principle, and the universe "doesn't notice", so to speak?

    Or am I misremembering?

    The value of a field and its rate of change with time cannot both be known accurately, the same as the Heisenberg uncertainty principle regarding the position/momentum of particles, although I don't know whether it falls under the same principle or not. For vacuum to be empty, all fields would have to have values of exactly zero, which by extension means they would have a rate of change of exactly zero, which would violate the aforementioned principle as both the value and the rate of change would be known precisely. So you get uncertainty in the form of vacuum fluctuations. As far as I know, energy isn't being created out of nothing, because in any pair of virtual particles, one partner will have positive energy and one will have negative energy, meaning the total energy created is zero.
    I might also be misremembering, but I think that's is the gist of it.

  • zakkielzakkiel Registered User regular
    edited January 2008
    ArrBeeBee wrote: »
    ElJeffe wrote: »
    Regarding virtual particles, am I correct in recalling that it was the Heisenberg uncertainty principle that allowed this fuckmuppetry to go on? That normally, the universe barfing out mass/energy from nothing was disallowed, but because it happens so quickly, the entire process falls within the limits of the uncertainty principle, and the universe "doesn't notice", so to speak?

    Or am I misremembering?

    The value of a field and its rate of change with time cannot both be known accurately, the same as the Heisenberg uncertainty principle regarding the position/momentum of particles, although I don't know whether it falls under the same principle or not. For vacuum to be empty, all fields would have to have values of exactly zero, which by extension means they would have a rate of change of exactly zero, which would violate the aforementioned principle as both the value and the rate of change would be known precisely. So you get uncertainty in the form of vacuum fluctuations. As far as I know, energy isn't being created out of nothing, because in any pair of virtual particles, one partner will have positive energy and one will have negative energy, meaning the total energy created is zero.
    I might also be misremembering, but I think that's is the gist of it.
    Virtual particles in a vacuum appear in matter/anti-matter pairs, not positive/negative energy pairs. This is all right, because they never get detected individually. Except for the case of the black hole, in which one of the pairs develops negative total energy, which is how energy is conserved.

    Smash Bros - 4639-8632-8299 (WA)
  • Aroused BullAroused Bull Registered User
    edited January 2008
    zakkiel wrote: »
    ArrBeeBee wrote: »
    ElJeffe wrote: »
    Regarding virtual particles, am I correct in recalling that it was the Heisenberg uncertainty principle that allowed this fuckmuppetry to go on? That normally, the universe barfing out mass/energy from nothing was disallowed, but because it happens so quickly, the entire process falls within the limits of the uncertainty principle, and the universe "doesn't notice", so to speak?

    Or am I misremembering?

    The value of a field and its rate of change with time cannot both be known accurately, the same as the Heisenberg uncertainty principle regarding the position/momentum of particles, although I don't know whether it falls under the same principle or not. For vacuum to be empty, all fields would have to have values of exactly zero, which by extension means they would have a rate of change of exactly zero, which would violate the aforementioned principle as both the value and the rate of change would be known precisely. So you get uncertainty in the form of vacuum fluctuations. As far as I know, energy isn't being created out of nothing, because in any pair of virtual particles, one partner will have positive energy and one will have negative energy, meaning the total energy created is zero.
    I might also be misremembering, but I think that's is the gist of it.
    Virtual particles in a vacuum appear in matter/anti-matter pairs, not positive/negative energy pairs. This is all right, because they never get detected individually. Except for the case of the black hole, in which one of the pairs develops negative total energy, which is how energy is conserved.
    This is at odds with what I remember. I know that matter particles appear in particle/antiparticle pairs, but if both partners have positive energy then when they annihilate won't that energy be conserved, resulting in energy being created from nothing?

  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    ArrBeeBee wrote: »
    zakkiel wrote: »
    ArrBeeBee wrote: »
    ElJeffe wrote: »
    Regarding virtual particles, am I correct in recalling that it was the Heisenberg uncertainty principle that allowed this fuckmuppetry to go on? That normally, the universe barfing out mass/energy from nothing was disallowed, but because it happens so quickly, the entire process falls within the limits of the uncertainty principle, and the universe "doesn't notice", so to speak?

    Or am I misremembering?

    The value of a field and its rate of change with time cannot both be known accurately, the same as the Heisenberg uncertainty principle regarding the position/momentum of particles, although I don't know whether it falls under the same principle or not. For vacuum to be empty, all fields would have to have values of exactly zero, which by extension means they would have a rate of change of exactly zero, which would violate the aforementioned principle as both the value and the rate of change would be known precisely. So you get uncertainty in the form of vacuum fluctuations. As far as I know, energy isn't being created out of nothing, because in any pair of virtual particles, one partner will have positive energy and one will have negative energy, meaning the total energy created is zero.
    I might also be misremembering, but I think that's is the gist of it.
    Virtual particles in a vacuum appear in matter/anti-matter pairs, not positive/negative energy pairs. This is all right, because they never get detected individually. Except for the case of the black hole, in which one of the pairs develops negative total energy, which is how energy is conserved.
    This is at odds with what I remember. I know that matter particles appear in particle/antiparticle pairs, but if both partners have positive energy then when they annihilate won't that energy be conserved, resulting in energy being created from nothing?

    I believe the process depends on considering intermediate photons - EM is supposed to be propagated by the exchange of virtual photons. So a virtual matter/anti-matter pair annihilates with a total energy proportional to a virtual photon.

    Of course then there's the consideration that all photons can be considered to be virtual as well.

  • UrianUrian __BANNED USERS
    edited January 2008
    Apothe0sis wrote: »
    Urian wrote: »
    [Tycho?] wrote: »
    So, yeah, its pretty damn safe to say that gravity is caused by something. If it isn't then we wont really know anyway.

    I don't see how you can base gravity among the universe based on your understanding of gravity on earth. How do we know science was correct about the universe? We've been on the Moon and Earth, that's it. I just don't think it's fair to assume the ENTIRE rest of the universe is predictable in those ways. There's no way to know.

    Dude, seriously? You're going to try and pull this shit?

    Let's assume you've discovered something which is indeed profound (rather than simply a profound misunderstanding of science) with your statement that our limited experience with gravity (earth and the moon) means that "there's no way to know" about gravity in the universe at large.

    We can state this as a more general principle - we cannot know the appropriateness of a general principle outside the domains and situations in which we arrived at this principle.

    So, we can't know about gravity outside of the moon and earth.

    Let's consider a far simpler principle which is also less controversial and better understood than gravity - "A metal expands when heated".

    So, we've tested that all over Earth and the Moon, and we know why it happens thanks to electron microscopes and physical chemistry and the like. Now, what can we conclude about a metal expanding when heated under a different situation? What about on Mercury? Or Hades Gamma? Or Betegeuse IV? and so on and so forth. Under your maxim, we just cannot know. Which, were the ramifcations of your maxim to stop there would be somewhat workable (but a radically unorthodox view of the role of science).

    The question is, how are we restricting domains? We have concepts such as "Earth" and "The Moon" but we certainly do not believe that the universe operates upon these macro-level and cognitive concepts - so, there's no rational reason to believe that the universe would differentiate its behaviour between domains such as "Earth" and "The Moon" and consequently no mechanism by which we can restrict your maxim in a similar fashion.

    So, now we're dealing with arbitrarily precise positions - we've tested the expansion of metals in some particular position, and another particular position, and so on and so forth. But under your maxim we just cannot know whether metals will behave the same way under temperature in some other place which we haven't tested. So, even on the surface of the Earth, it turns out we can't really conclude anything interesting about metals, except for in areas in which we've already tested their behaviour.

    But wait a minute - why are we assuming that the universe differentiates behaviour solely on position? What if time sensitivity is a factor? What if every 14th minute of every 1400th day metals will actually contract when heated? There's a whole range of time-related factors as well. So, it seems that we can't even predict how any given piece of metal will behave at any given time regardless of metal-related experiences we've had in the past, because we've only had experience with metals at particualr locations at particular times - who knows what will happen next week?

    Then there are countless other variables which might be involved - temperatures used, atmospheric pressure, amount of light in the room, atmospheric composition, the shape of the metal, the size of the metal, the colour of the light in the room, the relative position of Jupiter, the abolute position of Jupiter, the quantum state of nearby cats and so on and so forth.

    So, it seems like your maxim would render science impossible, and yet you're posting with the fruits of science's labour. Oops.

    ----

    TL;DR

    Science and rationality assumes the basic regularity of natural law. As science is by defnition a mechanism by which to make predictions about the future using limited datasets, this assumption is necessary for science and rationality to work*. As such, you can't seriously entertain your objection without invoking radical scepticism, which is bad.

    * Which isn't to say that science cannot deal with irregularity, only that it must assume a basic state of uniformity.

    It makes sense the way you put it. Earth and Moon are two random variables throughout the universe, and we understand how gravity works and is changed on both planets. Chances are, the rest of the universe has a similar if not identical structure of gravity. That works. My whole stance was just that it seems like people desperately want to think they know more than they actually do about the universe, that they would feel better to just think that since we know about gravity on Earth we know about gravity everywhere.

    But your explanation makes sense and I get why it's all predictable. I don't know enough about science to really make stupid claims, it was more of an observation I guess.

    I don't know if you thought I was opposed to science or something, you came off like a dick in that last post. It makes no sense to be opposed to science. That would be being opposed to expanding your mind or using all of the tools available to you in order to evolve humanity. No, my statement was just about how arrogant it would seem for a scientist to think he knows about gravity throughout the universe based on studies on two planets. I don't know where you got me not being thankful for science came from, maybe you just think you're a big man because you're obviously very intelligent in this field and I may not know what im talking about.

  • BoutrosBoutros Registered User
    edited January 2008
    Man, we have telescopes and can observe things all over the place, not just here on earth. We can see the motion of the rest of the solar system and galaxy as well as gravational lensing caused by other galxies and quasars and shit.

  • zakkielzakkiel Registered User regular
    edited January 2008
    This is at odds with what I remember. I know that matter particles appear in particle/antiparticle pairs, but if both partners have positive energy then when they annihilate won't that energy be conserved, resulting in energy being created from nothing?
    Energy levels in a vacuum are not fixed at quantum scales. Virtual particles borrow energy. When they annihilate, the energy disappears. The bigger the loan, the faster they annihilate.

    Smash Bros - 4639-8632-8299 (WA)
  • electricitylikesmeelectricitylikesme Registered User regular
    edited January 2008
    zakkiel wrote: »
    This is at odds with what I remember. I know that matter particles appear in particle/antiparticle pairs, but if both partners have positive energy then when they annihilate won't that energy be conserved, resulting in energy being created from nothing?
    Energy levels in a vacuum are not fixed at quantum scales. Virtual particles borrow energy. When they annihilate, the energy disappears. The bigger the loan, the faster they annihilate.
    I would've thought technically they always borrow the same amount of energy as defined by Heisenberg, it's just a question of how they split that between mass and momentum.

  • grendel824_grendel824_ Registered User
    edited January 2008
    ElJeffe wrote: »
    Regarding virtual particles, am I correct in recalling that it was the Heisenberg uncertainty principle that allowed this fuckmuppetry to go on? That normally, the universe barfing out mass/energy from nothing was disallowed, but because it happens so quickly, the entire process falls within the limits of the uncertainty principle, and the universe "doesn't notice", so to speak?

    Or am I misremembering?

    I think you're misremembering - I've never seen anything relating the HUP with perigenesis before. Not that it never happened, but it's a new one to me and it doesn't sound all that applicable.

  • Apothe0sisApothe0sis Registered User regular
    edited January 2008
    That's absolutely incorrect. HUP is indeed entirely to blame.

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  • jothkijothki Registered User regular
    edited January 2008
    Doesn't the HUP just deal with uncertainty in measurement, not in true value?

  • zakkielzakkiel Registered User regular
    edited January 2008
    jothki wrote: »
    Doesn't the HUP just deal with uncertainty in measurement, not in true value?

    No, or at least, probably not.

    Smash Bros - 4639-8632-8299 (WA)
  • Apothe0sisApothe0sis Registered User regular
    edited January 2008
    Nope. It looks like it's a property of the universe, rather than a practical restriction. And that's certainly a cornerstone of many of our physical theories - it isn't that it's impossible to know, it's that there is nothing to know.

    The best illustration I know of that is in the case of Bose-Einstein Condensates, made famous in popular circles by photon capture experiments. Particles within a super-cooled gas slow down to almost zero, their velocity thus because very well known, their position therefore becomes very uncertain. They start acting weird and you get a new form of matter that acts like it's a giant single nucleus (or atom, I cannot recall exactly).

    Quentin Smith exploits the HUP in one of his cosmological arguments for atheism. It's very compelling.

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  • L|amaL|ama Registered User regular
    edited January 2008
    Haha that sounds cool, have you got a link to it? (the argument)

  • Apothe0sisApothe0sis Registered User regular
    edited January 2008
    This one is his most famous paper which uses the concept.

    http://www.qsmithwmu.com/a_big_bang_cosmological_argument_for_god's_nonexistence_(1992).htm

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