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Thread: The Planck scale

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    The Planck scale

    It seems, from what I understand, that by combing fundamental constants we can arrive at some measurements that may have some deep physocal significance. For example, the Planck length:

    2bdff45e72accaa07432ca6acaa23f96.png
    (courtesy wiki media)

    may be the smallest possible physical length which has any meaning, according to some models. Similarly, Planck time (about 5.4 x 10^-44 s), discusses in another thread, has a similar significance.

    Then there is the Planck mass, about 2.2 x 10^-8 kg ... wait what? 22 micrograms? That's huge! You can see 22 g of stuff without a microscope! Does the Planck mass have any metaphysical significance like its siblings do, or is it just a trick of dimensional analysis?

    Nick

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    Quote Originally Posted by Nick Theodorakis View Post
    It seems, from what I understand, that by combing fundamental constants we can arrive at some measurements that may have some deep physocal significance. For example, the Planck length:

    2bdff45e72accaa07432ca6acaa23f96.png
    (courtesy wiki media)

    may be the smallest possible physical length which has any meaning, according to some models. Similarly, Planck time (about 5.4 x 10^-44 s), discusses in another thread, has a similar significance.

    Then there is the Planck mass, about 2.2 x 10^-8 kg ... wait what? 22 micrograms? That's huge! You can see 22 g of stuff without a microscope! Does the Planck mass have any metaphysical significance like its siblings do, or is it just a trick of dimensional analysis?

    Nick
    Well, the Planck Energy is also very large.

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    Personally, but this is just speculation, I think the Planck Mass could be the lower limit of a concentrated mass in GR which can be predicted fundamentally by QM. Otherwise, we are still left with the problem why particles are so small and why the Planck Mass should be fundamental.

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    Quote Originally Posted by Aethelwulf View Post
    Personally, but this is just speculation, I think the Planck Mass could be the lower limit of a concentrated mass in GR which can be predicted fundamentally by QM. ...
    If we're speculating... maybe it is the lowest mass/energy for a particle that can't virtually exist longer than Planck Time. I'm sure someone who actually knows will be along soon.
    Forming opinions as we speak

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    Quote Originally Posted by antoniseb View Post
    If we're speculating... maybe it is the lowest mass/energy for a particle that can't virtually exist longer than Planck Time. I'm sure someone who actually knows will be along soon.
    Hmmm... giving rise to a very high energy.

    That is actually a very concise speculation.

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    Quote Originally Posted by Nick Theodorakis View Post
    It seems, from what I understand, that by combing fundamental constants we can arrive at some measurements that may have some deep physocal significance. For example, the Planck length:

    2bdff45e72accaa07432ca6acaa23f96.png
    (courtesy wiki media)

    may be the smallest possible physical length which has any meaning, according to some models. Similarly, Planck time (about 5.4 x 10^-44 s), discusses in another thread, has a similar significance.

    Then there is the Planck mass, about 2.2 x 10^-8 kg ... wait what? 22 micrograms? That's huge! You can see 22 g of stuff without a microscope! Does the Planck mass have any metaphysical significance like its siblings do, or is it just a trick of dimensional analysis?

    Nick
    How many particles compose that 22 microgram object we are looking at? How big would a single particle with an equivalent mass to this object be? What would it's wavelength be?

    It would have to be a black hole.

    The Plank Mass appears to be the upper bound on the mass of a single particle before it becomes a black hole.

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    Quote Originally Posted by utesfan100 View Post
    How many particles compose that 22 microgram object we are looking at? How big would a single particle with an equivalent mass to this object be? What would it's wavelength be?

    It would have to be a black hole.

    The Plank Mass appears to be the upper bound on the mass of a single particle before it becomes a black hole.
    Ah so I was almost right...

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    Quote Originally Posted by Aethelwulf View Post
    Ah so I was almost right...
    Well, if I were an expert

    Would a plank energy photon be trapped in its own gravitational well?

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    Quote Originally Posted by utesfan100 View Post
    Well, if I were an expert

    Would a plank energy photon be trapped in its own gravitational well?
    Only if it distorts enough spacetime around it I would presume.

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    Quote Originally Posted by utesfan100 View Post
    ... Would a plank energy photon be trapped in its own gravitational well?
    Suppose you said it did, but then someone else observed it from a reference frame in which it was a 1 eV photon? Would that mean it is ambiguous whether something is a black hole?
    Forming opinions as we speak

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    Quote Originally Posted by utesfan100 View Post
    The Plank Mass appears to be the upper bound on the mass of a single particle before it becomes a black hole.
    What do you base this on? The Schwarschild radius for an object with a Planck mass is 2Gm/c^2 or about the Planck length. Now we know that protons are bigger than that - so a super-heavy proton of the Planck mass would not be a black hole. So are electrons larger than that. I would be curious to know what reasoning you applied to get to the statement above.

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    Quote Originally Posted by Shaula View Post
    What do you base this on? The Schwarschild radius for an object with a Planck mass is 2Gm/c^2 or about the Planck length. Now we know that protons are bigger than that - so a super-heavy proton of the Planck mass would not be a black hole. So are electrons larger than that. I would be curious to know what reasoning you applied to get to the statement above.


    An electron is bigger than a proton?


    Rubbish; electrons are much smaller. An electron is pointlike.

    Secondly, if a particle has enough energy, it surely will become a black hole... a photon is very possible to interact at levels lower than the planck length, meaning that it's energy is massively uncertain allowing it to become a Planck Particle - or a black hole in other words.

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    Bad phrasing on my art - an electron is larger than a Planck length is what I meant. And they have effective diameters, defined in several ways. Pointlike is an approximation used for some calculations.

    Secondly, if a particle has enough energy, it surely will become a black hole...
    Show me the maths that says it will. Pretty sure it will not. Because in its rest frame it has not got the mass to become one.

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    Quote Originally Posted by Shaula View Post
    Bad phrasing on my art - an electron is larger than a Planck length is what I meant.
    No it's not because the planck length has... a length. An electron is pointlike.

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    Quote Originally Posted by Shaula View Post
    Show me the maths that says it will. Pretty sure it will not. Because in its rest frame it has not got the mass to become one.

    A Planck particle is a particle whose comptom wavelength if equal to the schwartzschild radius. This sets a relationship as:





    The mass of such a particle is then





    The mass is therefore larger than the Planck mass.

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    Quote Originally Posted by Shaula View Post
    What do you base this on? The Schwarschild radius for an object with a Planck mass is 2Gm/c^2 or about the Planck length. Now we know that protons are bigger than that - so a super-heavy proton of the Planck mass would not be a black hole. So are electrons larger than that. I would be curious to know what reasoning you applied to get to the statement above.
    As Authewolf has pointed out, a larger mass would have a smaller Compton radius. Near the plank mass the two become unified, and a particle of that mass must be a black hole. I would suggest that the mass might be slightly larger than his calculation because his calculation assumes 100% of the mass of a particle is within the Compton radius of its center.

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    Quote Originally Posted by antoniseb View Post
    Suppose you said it did, but then someone else observed it from a reference frame in which it was a 1 eV photon? Would that mean it is ambiguous whether something is a black hole?
    I suppose that, if such a conjecture were put into a demonstrably mathematically cohearant formulation, the correct view would be that all photons define a set of critical frames of reference where they are a plank black hole. This set would be a geometrically invariant object. One side of this set would see the photon as a more massive black hole and the other as a distributed wave.

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    Quote Originally Posted by Aethelwulf View Post
    No it's not because the planck length has... a length. An electron is pointlike.
    It has an effective diameter. If it was a point and had mass then it would have some issues.

    The phrase I was objecting to was:
    Secondly, if a particle has enough energy, it surely will become a black hole...
    This would imply that accelerating a particle was enough to turn it into a black hole. That is not the case AIUI because then you have generated a preferential frame. I have no issues with massive particles doing that - but it has to be the invariant, rest mass that is above a certain limit.

    Utesfan100 - do you know I had never actually seen anything on Planck particles?! Off to read up on them now. It looks like they are a special case of a black hole. Problem with physics - too much to learn, too much to remember!

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    Quote Originally Posted by Shaula View Post
    Utesfan100 - do you know I had never actually seen anything on Planck particles?! Off to read up on them now. It looks like they are a special case of a black hole. Problem with physics - too much to learn, too much to remember!
    1) No known particles, or even confirmed likely blackholes, come close to this limit.
    2) By definition these particles are where our current physics breaks down. Discussion of plank particles is literally extrapolating well beyond the established usefulness of our current models, just to the point we know they must break.
    3) It is likely that new physics will appear here, specifically a quantum theory of gravity.

    Black hole photons would be a special case, if they are even mathematically consistent.

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    I have seen a paper about the shwartzchild proton that suggests that the proton is, in effect, a black hole at the centre of an atom, expaining the strong nuclear force. Maybe this is the link to the Planck mass?

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    Quote Originally Posted by profloater View Post
    I have seen a paper about the shwartzchild proton that suggests that the proton is, in effect, a black hole at the centre of an atom, expaining the strong nuclear force. Maybe this is the link to the Planck mass?
    Given that the strong force is well explained by QCD and doesn't operate on mass (but on colour charge - gluons feel it but are massless, for example) I am unconvinced by this at first glance. You also have the issue that the strong force is way, way stronger than gravity, that QCD explains things like hadronic jets and so on and that the residual strong force (which nucleons feel) is just 'what is left over' from inter-quark forces. Protons have shown structure, which is also inconsistent with a black hole.

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    Quote Originally Posted by profloater View Post
    I have seen a paper about the shwartzchild proton that suggests that the proton is, in effect, a black hole at the centre of an atom, expaining the strong nuclear force. Maybe this is the link to the Planck mass?
    That paper was not met with very high regard and any paper I did show that too, physicists would flat outright say it was rubbish. However with that said, I have something to tell you.

    When I was 20, and still ripely learning physics, I came across the notion that maybe particles where in fact singularities. It sounded like a crazy idea, but at the time I had been reading up on the electron as a ''micro black hole'' which seemed to be a favourable idea at the time because such an object would have a mass and a charge of the electron. Then... about 5 weeks ago I came a across a paper which Einstein had wrote with another scientist.

    This paper explained that geodesic motion due to curved space would not be needed in General Relativity if particles where in fact singularities.

    Now I had dropped that idea many years ago, but reading this paper gave me some faith in this premature idea of mine.

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    Quote Originally Posted by Shaula View Post
    It has an effective diameter. If it was a point and had mass then it would have some issues.

    The phrase I was objecting to was:

    This would imply that accelerating a particle was enough to turn it into a black hole. That is not the case AIUI because then you have generated a preferential frame. I have no issues with massive particles doing that - but it has to be the invariant, rest mass that is above a certain limit.

    Utesfan100 - do you know I had never actually seen anything on Planck particles?! Off to read up on them now. It looks like they are a special case of a black hole. Problem with physics - too much to learn, too much to remember!
    It actually turns out, that I don't agree with the idea of particles being dimensionless - or atleast those particles which are supposed to be truely dimensionless. You see the reason why is because when you extrapolate the energies to account for zero radius sizes of particles, we find the electron actually has an infinite amount of energy:



    basically, what this equation says is, if the radius goes to zero then the electron has an infinite energy which makes up this entire term: which is just the energy density where is the electric field. So, we actually have a serious mathematical inconsistency for pointlike particles. One way to tackle this is by renormalization, but to be honest, many physicists are criticial whether renormalization should be a proper solution. Dirac was well-known for voicing his opinions on renormalization.

    But, whilst that is said, we have a long way to go before we have an understanding of all this stuff. If the electrons energy truely was infinite when not being observed, it would inflate to the size of the pentagon just under one microsecond. I say observed because, particles which are effected by weak measurements will be suspended in time, this is called the zeno effect. I have even a little personal that perhaps the electron does not inflate to these massive energies because it is in constant interaction with particles in the vacuum. But on the same hand I find it difficult to wrap my head round totally zero-dimensional particles.

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    Quote Originally Posted by Shaula View Post

    This would imply that accelerating a particle was enough to turn it into a black hole.
    It's due to the uncertainty principle. If a photon could interact with a planck sized object, the energy would be massively uncertainty and could in theor give rise to a Planck particle.

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    Quote Originally Posted by Shaula View Post
    Given that the strong force is well explained by QCD and doesn't operate on mass (but on colour charge - gluons feel it but are massless, for example) I am unconvinced by this at first glance. You also have the issue that the strong force is way, way stronger than gravity, that QCD explains things like hadronic jets and so on and that the residual strong force (which nucleons feel) is just 'what is left over' from inter-quark forces. Protons have shown structure, which is also inconsistent with a black hole.
    Actually, the paper also attempted to explain the strong force, if my memory serves me right.

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    Quote Originally Posted by profloater View Post
    I have seen a paper about the shwartzchild proton that suggests that the proton is, in effect, a black hole at the centre of an atom, expaining the strong nuclear force. Maybe this is the link to the Planck mass?
    One problem is that if the proton was a black hole then you wouldn't be able to bust it into pieces in something even as powerful as the HLC.

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    Quote Originally Posted by WayneFrancis View Post
    One problem is that if the proton was a black hole then you wouldn't be able to bust it into pieces in something even as powerful as the HLC.
    That's very true.

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    Right ok, my thread on Planck Time gets moved. My thread on the Big Bang gets moved, but this thread remains here.

    I could almost accept the Planck time thread getting moved but the BB thread, then I come in here to see this thread withstanding moderation moving?


    This place is back-to-front.

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    Quote Originally Posted by Aethelwulf View Post
    Right ok, my thread on Planck Time gets moved. My thread on the Big Bang gets moved, but this thread remains here.

    I could almost accept the Planck time thread getting moved but the BB thread, then I come in here to see this thread withstanding moderation moving?


    This place is back-to-front.
    Please stop making off topic posts.

    This thread is here, because the OP is asking a question, not pushing a view. Having said that, if the thread gets too "deep" (beyond the level we aim at for the Q&A section) it too will be moved to the S&T section.

    Please learn the rules and style of a web forum before complaining about it.
    I don't see any Ice Giants.

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    Quote Originally Posted by pzkpfw View Post
    Please stop making off topic posts.

    This thread is here, because the OP is asking a question, not pushing a view. Having said that, if the thread gets too "deep" (beyond the level we aim at for the Q&A section) it too will be moved to the S&T section.

    Please learn the rules and style of a web forum before complaining about it.
    Thank you for replying.

    My Planck Thread on time was not pushing a view. It was a question.

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