8 ms·

Here's a thought experiment that shows that there can't be electrons: "If you had an object with negative charge, then putting that object near a positive char

by FabHK 8y ago

Here's a thought experiment that shows that there can't be electrons: "If you had an object with negative charge, then putting that object near a positive charge would cause it to accelerate towards the positive charge." Getting closer increases the force. "This is a positive feedback loop that immediately results in the object and the positive charge exerting infinite amounts of force on each other, because" getting closer "just leads to applying more force." Thus, there are no electrons. So, I don't think the thought experiment rules out negative mass. In fact, the article explicitly says "if a negative mass was pushed, it would accelerate towards you rather than away from you.", and I assume that if that's an obvious contradiction, the author would have caught it.

thaumasiotes 8y ago
So, electrons are attracted to protons by the electromagnetic force, but they don't make it all the way there because they are repelled by some other force. You don't have a paradox because our model of the electromagnetic force doesn't specify that it's the only force there is. But if a negative mass is moving towards you and encounters a repulsive force, that repulsive force will, by definition, move the negative mass further toward you. It would need to encounter an attractive force to reach equilibrium. Note that, unlike in the electron example, it doesn't matter what kind of force is being applied; the object's negative mass tells us that the response to any repulsive force is acceleration towards the force.
- millstone 8y ago
  > they don't make it all the way there because they are repelled by some other force A repulsive force is not the best way to think about it. The potential of the nucleus is the usual -1/r, and goes to (negative) infinity at zero. A repulsive force would be incorporated into the potential and appear as a bump around the nucleus, and would mess up the electron orbital. A hand-wavy explanation of why the electron doesn't fall in: if you try to push the electrons into the nucleus, you necessarily localize the electron into a smaller volume; this means its wavefunction must get "spikier" and therefore it has more kinetic energy. This kinetic energy rises faster than the potential energy drops, so the state of lowest energy is actually found at an average radius > 0. Note that it took quantum mechanics to rescue the atom. A classical electron could fall into the nucleus. I do not see any problem with a negative-mass particle accelerating towards the force. The analogy with opposite charges seems right to me.
  - btilly 8y ago
    A different hand-wavy explanation. The places that an electron can be found are described by a wave pattern. If the electron is staying in place around a nucleus, that wave pattern has to be a standing wave that reinforces itself. To reinforce itself it has to wrap around the nucleus an integer number of times. This explanation doesn't just explain why it doesn't fall in, it also explains why there are discrete shells that it could be found in, corresponding to how many times it wraps around the nucleus. (It doesn't explain why only a finite number can fit in each shell though. Or why bigger shells can have more electron orbitals. Or...well the actual theory has to be good for something!)
    - drjesusphd 8y ago
      This is the Bohr model of the atom, but was replaced by a proper quantum theory.
      - btilly 8y ago
        Yes. Which is why I called it "a different handwavy theory". And also listed some of the things that it didn't explain.
    - thaumasiotes 8y ago
      I'm not really interested (here) in the reality of the interaction between the electron and the nucleus. I don't think the existence of an electromagnetic field is a good argument against its own existence as argued by FabHK further up. I also don't think FabHK's argument works as an analogy to my problem with negative mass. The electromagnetic field is not self-reinforcing in the same way. Imagine that you're holding a marble of negative glass in your fist. Negative glass is indistinguishable from ordinary glass except that its mass is negative rather than positive. As we all know, the first step in solving any physics problem is to draw a free-body diagram. ( http://www.smbc-comics.com/comics/20130616.png http://www.smbc-comics.com/comics/20130616.png ) Let's draw one here. First, we'll do one for an ordinary marble: 1. The enormous mass of the earth attracts the marble downward proportionately to the marble's mass. 2. The marble cannot accelerate downward, because it's stuck in your fist. Your fist experiences a downward force equal to the weight of the marble. 3. By Newton's third law, your fist exerts an upward force on the marble equal to the force exerted by the marble on your fist. This is exactly equal to the weight of the marble, but in the opposite direction. The two forces cancel, and the marble is at rest. Now for the negative marble: 1. The enormous mass of the earth attracts the marble downward proportionately to the marble's mass. Because that mass is negative, the marble attempts to accelerate upward. 2. The marble can't accelerate upward, because it's stuck in your fist. Your fist experiences an upward force equal to the weight of the marble. 3. By Newton's third law, your fist exerts an downward force on the marble equal to the force exerted by the marble on your fist. This is exactly equal to the weight of the marble, and in the same direction, effectively doubling the marble's weight. The marble is now trying twice as hard to accelerate upward into your fist. 2. (Again.) The marble can't accelerate upward, because it's stuck in your fist. Your fist experiences an upward force equal to double the weight of the marble. Nothing has moved; we're still just trying to work out the balance of forces within the system at rest. 3. (Again.) You can see where this is going. What is the conceptual breakthrough that rescues negative mass from this trap? (Note that saying the marble has negative inertial and gravitational mass, as opposed to negative inertial mass and positive gravitational mass, doesn't help: the marble will be trying to accelerate downward instead of upward, but it will still be doing it with infinite force.)
- vesinisa 8y ago
  > But if a negative mass is moving towards you and encounters a repulsive force, that repulsive force will, by definition, move the negative mass further toward you I am not sure you understand what "repulse" means.. Joking aside, it's easy enough to imagine negative gravity. Do you mean that such counter intuitive behavior would be the natural consequence of negative inertial mass?
- infinity0 8y ago
  > that repulsive force will, by definition, move the negative mass further toward you. only if the repulsive force is negative gravity. If a positive-mass electron attracts a negative-mass electron, the repulsive electromagnetic force will still keep them from making it all the way there.
  - thaumasiotes 8y ago
    >> that repulsive force will, by definition, move the negative mass further toward you. > only if the repulsive force is negative gravity We're talking about negative inertial mass, not negative gravitational mass. Negative inertial mass means accelerating against the direction of any force applied to you, including but not limited to gravity.
deytempo 8y ago
The problem with these papers is there is no compilers to perfectly test the logic except peer review so no one knows if its horse shit or not until someone comes along and comes up with some way to prove it wrong, so I would not be so quick to say “if that’s an obvious contradiction, the author would have caught it”
- phs318u 8y ago
  Physics is highly mathematical and as such, can indeed be "tested" (i.e. proven) to be consistent with mathematical laws. This is fairly straightforward (for suitably mathematically literate people). The real issues are: 1. can the theory make testable predictions that can be verified by observation? e.g. string theory has had issues with this. 2. what does <wierd-mathematical-construct> "mean"? e.g. negative mass, spooky action at a distance, spacetime singularity. In practice, only 1 really matters. However, 2 tends to bug a lot of people (consider the arguments around what the quantum world really represents). I'm one for whom 2 is important. "But what does it really mean?" Back to your original point, looking at the paper [0], it doesn't seem too ridiculously hard to validate the math for someone familiar with this space (see what I did there?), unlike me who has forgotten everything I was taught [1]. [0] https://arxiv.org/pdf/1712.07962.pdf https://arxiv.org/pdf/1712.07962.pdf [1] I have a physics degree but that was 33 years ago and I've been doing nothing but IT since.
  - v_lisivka 8y ago
    1. OpenGL makes good predictions. Why not to switch to OpenGL terms when talking about physics?
    - Retra 8y ago
      Because physicists would find it totally unsuitable for their requirements?
      - v_lisivka 8y ago
        Why match is better for that? To compute prediction, you will need to use computer and compiler, so it better to talk directly in these terms because of (1) (see above).

by FabHK 8y ago

thaumasiotes 8y ago

So, electrons are attracted to protons by the electromagnetic force, but they don't make it all the way there because they are repelled by some other force. You don't have a paradox because our model of the electromagnetic force doesn't specify that it's the only force there is. But if a negative mass is moving towards you and encounters a repulsive force, that repulsive force will, by definition, move the negative mass further toward you. It would need to encounter an attractive force to reach equilibrium. Note that, unlike in the electron example, it doesn't matter what kind of force is being applied; the object's negative mass tells us that the response to any repulsive force is acceleration towards the force.

millstone 8y ago
> they don't make it all the way there because they are repelled by some other force A repulsive force is not the best way to think about it. The potential of the nucleus is the usual -1/r, and goes to (negative) infinity at zero. A repulsive force would be incorporated into the potential and appear as a bump around the nucleus, and would mess up the electron orbital. A hand-wavy explanation of why the electron doesn't fall in: if you try to push the electrons into the nucleus, you necessarily localize the electron into a smaller volume; this means its wavefunction must get "spikier" and therefore it has more kinetic energy. This kinetic energy rises faster than the potential energy drops, so the state of lowest energy is actually found at an average radius > 0. Note that it took quantum mechanics to rescue the atom. A classical electron could fall into the nucleus. I do not see any problem with a negative-mass particle accelerating towards the force. The analogy with opposite charges seems right to me.
- btilly 8y ago
  A different hand-wavy explanation. The places that an electron can be found are described by a wave pattern. If the electron is staying in place around a nucleus, that wave pattern has to be a standing wave that reinforces itself. To reinforce itself it has to wrap around the nucleus an integer number of times. This explanation doesn't just explain why it doesn't fall in, it also explains why there are discrete shells that it could be found in, corresponding to how many times it wraps around the nucleus. (It doesn't explain why only a finite number can fit in each shell though. Or why bigger shells can have more electron orbitals. Or...well the actual theory has to be good for something!)
  - drjesusphd 8y ago
    This is the Bohr model of the atom, but was replaced by a proper quantum theory.
    - btilly 8y ago
      Yes. Which is why I called it "a different handwavy theory". And also listed some of the things that it didn't explain.
  - thaumasiotes 8y ago
    I'm not really interested (here) in the reality of the interaction between the electron and the nucleus. I don't think the existence of an electromagnetic field is a good argument against its own existence as argued by FabHK further up. I also don't think FabHK's argument works as an analogy to my problem with negative mass. The electromagnetic field is not self-reinforcing in the same way. Imagine that you're holding a marble of negative glass in your fist. Negative glass is indistinguishable from ordinary glass except that its mass is negative rather than positive. As we all know, the first step in solving any physics problem is to draw a free-body diagram. ( http://www.smbc-comics.com/comics/20130616.png http://www.smbc-comics.com/comics/20130616.png ) Let's draw one here. First, we'll do one for an ordinary marble: 1. The enormous mass of the earth attracts the marble downward proportionately to the marble's mass. 2. The marble cannot accelerate downward, because it's stuck in your fist. Your fist experiences a downward force equal to the weight of the marble. 3. By Newton's third law, your fist exerts an upward force on the marble equal to the force exerted by the marble on your fist. This is exactly equal to the weight of the marble, but in the opposite direction. The two forces cancel, and the marble is at rest. Now for the negative marble: 1. The enormous mass of the earth attracts the marble downward proportionately to the marble's mass. Because that mass is negative, the marble attempts to accelerate upward. 2. The marble can't accelerate upward, because it's stuck in your fist. Your fist experiences an upward force equal to the weight of the marble. 3. By Newton's third law, your fist exerts an downward force on the marble equal to the force exerted by the marble on your fist. This is exactly equal to the weight of the marble, and in the same direction, effectively doubling the marble's weight. The marble is now trying twice as hard to accelerate upward into your fist. 2. (Again.) The marble can't accelerate upward, because it's stuck in your fist. Your fist experiences an upward force equal to double the weight of the marble. Nothing has moved; we're still just trying to work out the balance of forces within the system at rest. 3. (Again.) You can see where this is going. What is the conceptual breakthrough that rescues negative mass from this trap? (Note that saying the marble has negative inertial and gravitational mass, as opposed to negative inertial mass and positive gravitational mass, doesn't help: the marble will be trying to accelerate downward instead of upward, but it will still be doing it with infinite force.)
vesinisa 8y ago
> But if a negative mass is moving towards you and encounters a repulsive force, that repulsive force will, by definition, move the negative mass further toward you I am not sure you understand what "repulse" means.. Joking aside, it's easy enough to imagine negative gravity. Do you mean that such counter intuitive behavior would be the natural consequence of negative inertial mass?
infinity0 8y ago
> that repulsive force will, by definition, move the negative mass further toward you. only if the repulsive force is negative gravity. If a positive-mass electron attracts a negative-mass electron, the repulsive electromagnetic force will still keep them from making it all the way there.
- thaumasiotes 8y ago
  >> that repulsive force will, by definition, move the negative mass further toward you. > only if the repulsive force is negative gravity We're talking about negative inertial mass, not negative gravitational mass. Negative inertial mass means accelerating against the direction of any force applied to you, including but not limited to gravity.

deytempo 8y ago

The problem with these papers is there is no compilers to perfectly test the logic except peer review so no one knows if its horse shit or not until someone comes along and comes up with some way to prove it wrong, so I would not be so quick to say “if that’s an obvious contradiction, the author would have caught it”

phs318u 8y ago
Physics is highly mathematical and as such, can indeed be "tested" (i.e. proven) to be consistent with mathematical laws. This is fairly straightforward (for suitably mathematically literate people). The real issues are: 1. can the theory make testable predictions that can be verified by observation? e.g. string theory has had issues with this. 2. what does <wierd-mathematical-construct> "mean"? e.g. negative mass, spooky action at a distance, spacetime singularity. In practice, only 1 really matters. However, 2 tends to bug a lot of people (consider the arguments around what the quantum world really represents). I'm one for whom 2 is important. "But what does it really mean?" Back to your original point, looking at the paper [0], it doesn't seem too ridiculously hard to validate the math for someone familiar with this space (see what I did there?), unlike me who has forgotten everything I was taught [1]. [0] https://arxiv.org/pdf/1712.07962.pdf https://arxiv.org/pdf/1712.07962.pdf [1] I have a physics degree but that was 33 years ago and I've been doing nothing but IT since.
- v_lisivka 8y ago
  1. OpenGL makes good predictions. Why not to switch to OpenGL terms when talking about physics?
  - Retra 8y ago
    Because physicists would find it totally unsuitable for their requirements?
    - v_lisivka 8y ago
      Why match is better for that? To compute prediction, you will need to use computer and compiler, so it better to talk directly in these terms because of (1) (see above).