6 ms·

Can someone who knows more physics than I tell me if the question is even meaningful? My naive assumption is that we'd have as many dimensions as there are dist

Can someone who knows more physics than I tell me if the question is even meaningful? My naive assumption is that we'd have as many dimensions as there are distinct things (atoms, I suppose).

Borrible 6y ago
That implies there ARE distinct things, doesn't it?
- uniqueid 6y ago
  'Distinct in some context', I guess. Eg: a person could take a photograph of clouds in the sky and come up with list of rules to categorize them into a number of discrete clouds.
  - Borrible 6y ago
    Don't take my comment too seriously, although it is based on serious speculation and thought. I only wanted to refer on the one hand to the philosophical or at least linguistic problem, what a 'thing' is and the possibility of the unification to one field of the, up to now still multiform, thing in the quantum field theory we call Universe. Just a mind game. Or not... ;-) What is meant in the article is that one needs currently 11 coordinates in a mathematical space which is supposed to be a mapping of our physical reality to describe a point in it.
    - deleted 6y ago
      [deleted]
- jpeanuts 6y ago
  Not at all serious but... maybe all electrons have the same mass, charge, etc. because there is only one electron, bouncing backwards and forwards through time. As it passes backwards we see it as the anti-electron (positron). When they meet they annihilate from our perspective, but that's just the electron being reflected and becoming a positron heading backwards. To be clear this is all not at all consistent with observations - just a fun(?) thought experiment.
  - Borrible 6y ago
    https://en.m.wikipedia.org/wiki/One-electron_universe https://en.m.wikipedia.org/wiki/One-electron_universe
  - jstanley 6y ago
    Out of interest, what observations is this not consistent with?
    - magicalhippo 6y ago
      The argument against is summarized in the Wikipedia article. Basically it is this: We measure electrons in different places all the time. Due to the speed of light it can't instantly move from A to B, so for this to actually be one electron it would have to travel back in time to be at some place at the right time. However, an electron traveling back in time would appear as a positron, so if that what was going on we should be seeing a fairly equal number of positrons as we do electrons, as the one electron rushes around to appear as an electron where it needs to. Except we don't, electrons outnumber positrons by a huge margin.
      - bostonpete 6y ago
        > However, an electron traveling back in time would appear as a positron, so if that what was going on we should be seeing a fairly equal number of positrons as we do electrons, as the one electron rushes around to appear as an electron where it needs to. What about this part of the article though...? "According to Feynman he raised this issue with Wheeler, who speculated that the missing positrons might be hidden within protons."
        magicalhippo 6y ago
        As noted, the discussion between Wheeler and Feynman was in 1940, long before the development of the Standard Model[1]. In the Standard Model there is a sea of virtual particles in the nucleus, but they're virtual and hence not real in the sense that the positron in the One Electron model would have to be. At least that's my understanding. Also, electrons can travel over large distances, CRT monitors do that all the time for example. So I'm not entirely sure how Wheeler imagined hiding the positrons in the nucleus would solve the whole positron problem. [1]: https://en.wikipedia.org/wiki/Quark#History https://en.wikipedia.org/wiki/Quark#History
- SubiculumCode 6y ago
  are you saying: what if dimensions are not discrete, but fields.?
  - Borrible 6y ago
    Ah, no no no. Oh, God, what have I done!? What I wanted to indicate was firstly, as a physical speculation the possibility of a universal field in the sense of the quantum field theory, which shows additional dimensionality with breaking of its symmetry in hierarchical levels and thus there is in a certain sense only one thing, the universal field. Secondly, the question when something is considered as an independent 'thing', which is a philosophical question. Third, the question of the interpretation of the relation of mathematical apparatus and reality. What does the dimensionality of the mathematical model mean? A scientific-theoretical question. And the gluons of this all are just linguistics and semantics. ;-)))
compressedgas 6y ago
That is what is called by the name of degrees of freedom. The dimensions of space-time are to the degrees of freedom as the basis vectors of a coordinate system are to the homogeneous matrix. Or something like that.
ithkuil 6y ago
Perhaps what you mean is the dimensionality of hilbert space
monkeycantype 6y ago
Do I know more physics than you? Problynot. But he’s my attempt to explain how I understood the article: We experience a universe with 3 spatial dimensions, if we imagine an axis through space, there are two other axes orthogonal to the first axis and to each other, that an object can move on any of the axes independently, without moving in any of the others. We can’t add a fourth axis, there is no fourth line we can choose along which an object can move without also moving in at least one other dimension - or at least that is our experience. We also know from seeing 2d shadows of 3D objects, that a higher dimensional object can be projected into lower dimensions. We can twist an object and see changes in a shadow that make perfect sense if we know the shadow is a 2d projection of a rotating 3D object. There are features of our universe that make sense if we think about the universe as a 3D shadow of a higher dimension system. So what does that mean? Are higher dimensional models a nice math trick, or do the models work because they describe the true higher dimensional nature of the universe, that we experience as a lower dimensional projection. Ok time to pass the baton who can take this deeper.
- lgl 6y ago
  Good answer, a 4th dimension and the shadow projection analogy is brilliantly exemplified by Carl Sagan in this popular video: https://www.youtube.com/watch?v=UnURElCzGc0 https://www.youtube.com/watch?v=UnURElCzGc0
  - travisjungroth 6y ago
    I think it's also the most important analogy, more than things like a 2D being meeting a 3D being. The goal of these physics models is to better explain the world. It's a hint that a model is better when it simplifies things (not that the model itself is necessarily simple). Think of the crazy things astronomers drew to explain the paths of the planets in the sky with the Earth in the center and circular orbits. But what if the Sun is in the center and the orbits are ellipses? Things are way easier. Same thing happens if you look at the projection of a cube. It looks like chaos. But if you are aware of a third dimension, it all makes a lot of sense.
- m12k 6y ago
toolslive 6y ago
You don't need to know more physics. If you see something (a particle fe) disappear, and reappear somewhere else then a possible explanation is that it got there via another dimension. So if you eliminate all other possible explanations, the only remaining one is that there must be more dimensions. However, since things appearing and disappearing does not happen on macroscopic scale, the dimensions must be small.
- gtt 6y ago
  So this is how UFOs move!
bArray 6y ago
> Can someone who knows more physics than I tell me if the question is even meaningful? Any new physical property could potentially be exploited to improve some existing idea. The discovery of the electromagnetic force eventually gave way to WiFi and 5G. The discovery of the quantum realm for example has yielded the concept of quantum computing. If we can discover high dimensions, we can eventually interact with them and use them.
wombat23 6y ago
In this context, the dimensions are the degrees of freedom that a particle can move in. I think it becomes meaningful when you consider the metric (ie. definition of distances) and the laws of nature inside that space, and if additional dimensions help in formulating more phenomena with a less complex system of equations. -> Classically, there are 3 spatial dimensions (directions of movement) with Euclidean metric, and all the classical laws (Newton's laws, gravity, etc.). Quite successful, but breaking down in extreme cases (high energy, ie. velocity/mass/etc). +there is a whole range of seemingly unrelated laws necessary. -> with relativity theory (both special and general), time becomes a 4th dimension, but it has a special status in the metric (opposed sign), making spacetime non-Euclidean. One effect of this is suddenly you don't need a law of gravity anymore. Things just follow geodesics in this space. It also explains some effects that could not be derived from classical gravity. Essentially explaining more phenomena with less "overhead", in exchange for more dimensions.

Can someone who knows more physics than I tell me if the question is even meaningful? My naive assumption is that we'd have as many dimensions as there are distinct things (atoms, I suppose).

Borrible 6y ago

That implies there ARE distinct things, doesn't it?

uniqueid 6y ago
'Distinct in some context', I guess. Eg: a person could take a photograph of clouds in the sky and come up with list of rules to categorize them into a number of discrete clouds.
- Borrible 6y ago
  Don't take my comment too seriously, although it is based on serious speculation and thought. I only wanted to refer on the one hand to the philosophical or at least linguistic problem, what a 'thing' is and the possibility of the unification to one field of the, up to now still multiform, thing in the quantum field theory we call Universe. Just a mind game. Or not... ;-) What is meant in the article is that one needs currently 11 coordinates in a mathematical space which is supposed to be a mapping of our physical reality to describe a point in it.
  - deleted 6y ago
    [deleted]
jpeanuts 6y ago
Not at all serious but... maybe all electrons have the same mass, charge, etc. because there is only one electron, bouncing backwards and forwards through time. As it passes backwards we see it as the anti-electron (positron). When they meet they annihilate from our perspective, but that's just the electron being reflected and becoming a positron heading backwards. To be clear this is all not at all consistent with observations - just a fun(?) thought experiment.
- Borrible 6y ago
  https://en.m.wikipedia.org/wiki/One-electron_universe https://en.m.wikipedia.org/wiki/One-electron_universe
- jstanley 6y ago
  Out of interest, what observations is this not consistent with?
  - magicalhippo 6y ago
    The argument against is summarized in the Wikipedia article. Basically it is this: We measure electrons in different places all the time. Due to the speed of light it can't instantly move from A to B, so for this to actually be one electron it would have to travel back in time to be at some place at the right time. However, an electron traveling back in time would appear as a positron, so if that what was going on we should be seeing a fairly equal number of positrons as we do electrons, as the one electron rushes around to appear as an electron where it needs to. Except we don't, electrons outnumber positrons by a huge margin.
    - bostonpete 6y ago
      > However, an electron traveling back in time would appear as a positron, so if that what was going on we should be seeing a fairly equal number of positrons as we do electrons, as the one electron rushes around to appear as an electron where it needs to. What about this part of the article though...? "According to Feynman he raised this issue with Wheeler, who speculated that the missing positrons might be hidden within protons."
      - magicalhippo 6y ago
        As noted, the discussion between Wheeler and Feynman was in 1940, long before the development of the Standard Model[1]. In the Standard Model there is a sea of virtual particles in the nucleus, but they're virtual and hence not real in the sense that the positron in the One Electron model would have to be. At least that's my understanding. Also, electrons can travel over large distances, CRT monitors do that all the time for example. So I'm not entirely sure how Wheeler imagined hiding the positrons in the nucleus would solve the whole positron problem. [1]: https://en.wikipedia.org/wiki/Quark#History https://en.wikipedia.org/wiki/Quark#History
SubiculumCode 6y ago
are you saying: what if dimensions are not discrete, but fields.?
- Borrible 6y ago
  Ah, no no no. Oh, God, what have I done!? What I wanted to indicate was firstly, as a physical speculation the possibility of a universal field in the sense of the quantum field theory, which shows additional dimensionality with breaking of its symmetry in hierarchical levels and thus there is in a certain sense only one thing, the universal field. Secondly, the question when something is considered as an independent 'thing', which is a philosophical question. Third, the question of the interpretation of the relation of mathematical apparatus and reality. What does the dimensionality of the mathematical model mean? A scientific-theoretical question. And the gluons of this all are just linguistics and semantics. ;-)))

compressedgas 6y ago

That is what is called by the name of degrees of freedom. The dimensions of space-time are to the degrees of freedom as the basis vectors of a coordinate system are to the homogeneous matrix. Or something like that.

ithkuil 6y ago

Perhaps what you mean is the dimensionality of hilbert space

monkeycantype 6y ago

Do I know more physics than you? Problynot. But he’s my attempt to explain how I understood the article: We experience a universe with 3 spatial dimensions, if we imagine an axis through space, there are two other axes orthogonal to the first axis and to each other, that an object can move on any of the axes independently, without moving in any of the others. We can’t add a fourth axis, there is no fourth line we can choose along which an object can move without also moving in at least one other dimension - or at least that is our experience. We also know from seeing 2d shadows of 3D objects, that a higher dimensional object can be projected into lower dimensions. We can twist an object and see changes in a shadow that make perfect sense if we know the shadow is a 2d projection of a rotating 3D object. There are features of our universe that make sense if we think about the universe as a 3D shadow of a higher dimension system. So what does that mean? Are higher dimensional models a nice math trick, or do the models work because they describe the true higher dimensional nature of the universe, that we experience as a lower dimensional projection. Ok time to pass the baton who can take this deeper.

lgl 6y ago
Good answer, a 4th dimension and the shadow projection analogy is brilliantly exemplified by Carl Sagan in this popular video: https://www.youtube.com/watch?v=UnURElCzGc0 https://www.youtube.com/watch?v=UnURElCzGc0
- travisjungroth 6y ago
  I think it's also the most important analogy, more than things like a 2D being meeting a 3D being. The goal of these physics models is to better explain the world. It's a hint that a model is better when it simplifies things (not that the model itself is necessarily simple). Think of the crazy things astronomers drew to explain the paths of the planets in the sky with the Earth in the center and circular orbits. But what if the Sun is in the center and the orbits are ellipses? Things are way easier. Same thing happens if you look at the projection of a cube. It looks like chaos. But if you are aware of a third dimension, it all makes a lot of sense.
m12k 6y ago

toolslive 6y ago

You don't need to know more physics. If you see something (a particle fe) disappear, and reappear somewhere else then a possible explanation is that it got there via another dimension. So if you eliminate all other possible explanations, the only remaining one is that there must be more dimensions. However, since things appearing and disappearing does not happen on macroscopic scale, the dimensions must be small.

gtt 6y ago
So this is how UFOs move!

bArray 6y ago

> Can someone who knows more physics than I tell me if the question is even meaningful? Any new physical property could potentially be exploited to improve some existing idea. The discovery of the electromagnetic force eventually gave way to WiFi and 5G. The discovery of the quantum realm for example has yielded the concept of quantum computing. If we can discover high dimensions, we can eventually interact with them and use them.

wombat23 6y ago

In this context, the dimensions are the degrees of freedom that a particle can move in. I think it becomes meaningful when you consider the metric (ie. definition of distances) and the laws of nature inside that space, and if additional dimensions help in formulating more phenomena with a less complex system of equations. -> Classically, there are 3 spatial dimensions (directions of movement) with Euclidean metric, and all the classical laws (Newton's laws, gravity, etc.). Quite successful, but breaking down in extreme cases (high energy, ie. velocity/mass/etc). +there is a whole range of seemingly unrelated laws necessary. -> with relativity theory (both special and general), time becomes a 4th dimension, but it has a special status in the metric (opposed sign), making spacetime non-Euclidean. One effect of this is suddenly you don't need a law of gravity anymore. Things just follow geodesics in this space. It also explains some effects that could not be derived from classical gravity. Essentially explaining more phenomena with less "overhead", in exchange for more dimensions.