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If they are going to use up to 26 dimensions in their theories, of what use is a machine that only senses the 4 dimensions we normally perceive? Maybe all thes

If they are going to use up to 26 dimensions in their theories, of what use is a machine that only senses the 4 dimensions we normally perceive? Maybe all these missing particles are in some of the other 22? I'm sorry, but I don't think solid answers to some of the big questions are ever going to be found using these experiments. I also question whether thinking in terms of particles is even the right paradigm. We may be just attempting to mold observations into our own incorrect model.

pavel_lishin 8y ago
If we live in a world of three spatial dimensions, plus one of time, what use is a camera that only captures a two-dimensional image?
snowwrestler 8y ago
It's fun to speculate, but it's worth pointing out that science progresses via actual work. If you know how to build a machine that senses more than 4 dimensions, please build it and run some experiments! If you can't, then recognize the limitations of critique. Anyone can sit back and say "hey, what if we're doing things wrong?" Scientists already spend most of their time in this area of thinking. The operative question isn't "what use are our limited experiments?" Scientists know their experiments are limited. The real question is, "how, specifically, can we do new experiments?" Or for theoreticians, it's not "is our model incorrect?" Scientists know the theories aren't correct... not totally correct, anyway. The real question for a theoretician is, "what new model can I propose that matches all known evidence, and also opens the door for new understanding?"
- XalvinX 8y ago
  I guess I was just thinking out loud, but then I did read the article and have read many other like it over the last 30+ years. I can see it must be fun to speculate, but also seemingly profitable for some of these guys too, eh? I wonder how much a "theoretical physicist" gets paid, anyways?
theoh 8y ago
It doesn't work like that ("in some of the other 22"). One crude way to think about it is that particle has a location in each dimension. In other words, position is a vector whether in 3D or 26D or whatever. It's not possible to be "in other dimensions" any more than a normal point in Cartesian space can lack an X coordinate. The popular sci-fi idea that other dimensions constitute an "elsewhere", e.g. dimensions or "planes" outside our reality, is not what is meant when particle physicists talk about 26D space.
- BalinKing 8y ago
  This is what I’ve always assumed, but then I’ve heard from more than one place that some of string theory’s 26 dimensions are too small to observe, or are in between other dimensions, or other (seemingly) weird stuff like that. I obviously don’t know too much myself about physics :-), but do you know what that means?
  - theoh 8y ago
    The smallness issue is pretty straightforward. https://en.wikipedia.org/wiki/Compactification_(physics) https://en.wikipedia.org/wiki/Compactification_(physics) Assuming that the universe is closed like the surface of a sphere, heading off in any direction will eventually bring you back to where you started. Compactified dimensions are roughly like directions in which, for example, that trip is very much shorter, maybe too short to observe. It gets complicated and I'm not a physicist, but the idea that the size of the universe is different on different dimensions is the key one. As far as in-between dimensions goes, I don't know. Maybe it was a reference to fractal dimension.
  - raattgift 8y ago
    Here's a bit about Kaluza-Klein extra dimensions, as one finds in string theory. K-K theory started with just one extra dimension in an effort to unify gravitation and electromagnetism. https://plus.maths.org/content/10-dimensions-and-more-string-theory https://plus.maths.org/content/10-dimensions-and-more-string... I'll try to generalize and simplify a bit: There are other types of theory with extra spacetime dimensions, too. A physical interpretation (for many of them, anyway) about why we don't see the extra dimensions is that we can't move in them at all, or only very very little. Consider what you're doing right now, sitting in place at your computer. In a standard 3-coordinate system of your room, with the origin of Cartesian coordinates (x,y,z) = (0,0,0) the floor beneath the centre of your chair, and measuring distances in light-nanoseconds, your centre of mass is a couple light nanoseconds in the z direction, so let's label that (0,0,3). We can extend from Cartesian (spatial) 3-coordinates to Minkowskian (spacetime) 4-coordinates by extending (x,y,z) to (x,y,z,t). In that case, we might decide your centre of mass right now compared to an extension of our previous origin is (0,0,3,3 * 10^10), where we measure t in nanoseconds rather than light-nanoseconds[1]. If there is a fifth coordinate, and it's spacelike, we'd measure in light-nanoseconds and then you're now at (0,0,3,4 * 10^10,0), because you're still not moving in space, only in time. If you were to raise or lower your chair, z would increase or decrease respectively, t would continue to tick along in nanoseconds, and all the other dimensions would remain 0. Likewise, if you slide your chair to the right, you'd increase the x dimension so now you could be (3,0,3,6 * 10^10,0). You can keep moving arbitrarily within this local system of coordinates, and try as hard as you like, you would not be able to go backwards in the time coordinate, and you would not be able to move in either direction in the extra spacelike dimension. In theories that import extra spacelike dimension theories typically allow for extremely small movements through them, usually as a small oscillation, say (using nano light seconds still) 0->10^-35->0. That's so small you won't notice, and it usually happens across a tiny interval along the timelike dimension (e.g., you're only nonzero for a tiny fraction of a nanosecond). Moreover, even such a small oscillation is only allowed under extreme (usually high) energy conditions. Kaluza-Klein's original theory represented this sort of minor deviation from zero as a loop with a circumference on the order of 10^-33 cm, compared to the line-like (uncurled/unlooped) other axes which extend in principle to infinity. [2] There's the opposite form of inaccessibility, where everything in the universe that we can observe propagates identically along the extra dimension as everything else, so for example you can't see the difference in the "w" dimension between you and Voyager 2, even though you can certainly see differences in the other four dimensions. [3] For an example of how this could be useful, one can write down a theory that in such a background a very weakly-interacting particle (like a graviton or a neutrino-like particle) might propagate differently from everything else. Finally, from various precision tests of inverse square laws, and careful observation of the orbits of various massive bodies at many different mass scales, we can make some pretty strong bounds on how accessible small and large dimensions are. They're basically inaccessible to humans at present level of technology. Consequently, it is still entirely sufficient to use 3 spatial and 1 timelike dimensions, and safest to assume (thanks to the weight of a lot of evidence) that that's all there is. If high energy particle physics or the study of extreme gravitational physics provides evidence that 3+1 is insufficient, that'll be really cool for theoreticians. But that's a huuuuuge if. - -- [1] ignoring issues of sign [2] this assumes a flat spacetime highly similar to Special Relativity; importantly KK theory deliberately breaks that similarity, but this conceptual comparison of the shape of the five axes will have to do unless I can think of some better way of putting it non-mathematically [3] ignoring general relativistic effects
TheOtherHobbes 8y ago
For some reason it's very hard to build 26-dimensional machines in a 4-dimensional universe.
- gus_massa 8y ago
  [If the theory is true ...] The machine has 26 dimensions because this is a 26 dimensional machine. The difference is that in 3 dimensions the size is about a few inches, in the "time" dimension the size is a few years and in the other dimensions are very very small (I don't remember the actual guess, because nobody is sure, ¿10E-100inches?) So for everyday calculations you can use the 3+1 dimensions and ignore the others. For calculations about the effects in tiny elementary particles the other dimensions are important. Imagine that you are living in the surface of a long garden hose. Is it a 1 dimensional word or a 2 dimensional word?
  - XalvinX 8y ago
    Yeah, but is an "inch" even a thing in dimension #18? And this smallness aspect wouldn't disprove what I originally theorized here anyways...these subatomic particle are fucking small as shit, aren't they?????? lol....sorry
    - gus_massa 8y ago
      [If the theory is true ...] > Yeah, but is an "inch" even a thing in dimension #18? Yes. The idea is that locally the "distance" called "s" is -s² = -c²t² + x² + y² + z² + w² + v² + ... + q² where w, v, ..., q are the other coordinates, this are not the official names, I just made up some names because it's difficult to use subscripts. This is only local, because if you move an inch in the "w" direction you will wrap many many many times, so the distance is more complicated (like the complicate calculation to transform latitude and longitude into the distance you must walk over the Earth surface). So an inch in "w" is something clear, but moving an inch in "w" will not take you very far away, because the universe is wrapped and you will only make a gazillion of turns like in a carousel. > And this smallness aspect wouldn't disprove what I originally theorized here anyways...these subatomic particle are fucking small as shit, aren't they?????? lol....sorry The particles are punctual, the size is "0". The problem is that you can't keep them perfectly aligned in the hyperplane where w=0, v=0, ..., q=0. When you build a machine, you somewhat fix the position of the particles in x, y and z, but you have no control of the position in w, v, ..., q. So the machine is in the location 0<x<1, 0<y<1, 0<z<1, w=whatever, v=whatever, ..., q=whatever. [In string theory, the size is not 0 because the particles are part of a tiny string that has a tiny but not 0 size. So wait a few decades/centuries until we are sure.]

pavel_lishin 8y ago

If we live in a world of three spatial dimensions, plus one of time, what use is a camera that only captures a two-dimensional image?

snowwrestler 8y ago

It's fun to speculate, but it's worth pointing out that science progresses via actual work. If you know how to build a machine that senses more than 4 dimensions, please build it and run some experiments! If you can't, then recognize the limitations of critique. Anyone can sit back and say "hey, what if we're doing things wrong?" Scientists already spend most of their time in this area of thinking. The operative question isn't "what use are our limited experiments?" Scientists know their experiments are limited. The real question is, "how, specifically, can we do new experiments?" Or for theoreticians, it's not "is our model incorrect?" Scientists know the theories aren't correct... not totally correct, anyway. The real question for a theoretician is, "what new model can I propose that matches all known evidence, and also opens the door for new understanding?"

XalvinX 8y ago
I guess I was just thinking out loud, but then I did read the article and have read many other like it over the last 30+ years. I can see it must be fun to speculate, but also seemingly profitable for some of these guys too, eh? I wonder how much a "theoretical physicist" gets paid, anyways?

theoh 8y ago

It doesn't work like that ("in some of the other 22"). One crude way to think about it is that particle has a location in each dimension. In other words, position is a vector whether in 3D or 26D or whatever. It's not possible to be "in other dimensions" any more than a normal point in Cartesian space can lack an X coordinate. The popular sci-fi idea that other dimensions constitute an "elsewhere", e.g. dimensions or "planes" outside our reality, is not what is meant when particle physicists talk about 26D space.

BalinKing 8y ago
This is what I’ve always assumed, but then I’ve heard from more than one place that some of string theory’s 26 dimensions are too small to observe, or are in between other dimensions, or other (seemingly) weird stuff like that. I obviously don’t know too much myself about physics :-), but do you know what that means?
- theoh 8y ago
  The smallness issue is pretty straightforward. https://en.wikipedia.org/wiki/Compactification_(physics) https://en.wikipedia.org/wiki/Compactification_(physics) Assuming that the universe is closed like the surface of a sphere, heading off in any direction will eventually bring you back to where you started. Compactified dimensions are roughly like directions in which, for example, that trip is very much shorter, maybe too short to observe. It gets complicated and I'm not a physicist, but the idea that the size of the universe is different on different dimensions is the key one. As far as in-between dimensions goes, I don't know. Maybe it was a reference to fractal dimension.
- raattgift 8y ago
  Here's a bit about Kaluza-Klein extra dimensions, as one finds in string theory. K-K theory started with just one extra dimension in an effort to unify gravitation and electromagnetism. https://plus.maths.org/content/10-dimensions-and-more-string-theory https://plus.maths.org/content/10-dimensions-and-more-string... I'll try to generalize and simplify a bit: There are other types of theory with extra spacetime dimensions, too. A physical interpretation (for many of them, anyway) about why we don't see the extra dimensions is that we can't move in them at all, or only very very little. Consider what you're doing right now, sitting in place at your computer. In a standard 3-coordinate system of your room, with the origin of Cartesian coordinates (x,y,z) = (0,0,0) the floor beneath the centre of your chair, and measuring distances in light-nanoseconds, your centre of mass is a couple light nanoseconds in the z direction, so let's label that (0,0,3). We can extend from Cartesian (spatial) 3-coordinates to Minkowskian (spacetime) 4-coordinates by extending (x,y,z) to (x,y,z,t). In that case, we might decide your centre of mass right now compared to an extension of our previous origin is (0,0,3,3 * 10^10), where we measure t in nanoseconds rather than light-nanoseconds[1]. If there is a fifth coordinate, and it's spacelike, we'd measure in light-nanoseconds and then you're now at (0,0,3,4 * 10^10,0), because you're still not moving in space, only in time. If you were to raise or lower your chair, z would increase or decrease respectively, t would continue to tick along in nanoseconds, and all the other dimensions would remain 0. Likewise, if you slide your chair to the right, you'd increase the x dimension so now you could be (3,0,3,6 * 10^10,0). You can keep moving arbitrarily within this local system of coordinates, and try as hard as you like, you would not be able to go backwards in the time coordinate, and you would not be able to move in either direction in the extra spacelike dimension. In theories that import extra spacelike dimension theories typically allow for extremely small movements through them, usually as a small oscillation, say (using nano light seconds still) 0->10^-35->0. That's so small you won't notice, and it usually happens across a tiny interval along the timelike dimension (e.g., you're only nonzero for a tiny fraction of a nanosecond). Moreover, even such a small oscillation is only allowed under extreme (usually high) energy conditions. Kaluza-Klein's original theory represented this sort of minor deviation from zero as a loop with a circumference on the order of 10^-33 cm, compared to the line-like (uncurled/unlooped) other axes which extend in principle to infinity. [2] There's the opposite form of inaccessibility, where everything in the universe that we can observe propagates identically along the extra dimension as everything else, so for example you can't see the difference in the "w" dimension between you and Voyager 2, even though you can certainly see differences in the other four dimensions. [3] For an example of how this could be useful, one can write down a theory that in such a background a very weakly-interacting particle (like a graviton or a neutrino-like particle) might propagate differently from everything else. Finally, from various precision tests of inverse square laws, and careful observation of the orbits of various massive bodies at many different mass scales, we can make some pretty strong bounds on how accessible small and large dimensions are. They're basically inaccessible to humans at present level of technology. Consequently, it is still entirely sufficient to use 3 spatial and 1 timelike dimensions, and safest to assume (thanks to the weight of a lot of evidence) that that's all there is. If high energy particle physics or the study of extreme gravitational physics provides evidence that 3+1 is insufficient, that'll be really cool for theoreticians. But that's a huuuuuge if. - -- [1] ignoring issues of sign [2] this assumes a flat spacetime highly similar to Special Relativity; importantly KK theory deliberately breaks that similarity, but this conceptual comparison of the shape of the five axes will have to do unless I can think of some better way of putting it non-mathematically [3] ignoring general relativistic effects

TheOtherHobbes 8y ago

For some reason it's very hard to build 26-dimensional machines in a 4-dimensional universe.

gus_massa 8y ago
[If the theory is true ...] The machine has 26 dimensions because this is a 26 dimensional machine. The difference is that in 3 dimensions the size is about a few inches, in the "time" dimension the size is a few years and in the other dimensions are very very small (I don't remember the actual guess, because nobody is sure, ¿10E-100inches?) So for everyday calculations you can use the 3+1 dimensions and ignore the others. For calculations about the effects in tiny elementary particles the other dimensions are important. Imagine that you are living in the surface of a long garden hose. Is it a 1 dimensional word or a 2 dimensional word?
- XalvinX 8y ago
  Yeah, but is an "inch" even a thing in dimension #18? And this smallness aspect wouldn't disprove what I originally theorized here anyways...these subatomic particle are fucking small as shit, aren't they?????? lol....sorry
  - gus_massa 8y ago
    [If the theory is true ...] > Yeah, but is an "inch" even a thing in dimension #18? Yes. The idea is that locally the "distance" called "s" is -s² = -c²t² + x² + y² + z² + w² + v² + ... + q² where w, v, ..., q are the other coordinates, this are not the official names, I just made up some names because it's difficult to use subscripts. This is only local, because if you move an inch in the "w" direction you will wrap many many many times, so the distance is more complicated (like the complicate calculation to transform latitude and longitude into the distance you must walk over the Earth surface). So an inch in "w" is something clear, but moving an inch in "w" will not take you very far away, because the universe is wrapped and you will only make a gazillion of turns like in a carousel. > And this smallness aspect wouldn't disprove what I originally theorized here anyways...these subatomic particle are fucking small as shit, aren't they?????? lol....sorry The particles are punctual, the size is "0". The problem is that you can't keep them perfectly aligned in the hyperplane where w=0, v=0, ..., q=0. When you build a machine, you somewhat fix the position of the particles in x, y and z, but you have no control of the position in w, v, ..., q. So the machine is in the location 0<x<1, 0<y<1, 0<z<1, w=whatever, v=whatever, ..., q=whatever. [In string theory, the size is not 0 because the particles are part of a tiny string that has a tiny but not 0 size. So wait a few decades/centuries until we are sure.]