7 ms·

A Magnetic Wormhole (2015)

106 points by jotux 10y ago

wyager 10y ago
The interesting part of wormholes is that they introduce topologies that connect two extrinsically "distant" points, yes? This research doesn't appear to do that; it seems like it just "hides" the magnetic field for a distance. The field still moves slower than light.
- ars 10y ago
  The other interesting thing about wormholes is they don't exist, and can't exist without basically rewriting every law of physics we have. They violate almost every conservation law there is. They are a mathematical curiosity, not a thing that could actually exist. If you could rewrite the laws of physics there are lots of cool things you could do, wormholes would just be the start......
  - derefr 10y ago
    It's the creation of wormholes that would violate physics, though, right? AFAIK our current model of physics would work just fine to describe a universe that came into existence with permanent, stable wormholes already in it; that'd just be part of its topology.
    - throw98172 10y ago
      Even an existing wormhole could still cause problems. Consider for example a wormhole between two points with different gravitational potential — say one end is close to the Earth and the other end is further away. Then if you could let yourself fall from the higher to the lower point, and took the wormhole to complete a loop, you would end the loop with more energy than you started with, which is a big no-no!
    - mahranch 10y ago
      He has it backwards. Our current physics allow for wormholes. They probably don't exist but if they were literally impossible, then we would need to rewrite our current physics. Wormholes are more than likely impossible because to hold one open for travel, you would need some sort of negative matter/negative energy. That isn't forbidden by physics, but it's unlikely that it exists since we haven't seen any. Without negative energy/matter to hold a wormhole open, even if you could create one, just a single proton or electron would cause the wormhole to become unstable and collapse in on itself, and doing so faster than the proton could travel through.
      - ars 10y ago
        > Our current physics allow for wormholes. No, it does not. See my more detailed reply here: https://news.ycombinator.com/item?id=12301781 https://news.ycombinator.com/item?id=12301781
    - ars 10y ago
      No. Using them is the problem. Say you are in a gravity well with one side of the wormhole, and the other side is outside the well. You could "lift" matter outside the gravity well without spending energy. There are other problems as well: Gravity has no discontinuities, as objects move, the gravitational field moves with it. You never have a situation where gravity just suddenly shows up. (The same is true for an electrical field BTW - you can never create one, you can only move an existing one (i.e. split up the positive and negative parts). A magnetic field can be created, but that's because you always create a north and south at the same time. If magnetic monopoles existed you could not create just one, you could only separate the two halves.) Anyway, a wormhole would allow you to have a gravitational discontinuity and that's impossible, it would create a gravitational wave with an infinite frequency. As you know a true square wave is physically impossible - the fourier transform requires an infinite frequency - but that's what you are doing by moving matter via a wormhole.
      - openasocket 10y ago
        You're assuming the gravitational field can't permeate the wormhole. In your first scenario, the gravity well would extend out of the other side of the wormhole. A wormhole is in no way a gravitational discontinuity, the toplogy for them is well defined. The creation of a wormhole would be a bit tricky, as this does require a discontinuity, but there's no reason to think that's impossible. After all, a gravitational singularity is also a discontinuity, and physicists have no problem with that. Here's a concrete example: https://en.wikipedia.org/wiki/Ellis_wormhole https://en.wikipedia.org/wiki/Ellis_wormhole That's a wormhole with a well-defined metric that satisfies the Einstein field equations.
        ars 10y ago
        > You're assuming the gravitational field can't permeate the wormhole. In your first scenario, the gravity well would extend out of the other side of the wormhole. That would be even worse, I replied to the same thing here: https://news.ycombinator.com/item?id=12301858 https://news.ycombinator.com/item?id=12301858 > A wormhole is in no way a gravitational discontinuity A movable one certainly is, and a non movable one doesn't make any sense from a relativity point of view. > Ellis Wormhole Did you read your own link? "and there is no gravity" There's a reason they say that. And there is no place in the universe without gravity. It's a mathematical solution, not a representation of the physical world.
  - platz 10y ago
    Susskind's ER=EPR posits that entanglement is actually a form of proto-wormhole, and you could build a bridge through spacetime with two entangled black holes... it works pretty well without rewriting physics. though you couldnt send information from one side out the other. Einstein-Rosen bridge
    - ars 10y ago
      A wormhole with the same "trick" that entanglement does, where you can't actually send information/energy through it, would indeed not violate any laws. It would also be useless. But that's not what people mean when they say wormhole.
      - platz 10y ago
        To be more clear, the ER bridge would actually allow people on different ends to jump in and meet in the 'middle', they just couldnt then go back out (going from one side out the other). This was the closest thing to a wormhole i can think of (given the ER=RPR conjecture is true)
  - jgamman 10y ago
    i'm not commenting on the validity of what you say, just that it reminds me of the story of max plank and his photon 'hack' for getting round the ultraviolet catastrophe - he thought it was a mathematical tick/curiosity too. then Einstein said 'hang on hang on hang on, maybe not...'. wouldn't be the first time in history a hack turned out to be the real deal.
    - ars 10y ago
      There are a lot of mathematical things like that - tachyons for example are a mathematical "solution". The ultraviolet example is the opposite: The universe acted in a certain way, so we looked for math to match, which happened to have a strange property to it. Here first we found the strong property and are looking for the universe to match. You can do the first, but not the second.
      - knz42 10y ago
        Well of course we can do the second. It has happened all the way with the element table in chemistry. Heck we're even manufacturing non-natural matter (as in, probably never generated elsewhere in the universe) to fill the holes that the theory has created. The Higgs boson also comes to mind.
  - mcbits 10y ago
    The laws of physics are the mathematical description, and the wormhole concept arises as a curious edge case of those laws. If wormholes are actually impossible, the laws of physics already need to be rewritten, not the other way around.
    - ars 10y ago
      > the laws of physics already need to be rewritten, not the other way around. Then explain how you conserve energy when you move an item out of a gravity well via a wormhole. Or the even bigger problem I explain here: https://news.ycombinator.com/item?id=12301781 https://news.ycombinator.com/item?id=12301781
      - XorNot 10y ago
        By pushing hard enough to equalize the GPR you're removing by going into space? Consider an obvious example: a wormhole which connects two points on earth separated by 1m of real distance, at the same height. Theres no violation of conservation of energy because you did not gain or lose gravitational potential energy, and your start and end momentum is conserved.
  - DHMO 10y ago
    Do you disagree with Dr. Kip Thorne? https://en.wikipedia.org/wiki/Kip_Thorne#Wormholes_and_time_travel https://en.wikipedia.org/wiki/Kip_Thorne#Wormholes_and_time_... Wormholes for matter and energy are not incompatible with physics. We just probably won't ever see one like the one he proposed, because creating it would require manipulation of matter or gravity at extreme scale. But, it is wrong to say it is impossible. It is theoretically possible.
    - ars 10y ago
      > Do you disagree with Dr. Kip Thorne? What's there to argue with? He doesn't claim wormholes can exist. > because creating it would require manipulation of matter or gravity at extreme scale. Not extreme scale, using a type of energy that doesn't actually exist. i.e. it's not about the quantity of energy, it's the type. It's a mathematical result, not an actual thing. > But, it is wrong to say it is impossible. It is theoretically possible. No, it is not possible. See my other replies in this thread.
      - DHMO 10y ago
        You sure about that? "...calculations in semiclassical gravity suggest that quantum effects may be able to violate this condition in curved spacetime. Although it was hoped recently that quantum effects could not violate an achronal version of the averaged null energy condition, violations have nevertheless been found, so it remains an open possibility that quantum effects might be used to support a wormhole." https://en.wikipedia.org/wiki/Wormhole https://en.wikipedia.org/wiki/Wormhole
- Aelinsaar 10y ago
  The same math that describes the creation of an ERB, also makes them unsuitable for transit of even a single particle. There's also probably some question as to whether it would even connect to a distant part of our universe, since the math describes two different, asymptotically flat universes.
- deleted 10y ago
  [deleted]
- aaron695 10y ago
  > The field still moves slower than light. Everything moves slower than [the speed of] light. Unless you are in a scifiction story or a conspiracy theorist who believes in that sort of thing and stuff like perpetual motion machines.
  - wyager 10y ago
    Well yes, but if you introduce the kind of topologies you can get with wormholes, things can take the shorter path through the wormhole, so it "looks like" they are moving faster than light.
    - aaron695 10y ago
      No. You can't go faster than light. There are no loop holes. The paper bending, sticking a pencil through explanation is science fiction. That is faster than light travel and hence impossible.
      - PeCaN 10y ago
        Point is, you can go less distance at the same speed. Do less work, not faster work.
      - swsieber 10y ago
        Then what makes a worm-hole special? I always thought it was that a worm-hole made a smaller path between two points than could normally exist in plain space.
        antidamage 10y ago
        It's a hypothetical mechanism for the transmission of information. It's not taking a shortcut, it's just a different mechanism for getting there, in the same way entanglement propagation can't exceed the speed of light. And that's why this technique is being described as a wormhole - it's a relatively good simulation of one in terms of some of the measurements they want to make and can be used to carry one of the properties we think a wormhole should be able to carry.
deleted 10y ago
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exabrial 10y ago
Reminds me of a sci-fi movie I can't think of the name of... they end up on a ship and it's haunted or something
- deleted 10y ago
  [deleted]
- TheWiseOne3 10y ago
  I saw that also... It reran on sci-fi channel many times. Can't recall the name but it was pretty bad.
- ugh123 10y ago
  Event Horizon https://en.wikipedia.org/wiki/Event_Horizon_(film) https://en.wikipedia.org/wiki/Event_Horizon_(film)
  - exabrial 10y ago
    Yes! That's it. Well I got down voted so many times the movie must really not be a crowd favorite :D
    - ConceptJunkie 10y ago
      Maybe because the movie took a potentially awesome premise and totally whizzed it by turning it into a lame remake of Star Trek episode.
civilian 10y ago
If my memory from last year serves me, this is less a wormhole and more of a "magnetically-shielded tunnel". Cool and potentially useful, but I wish they didn't use the word wormhole.
- iaw 10y ago
  Yep, just read to the bottom. It appears like it has properties similar to that of a wormhole but its more cloaking.
- adrianratnapala 10y ago
  The paper says it is a > a tunnel for magnetic fields acting as if was outside the usual 3D space. I didn't understand what they meant by "acting as if it was outside the usual 3D space". If I did understand it then, fair enough, I'd accept the thing as a magnetic analogue of a wormhole, just as there are physically interesting hydrodynamic analogues of black and white holes. (https://arxiv.org/abs/1203.6505 https://arxiv.org/abs/1203.6505)
- gaur 10y ago
  > I wish they didn't use the word wormhole. Taking a hot physics buzz-phrase (wormhole, black hole, Hawking radiation, etc.) and applying it to a mathematically analogous (but physically unrelated) system is currently fashionable in physics. Personally I find it kind of dishonest, but it seems to be a popular strategy for focusing attention on research that is otherwise only marginally interesting.
  - abdullahkhalids 10y ago
    You stated the valid reason why physicists do this naming. The mathematics is analogous. This means that by studying the different system (eg. the wormhole in the lab), the physicists are probing the mathematical structure of the theory of the original system- except that studying the different system is easier than the original system. Actual wormhole physicists then might learn from this research to understand how wormholes might behave. Why this is a recent trend is because only in the past few decades have experiment technologies improved to the point where exotic systems can be physically simulated in the lab using simple systems. My own research is partly of this sort and so we have fancy names too, but I assure you that, at least in my group, no one cares one bit about our research being published in pop-sci magazines

106 points by jotux 10y ago

The interesting part of wormholes is that they introduce topologies that connect two extrinsically "distant" points, yes? This research doesn't appear to do that; it seems like it just "hides" the magnetic field for a distance. The field still moves slower than light.

ars 10y ago
The other interesting thing about wormholes is they don't exist, and can't exist without basically rewriting every law of physics we have. They violate almost every conservation law there is. They are a mathematical curiosity, not a thing that could actually exist. If you could rewrite the laws of physics there are lots of cool things you could do, wormholes would just be the start......
- derefr 10y ago
  It's the creation of wormholes that would violate physics, though, right? AFAIK our current model of physics would work just fine to describe a universe that came into existence with permanent, stable wormholes already in it; that'd just be part of its topology.
  - throw98172 10y ago
    Even an existing wormhole could still cause problems. Consider for example a wormhole between two points with different gravitational potential — say one end is close to the Earth and the other end is further away. Then if you could let yourself fall from the higher to the lower point, and took the wormhole to complete a loop, you would end the loop with more energy than you started with, which is a big no-no!
  - mahranch 10y ago
    He has it backwards. Our current physics allow for wormholes. They probably don't exist but if they were literally impossible, then we would need to rewrite our current physics. Wormholes are more than likely impossible because to hold one open for travel, you would need some sort of negative matter/negative energy. That isn't forbidden by physics, but it's unlikely that it exists since we haven't seen any. Without negative energy/matter to hold a wormhole open, even if you could create one, just a single proton or electron would cause the wormhole to become unstable and collapse in on itself, and doing so faster than the proton could travel through.
    - ars 10y ago
      > Our current physics allow for wormholes. No, it does not. See my more detailed reply here: https://news.ycombinator.com/item?id=12301781 https://news.ycombinator.com/item?id=12301781
  - ars 10y ago
    No. Using them is the problem. Say you are in a gravity well with one side of the wormhole, and the other side is outside the well. You could "lift" matter outside the gravity well without spending energy. There are other problems as well: Gravity has no discontinuities, as objects move, the gravitational field moves with it. You never have a situation where gravity just suddenly shows up. (The same is true for an electrical field BTW - you can never create one, you can only move an existing one (i.e. split up the positive and negative parts). A magnetic field can be created, but that's because you always create a north and south at the same time. If magnetic monopoles existed you could not create just one, you could only separate the two halves.) Anyway, a wormhole would allow you to have a gravitational discontinuity and that's impossible, it would create a gravitational wave with an infinite frequency. As you know a true square wave is physically impossible - the fourier transform requires an infinite frequency - but that's what you are doing by moving matter via a wormhole.
    - openasocket 10y ago
      You're assuming the gravitational field can't permeate the wormhole. In your first scenario, the gravity well would extend out of the other side of the wormhole. A wormhole is in no way a gravitational discontinuity, the toplogy for them is well defined. The creation of a wormhole would be a bit tricky, as this does require a discontinuity, but there's no reason to think that's impossible. After all, a gravitational singularity is also a discontinuity, and physicists have no problem with that. Here's a concrete example: https://en.wikipedia.org/wiki/Ellis_wormhole https://en.wikipedia.org/wiki/Ellis_wormhole That's a wormhole with a well-defined metric that satisfies the Einstein field equations.
      - ars 10y ago
        > You're assuming the gravitational field can't permeate the wormhole. In your first scenario, the gravity well would extend out of the other side of the wormhole. That would be even worse, I replied to the same thing here: https://news.ycombinator.com/item?id=12301858 https://news.ycombinator.com/item?id=12301858 > A wormhole is in no way a gravitational discontinuity A movable one certainly is, and a non movable one doesn't make any sense from a relativity point of view. > Ellis Wormhole Did you read your own link? "and there is no gravity" There's a reason they say that. And there is no place in the universe without gravity. It's a mathematical solution, not a representation of the physical world.
- platz 10y ago
  Susskind's ER=EPR posits that entanglement is actually a form of proto-wormhole, and you could build a bridge through spacetime with two entangled black holes... it works pretty well without rewriting physics. though you couldnt send information from one side out the other. Einstein-Rosen bridge
  - ars 10y ago
    A wormhole with the same "trick" that entanglement does, where you can't actually send information/energy through it, would indeed not violate any laws. It would also be useless. But that's not what people mean when they say wormhole.
    - platz 10y ago
      To be more clear, the ER bridge would actually allow people on different ends to jump in and meet in the 'middle', they just couldnt then go back out (going from one side out the other). This was the closest thing to a wormhole i can think of (given the ER=RPR conjecture is true)
- jgamman 10y ago
  i'm not commenting on the validity of what you say, just that it reminds me of the story of max plank and his photon 'hack' for getting round the ultraviolet catastrophe - he thought it was a mathematical tick/curiosity too. then Einstein said 'hang on hang on hang on, maybe not...'. wouldn't be the first time in history a hack turned out to be the real deal.
  - ars 10y ago
    There are a lot of mathematical things like that - tachyons for example are a mathematical "solution". The ultraviolet example is the opposite: The universe acted in a certain way, so we looked for math to match, which happened to have a strange property to it. Here first we found the strong property and are looking for the universe to match. You can do the first, but not the second.
    - knz42 10y ago
      Well of course we can do the second. It has happened all the way with the element table in chemistry. Heck we're even manufacturing non-natural matter (as in, probably never generated elsewhere in the universe) to fill the holes that the theory has created. The Higgs boson also comes to mind.
- mcbits 10y ago
  The laws of physics are the mathematical description, and the wormhole concept arises as a curious edge case of those laws. If wormholes are actually impossible, the laws of physics already need to be rewritten, not the other way around.
  - ars 10y ago
    > the laws of physics already need to be rewritten, not the other way around. Then explain how you conserve energy when you move an item out of a gravity well via a wormhole. Or the even bigger problem I explain here: https://news.ycombinator.com/item?id=12301781 https://news.ycombinator.com/item?id=12301781
    - XorNot 10y ago
      By pushing hard enough to equalize the GPR you're removing by going into space? Consider an obvious example: a wormhole which connects two points on earth separated by 1m of real distance, at the same height. Theres no violation of conservation of energy because you did not gain or lose gravitational potential energy, and your start and end momentum is conserved.
- DHMO 10y ago
  Do you disagree with Dr. Kip Thorne? https://en.wikipedia.org/wiki/Kip_Thorne#Wormholes_and_time_travel https://en.wikipedia.org/wiki/Kip_Thorne#Wormholes_and_time_... Wormholes for matter and energy are not incompatible with physics. We just probably won't ever see one like the one he proposed, because creating it would require manipulation of matter or gravity at extreme scale. But, it is wrong to say it is impossible. It is theoretically possible.
  - ars 10y ago
    > Do you disagree with Dr. Kip Thorne? What's there to argue with? He doesn't claim wormholes can exist. > because creating it would require manipulation of matter or gravity at extreme scale. Not extreme scale, using a type of energy that doesn't actually exist. i.e. it's not about the quantity of energy, it's the type. It's a mathematical result, not an actual thing. > But, it is wrong to say it is impossible. It is theoretically possible. No, it is not possible. See my other replies in this thread.
    - DHMO 10y ago
      You sure about that? "...calculations in semiclassical gravity suggest that quantum effects may be able to violate this condition in curved spacetime. Although it was hoped recently that quantum effects could not violate an achronal version of the averaged null energy condition, violations have nevertheless been found, so it remains an open possibility that quantum effects might be used to support a wormhole." https://en.wikipedia.org/wiki/Wormhole https://en.wikipedia.org/wiki/Wormhole
Aelinsaar 10y ago
The same math that describes the creation of an ERB, also makes them unsuitable for transit of even a single particle. There's also probably some question as to whether it would even connect to a distant part of our universe, since the math describes two different, asymptotically flat universes.
deleted 10y ago
[deleted]
aaron695 10y ago
> The field still moves slower than light. Everything moves slower than [the speed of] light. Unless you are in a scifiction story or a conspiracy theorist who believes in that sort of thing and stuff like perpetual motion machines.
- wyager 10y ago
  Well yes, but if you introduce the kind of topologies you can get with wormholes, things can take the shorter path through the wormhole, so it "looks like" they are moving faster than light.
  - aaron695 10y ago
    No. You can't go faster than light. There are no loop holes. The paper bending, sticking a pencil through explanation is science fiction. That is faster than light travel and hence impossible.
    - PeCaN 10y ago
      Point is, you can go less distance at the same speed. Do less work, not faster work.
    - swsieber 10y ago
      Then what makes a worm-hole special? I always thought it was that a worm-hole made a smaller path between two points than could normally exist in plain space.
      - antidamage 10y ago
        It's a hypothetical mechanism for the transmission of information. It's not taking a shortcut, it's just a different mechanism for getting there, in the same way entanglement propagation can't exceed the speed of light. And that's why this technique is being described as a wormhole - it's a relatively good simulation of one in terms of some of the measurements they want to make and can be used to carry one of the properties we think a wormhole should be able to carry.

deleted 10y ago

[deleted]

exabrial 10y ago

Reminds me of a sci-fi movie I can't think of the name of... they end up on a ship and it's haunted or something

deleted 10y ago
[deleted]
TheWiseOne3 10y ago
I saw that also... It reran on sci-fi channel many times. Can't recall the name but it was pretty bad.
ugh123 10y ago
Event Horizon https://en.wikipedia.org/wiki/Event_Horizon_(film) https://en.wikipedia.org/wiki/Event_Horizon_(film)
- exabrial 10y ago
  Yes! That's it. Well I got down voted so many times the movie must really not be a crowd favorite :D
  - ConceptJunkie 10y ago
    Maybe because the movie took a potentially awesome premise and totally whizzed it by turning it into a lame remake of Star Trek episode.

civilian 10y ago

If my memory from last year serves me, this is less a wormhole and more of a "magnetically-shielded tunnel". Cool and potentially useful, but I wish they didn't use the word wormhole.

iaw 10y ago
Yep, just read to the bottom. It appears like it has properties similar to that of a wormhole but its more cloaking.
adrianratnapala 10y ago
The paper says it is a > a tunnel for magnetic fields acting as if was outside the usual 3D space. I didn't understand what they meant by "acting as if it was outside the usual 3D space". If I did understand it then, fair enough, I'd accept the thing as a magnetic analogue of a wormhole, just as there are physically interesting hydrodynamic analogues of black and white holes. (https://arxiv.org/abs/1203.6505 https://arxiv.org/abs/1203.6505)
gaur 10y ago
> I wish they didn't use the word wormhole. Taking a hot physics buzz-phrase (wormhole, black hole, Hawking radiation, etc.) and applying it to a mathematically analogous (but physically unrelated) system is currently fashionable in physics. Personally I find it kind of dishonest, but it seems to be a popular strategy for focusing attention on research that is otherwise only marginally interesting.
- abdullahkhalids 10y ago
  You stated the valid reason why physicists do this naming. The mathematics is analogous. This means that by studying the different system (eg. the wormhole in the lab), the physicists are probing the mathematical structure of the theory of the original system- except that studying the different system is easier than the original system. Actual wormhole physicists then might learn from this research to understand how wormholes might behave. Why this is a recent trend is because only in the past few decades have experiment technologies improved to the point where exotic systems can be physically simulated in the lab using simple systems. My own research is partly of this sort and so we have fancy names too, but I assure you that, at least in my group, no one cares one bit about our research being published in pop-sci magazines