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Comment by kenbellows | Hacker News Reader

But... but it's not a wormhole. Not in the usual sense of the word anyway. When I think of a wormhole, I think of a "hole" through spacetime that transfers something from point A to point B by entirely bypassing all the space in between; this is not that at all. It's more like a cloaking device. The magnetic field still travels the whole distance in exactly the same way that it would, it's just not visible to an outside observer. Still super awesome, I just wish they wouldn't use the word "wormhole".

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I wish it could become standard operating procedure around here to place quotes around scientifically linkbaiting terms like "wormhole" in article titles, lest they be mistaken for fact.

Also, to save everyone the trouble of getting their hopes up in the future:

- It's not a wormhole. It's never a wormhole.

- Quantum teleportation and quantum entanglement don't mean what you (probably) think they do, and neither allows for faster than light communication anyway. No, not even then.

- It doesn't really make things invisible, it just makes a narrow part of the electromagnetic spectrum difficult to detect under experimental conditions, and that part probably doesn't include visible light.

- It can't really read your thoughts.

- It's (probably) not really artificial intelligence.

- It's not antigravity. It's never antigravity.

- It's not a warp drive. It's never a warp drive.

- They almost certainly didn't get cold fusion working this time.

- All solutions to the Fermi paradox are handwaving nonsense until proven otherwise.

If I read it right, the magnetic field does not "disperse" through the channel; it's as strong at the exit as at the entrance.

It's not a shortcut in the speed-of-light sense, but it does appear to change the topology of space from the field's perspective.

When this was reported there the other week (through some summary article), it was unclear to me. I was looking, because my first thought was that if it's actually skipping that space, and if it's instantaneous, isn't that FTL communication? You could encode information in magnetic fluctuations.

Indeed. The light speed limit is only valid when moving through space. If you bypass it, nothing actually stops it from having FTL (Faster Than Light) communications/travel.

To understand wormholes or portals from the Valve game, you can think of our 3D universe as a 2D sheet of paper. You cannot move along the sheet of paper faster than light; however, if you bend the piece of paper, you can make it so that two different points on the sheet touch.

A wormhole is just this pair of points, and finding a way to switch between the two connected pieces of paper. Since those two points are actually in the same location, traveling from one to another should be instantaneous.

It is disingenuous to call it a wormhole. It would be more accurate to call it a shielded conductor of magnetic field lines.

This is no more a wormhole for magnetism than a coaxial cable is a wormhole for RF signals.

Well, minus that whole wire thing.

It is a hole through space, not through time. Am i right?

From the abstract of the Nature article linked by @comboy below (http://www.nature.com/articles/srep12488):

> the magnetic field from a source at one end of the wormhole appears at the other end as an isolated magnetic monopolar field, creating the illusion of a magnetic field propagating through a tunnel outside the 3D space.

Seems that there's no actual tunneling, just the illusion of tunneling.

The article is in the journal Scientific Reports, not Nature. Nature Publishing Group is the publisher of that journal.

Also, note that Scientific Reports has no requirements for a paper to be super-novel/cool/hot topic, in contrast to the actual Nature journal. Anything which is decent science will get published in SRep; it's NPG's version of PLOS One.

It seems Nature's strategy is working here, since many news outlets and the general public don't seem to be aware of the difference.

Relativity actually tells us what real "holes in space" do. I'm not kidding. And the answer is that they explode as they collapse, releasing massive amounts of energy as the vacuum is disturbed, because any macroscopic spatial distortion is massively, massively energetic, in the sense where all my uses of the word "massive" is not actually metaphorical. Explosions equivalent to rather enormous amounts of mass, as energy.

No, there's no hole through space here.

How would you do a calculation on that (energy from collapsing hole through spacetime)? I've googled to get somewhere but I can't find anything useful.

Ianahep, but maybe work backwards from gravity vs spacetime equations? I'm assuming gravity is the exchange mechanism that drives this, so if you needed x gravitational field to produce y displacement, then given y displacement you have some energy equivalent of x in mass?

A starting point is "stress-energy tensor" as a keyword to search.

When taking General Relativity I did that calculation as part of the take-home exam. It's mostly a matter of calculating the curvature tensor of a wormhole and finding that it is freaky, so the energy-momentum tensor that would satisfy the Einstein equation would need to include negative energy and/or momentum (the Einstein equation basically says curvature tensor = energy tensor(1)). Then exactly how the thing would unravel is a matter of computation, but unravel it would.

Or one could presumably find a form of matter that has negative energy density and start building wormholes.

1) The energy tensor has energy as the time diagonal value, and momentum as the space diagonal values.

Protip: googling for the energy required to create such a wormhole is a better solution. That lands you on this BBC story[1] where they've interviewed well-known physicists, and state that

"As a very rough approximation, you would need the energy the sun produces over 100 million years to make a wormhole about the size of a grapefruit."

[1] http://www.bbc.com/future/story/20140326-will-we-ever-travel...

So approximately the energy equivalent of the mass of 2 earths.

Seems doable.

Depends what you mean by a "hole through space"? Yes, its a physical passageway that itself consumes space, like a physical tunnel you would drive your car though. The magnetic field is traveling through space, through a shielded device that also takes up space.

Think of this like Fiber Optics, they are "wormholes" for light, or Electronic wires, they are "wormholes" for electricity. The wormhole is just a metaphor for the illusion.

It would have been insane to open up Hacker News and read "Cloaking device has been invented"...what are we, Romulans?

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