Microscopic Wormholes Possible in Theory | Hacker News Reader

Microscopic Wormholes Possible in Theory

phys.org

43 pointsdnetesn21 comments

You could probably get high frequency traders to fund research into this.

I would read a Greg Egan story about this, a la Crystal Nights.

you know what's even better that greg egan books? greg egans physics notes explaining the universe of his books: https://www.gregegan.net/ORTHOGONAL/01/DualPythagorean.html

As a person with minimal academic physics experience, I've occasionally wondered if the action of passing mass through a wormhole would violate the conservation of energy.

Say if one side of a wormhole is near an astronomical object, and another in an arbitrary point in empty space, then would the change in potential energy of the transmitted mass due to gravity be converted to another form?

If it were the case that the field of gravity were to be transmissible through a wormhole, then would opening or closing a wormhole consume or release an enormous amount of energy equal to the change in potential energy of the surrounding matter?

I suspect the time dilation could also be an issue, where objects passed through a wormhole are stretched or compressed akin to gravitational spaghettification, or if objects surrounding the wormhole experience time dilation due to the stretched spacetime.

>If it were the case that the field of gravity were to be transmissible through a wormhole

If I'm not mistaken, existing wormhole theories generally require the presence of "negative energy/mass", which I believe is considered to be repelled by gravity instead of attracted to it.

Combined with the fact that, under general relativity, wormholes and gravity both involve significant bending/shaping of spacetime (I think), I imagine it's really difficult to think about how wormholes interact with gravity coming from the perspective of how typical energy/mass does.

If you can pass photons through those microscopic wormholes, and put the end point of a lot of them in specific places in the spacetime, you get the argument of Light of other days, from Stephen Baxter and A.C.Clarke.

If you could pass photons from arbitrary points in the past you'd have Light of Other Days. You'd also break causality in ways which would be problematic, because removing photons is communication back in time; it's probably not physically possible.

However, once you have a stable wormhole, you could send one end to the future using time dilation (like in the Xeelee cycle)

Then people then can look back to us

A note to myself: “in theory” here means “hypothetically.”

Does it? The physics is beyond me, but the article doesn't seem to imply that this is based on a specific, not commonly accepted, hypothetical.

Any hypothesis that has wormholes without exotic matter is very interesting.

Even if you can't go faster then light (wormhole geometry still might conspire to prevent it), the utility of being able to shoot straight line traversals of radio waves through the planet that cannot be intercepted in real space would be huge.

> "Moreover, such a wormhole would be unstable. If for example a spaceship were to fly into one, it would instantly collapse into a black hole—an object in which matter disappears, never to be seen again. The connection it provided to other places in the universe would be cut off."

Can anyone expand on this?

I think (just a guess) that a wormhole is essentially a place where gravity is basically infinite (or at least at black hole levels), and that's what's connecting the parts of spacetime.

i.e. in order to warp spacetime enough, you need massive gravity. Or negative mass.

So any object passing through would be squashed to nothing.

So a wormhole is like a 2d segment version of a black hole?

Sounds like white holes.

https://youtu.be/S4aqGI1mSqo

> Can anyone expand on this?

I think it's a somewhat garbled description of the Einstein-Rosen bridge, which is a feature of the maximally extended Schwarzschild spacetime--you can see a diagram of this spacetime in [1]. Roughly speaking, this spacetime has two "exterior" regions that look like an ordinary universe with a spherically symmetric gravitating object at its center (these are regions I and III in the diagram). The gravitating object that you can actually see (as in, receive light signals from) in the exterior region is a white hole (region IV in the diagram); but if you try to fly into the white hole, you can't get inside--you end up inside the black hole instead (region II in the diagram).

The "Einstein-Rosen bridge" interpretation comes from viewing this spacetime in the coordinates used in the diagram, which are not the same as the natural coordinates of an observer in either exterior region. In the coordinates used in the diagram, it looks like you have two disconnected universes (regions I and III are disconnected at the bottom) that get connected by a spherical "wormhole" or "bridge" which starts at zero size, expands to a surface area of 4 pi M^2, where M is the "mass" of the hole, and then shrinks back down to zero size and vanishes, leaving two disconnected exterior regions again (regions I and III are disconnected again at the top). The bridge shrinks too fast for anyone in one exterior region to fly through it and reach the other exterior region; any attempt to do that ends up with you trapped inside the black hole (region II) and destroyed in the future singularity.

[1] https://en.wikipedia.org/wiki/Kruskal%E2%80%93Szekeres_coord...

“Everything is possible, in theory.” (Unknown)

I like to interpret all statements ending 'in Theory' as referring how things are done in 'Theory' - a small island nation in the Mediterranean, east of Malta and just to the west of Sardinia.

Renowned for their engineering, they produce wonderfully efficient refrigerators and air conditioners.

They're not just possible in theory, they're where my socks end up.

So deja vu possibley could just be some un-measurable and emphemeral microscopic wormhole that simply just opened up for a briefest period of time and space changing the ratios in your head. :-)

I think this would be more likely to cause an aneurysm than a deja vu :)

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