Wormholes in Space

[vicky_molokh]

Originally Posted by lwcamp

There really are no walls. Not in space-time, anyway. The local wormhole traffic authority might put some up. Or maybe the engineers need to put up walls in order to make the wormhole work.

There is one direction where, if you move with a component of your velocity in that direction, you go through the wormhole and end up on the other side. The other two directions are periodic - if you move in the plane defined by those two directions you will eventually circle back around to end up where you started again. If your velocity has components along both the perpendicular and parallel directions to the throat, you will spiral around. This means that if you look in the direction perpendicular to the throat, you will see wildly distorted ring-images of yourself from the light that you emit which comes back around into your eye.

Luke

So if I don't align properly before exiting the wormhole, I'll get split in half by the mouth?

[Flyndaran]

Sounds like old school Zelda. If you follow the correct sequence of screen changes you get where you want. Otherwise you just keep coming back into screen.

[Anthony]

Originally Posted by vicky_molokh

So if I don't align properly before exiting the wormhole, I'll get split in half by the mouth?

No, just changes the direction you exit the hole.

[Sindri]

Originally Posted by lwcamp

Note that the diametric drive has net zero mass, so is probably prohibited by the quantum limits that prohibit other forms of negative mass without even more positive mass around to balance it. It is also unstable in many ways.

There are Krasnikov tubes, something like FTL railways in space, but if you have wormholes then Krasnikov tubes don't get you anything you don't already have and probably cost a lot more.

There are Alcubierre style warp drives. But the more we look at these, the more we realize how problematic they are (you can't turn them off, they destroy their destination, they destroy the traveler, and in an asymptotically flat space-time like ours you probably can't turn them on, either).

The diametric drive did sound problematic. How solid is this requirement for negative mass to be surrounded by positive mass?

Yeah Oh I should have mentioned Krasnikov tubes and Alcubierre drives too. I was actually considering the Krasnikov tube first and just checking wormholes out to see if they would be an alternative. However I thought Krasnikov tubes required less then a wormhole? I had a concern that since a Krasnikov tube is a warping of space the relative motions of the places you wanted to get to would leave it steadily farther away.

Originally Posted by lwcamp

Also, on another note, I just want to make sure that you are aware that wormholes conserve all the usual conserved quantities (energy, momentum, angular momentum, electric charge, and in non-relativistic cases, mass) and do so locally. So a wormhole mouth gains the mass of anything that goes through it (and momentum, electric charge, etc.) and loses the mass (& etc) of everything that comes out of it. Thus, if you find a wormhole out to the middle of intergalactic space where the far end has a mass of only a few hundred hydrogen atoms, you can't put anything through the wormhole with a mass of more than a few hundred hydrogen atoms before the mass at the far end goes negative and the whole structure probably collapses. Preferably, your wormhole ends up inside a massive object so you can grab some mass from outside and stuff the wormhole with it to bulk it up.

Luke

That's odd, I would have thought that it didn't work that way since it would require colonists to work a bit for their supplies.

[lwcamp]

Originally Posted by vicky_molokh

So if I don't align properly before exiting the wormhole, I'll get split in half by the mouth?

If you move though the wormhole too fast, tidal forces will rip you into pieces. However, if you go slowly enough and you can stand the static tides, the fact that your body is held together by chemical bonds will overcome the tidal forces that tend to send you in all directions.

I think that is a reply to what you were asking about, but I am not entirely sure.

Luke

[lwcamp]

Originally Posted by Sindri

The diametric drive did sound problematic. How solid is this requirement for negative mass to be surrounded by positive mass?

It is a prediction of quantum field theory, and all known examples of stuff with negative energy are always surrounded by nearby areas that overcompensate with positive energy. To get around it, you probably need negative energy stuff that is not quantum mechanical.

Originally Posted by Sindri

That's odd, I would have thought that it didn't work that way since it would require colonists to work a bit for their supplies.

Physics doesn't really care how hard colonists have to work for their supplies.

In any event, what it means is that in order to keep mass balance, the colonists have to send back boat-loads of rocks or something for the boat-loads of supplies they get. If everything goes well, the people on the other side will put a high value on those rocks (because of ores or precious metals or because instead of rocks the colonists sent lumber or grain or beef or macguffinite plants that produce anti-aging medicine or something). If you get about the same amount of traffic going both ways, you don't have to worry about it much (the wormhole traffic authority and mass utility have to worry about it, but this is along the lines of worrying about highway repair or pumping stations in a modern setting). If the traffic is heavily lop-sided, you occasionally have to load up a barge with heavy rocks or something and send it back.

Luke

[Anthony]

Originally Posted by lwcamp

In any event, what it means is that in order to keep mass balance, the colonists have to send back boat-loads of rocks or something for the boat-loads of supplies they get.

And you'd better hope that the hole doesn't care about baryon or lepton number.

[Sindri]

Originally Posted by lwcamp

It is a prediction of quantum field theory, and all known examples of stuff with negative energy are always surrounded by nearby areas that overcompensate with positive energy. To get around it, you probably need negative energy stuff that is not quantum mechanical.

What does quantum mechanical mean in this context? Like casimir effect stuff instead of normal stuff only with negative mass?

Originally Posted by lwcamp

Physics doesn't really care how hard colonists have to work for their supplies.

I should hope not! That sentence was missing a bit.I meant to say that it was good anyway since it made colonists work for their supplies. I still find it weird that it doesn't operate like normal space in that way though.

It's nice because it slows down the extent to which a developed world can throw what for it is trivial energy at a new colony to speed up it's development to the speed at which the colony can get rocks.

[Ulzgoroth]

Originally Posted by Sindri

It's nice because it slows down the extent to which a developed world can throw what for it is trivial energy at a new colony to speed up it's development to the speed at which the colony can get rocks.

That's...probably not much of an issue really. A colony isn't going to be importing bulk matter, that just doesn't make much sense. So you orbit a million tons of asteroid through the wormhole, and you can pass a million tons of nanocircuits and fabricators the other way...

[Sindri]

Originally Posted by Ulzgoroth

That's...probably not much of an issue really. A colony isn't going to be importing bulk matter, that just doesn't make much sense. So you orbit a million tons of asteroid through the wormhole, and you can pass a million tons of nanocircuits and fabricators the other way...

I didn't say anything about importing bulk matter. The "getting rocks" is getting rocks on their side to throw through the wormhole so they can import stuff.