Wormholes, parallel universes, negative mass

[hammertime]

Hi. I have a few questions.

Is it theoretically possible to build a wormhole to a parallel or baby universe? Could a sufficiently advanced civilization do this? Could negative mass play a role in it? Could something else?

 

[Soff]

I think if we can answer these questions, we would know a lot more about our universe. As far as I know, there are some calculations which show that the existence of a wormhole to a parallel is indeed possible (Hawking,...).

However, it's not that easy... I assume that we must use a enormous amount of energy to create such a wormhole. Therefore, the physics in this environment will be a lot more complex than it is here on earth.

 

[MrXow]

Nobody knows what happens in the singularity of a black hole.

 

[pervect]

Hi. I have a few questions.

Is it theoretically possible to build a wormhole to a parallel or baby universe? Could a sufficiently advanced civilization do this? Could negative mass play a role in it? Could something else?

We do know that it would require a time machine to build a wormhole classically. There's a quote about this from Thorne that I can probably dig up if pressed, it's in his semi-popular book Black Holes, Wormholes & Time Machines, which also has a reference to the peer-reviewed paper that derives this result. I don't know if "baby universes" were even considered in this paper (probably not).

Thus most papers on wormholes (that I'm aware of, anyway), focus on finding a "quantum wormhole" and keeping it open, rather than building one.

If you want to look at the professional literature on wormholes, you might start with the Moriss-Thorne paper,

http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=AJPIAS000056000005000395000001&idtype=cvips&gifs=yes

though you'll most likely need to go to a library to get access to it.

If you are interested in semi-popular works, I would recommend Cramer's "Alternate Views" columns, which are available online, see for instance

http://www.npl.washington.edu/av/#6

We also know that it will take exotic matter (what you probably mean by negative mass) to hold open a wormhole throat.

 

[hammertime]

Different constants

But wouldn't a parallel and/or a baby universe have different physical constants and vacuum energy from our universe? Thus, wouldn't we be destroyed once we entered the other universe?

 

[pervect]

But wouldn't a parallel and/or a baby universe have different physical constants and vacuum energy from our universe? Thus, wouldn't we be destroyed once we entered the other universe?

It's not particularly clear how to translate "baby universe" into an exact mathematical form where the question might be answered.

There are other issues relating to what "different physical constants" might mean, for that matter. If we take a specific example, "What happens if we open a wormhole with two different values of the fine structure constant on each end", this is not a topic which GR could address as it is not a complete theory of quantum gravity. I don't think current quantum gravity is advanced enough to answer this question, either, but I don't know that area very well.

The topic of 'different physical constants" comes up a lot, for an interesting but rather long paper on it see

http://www.iop.org/EJ/article/1126-6708/2002/03/023/jhep032002023.pdf?request-id=4DKqigmP3BGYZK_A2wi7Kg

I'll quote one view that I have some sympathy with, note that the three authors of the above paper each have differing views:

The idea of imagining a universe with different constants is not new, but, in my opinion,
the early literature is very confusing. For example, Vol'berg [17] and Gamow [18] imagine a universe in which the velocity of light is different from ours, say by ten orders of magnitude, and describe all sorts of weird effects hat would result:

The initials of Mr. Tompkins originated from three fundamental physical constants: the velocity of light c; the gravitational constant G; and the quantum constant h, which have to be changed by immensely large factors in order to make their effect easily noticeable by the man on the street."

In this one sentence, Gamow manages to encapsulate everything I am objecting to!
First, he takes it as axiomatic that there are three fundamental constants. Second, he
assumes a change in these constants can be operationally defined, I for one am mystified
by such comparisons. After all, an inhabitant of such a universe (let us identify him with
Feynman's alien) is perfectly free to choose units in which c = 1, just as we are. To use
the equation

k = E/c

to argue that in his universe, for the same energy E, the photon emitted by an atom would have a momentum k that is ten orders of magnitude smaller than ours is, to my mind, meaningless. There is no experimental information that we and the alien could exchange that would allow us to draw any conclusion.