Could Black Holes Be Portals to Other Universes?

David Shiga writes "Astronomers have identified many objects out there that they think are black holes. But could they be portals to other universes called wormholes, instead? According to a new study by a pair of physicists, we wouldn't be able to tell the difference. They have discovered that wormholes with the right shape would look identical to black holes from the outside. But while a trip into a black hole would mean certain death, a wormhole might spit you out into a parallel universe with its own stars and planets. Exotic effects from quantum physics might produce wormholes naturally from collapsing stars, one of the physicist says, and they might even be produced in future particle accelerator experiments."

The paper

[Ambitwistor]

New Scientist has a link to the paper, which is small and off to the side and easily overlooked (and does not make clear that the whole paper can be accessed, not just the abstract). The paper is here [arxiv.org] for anyone who may have missed it.

Re:I can only imagine

[suv4x4]

"But while a trip into a black hole would mean certain death, a wormhole might spit you out into a parallel universe with its own stars and planets."

Err.. something's gotta be wrong here. First of all, let's face it: you'll be dead never mind if it's a portal or not. The fact that my energy will somehow exit on the other end offers little comfort, knowing that to be alive, I need to also have my structure preserved.

The idea about wormholes was introduced when experimenting (mathematically) what would the opposite of a black hole be, using just the known laws of physics and math.

The thing is, most objects in the universe have their exact opposite version (the most trivial example being matter and antimatter), so scientists thought the same might apply to black holes. Lots of new object classes were prophesied this way.

Thus, the concept of a while hole was born, which is not like a black hole at all: instead of only sucking in matter and energy (ignoring Hawking radiation for a moment), white holes can only emit matter and energy. Naturally, this posed the question, where is this matter coming from? And the obvious answer was: from a blackhole that's elsewhere. So a wormhole is in fact the whole mechanism where a black hole is tied to a white hole, and whatever falls in a black hole, comes out the white hole.

So I don't know what those scientists are talking about, but either is the article written very poorly, or the term "wormhole" is being used totally inappropriately here.

A "wormhole" can't look the same as "blackhole". It's like saying that a computer (the whole thing) may look to a keyboard (the input only). A wormhole isn't some sci-fi generic space warp where you put your ship to go to Degoba.

And you're definitely dead either way, but if you're brave, up on the next shuttle and go try it, in case a wormhole is passing by.

Logical contradiction

[Anonymous Coward]

Sorry to split semantic hairs here...but we are geeks after all...

The word "universe" logically means "everything." From Dictionary.reference.com [reference.com]:

1. the totality of known or supposed objects and phenomena throughout space; the cosmos; macrocosm.

An etymological analysis reveals the word to be of Latin origin, the prefix "uni" meaning "one" and "verse" derived from the word for "to turn," implying something to the effect of "all things turned to one." (I also have a beef with the misuse of "uni" in such words as "unisex," but I won't get into that here).

Anyway, if it is possible to get to a "parallel universe" then that means that it exists. If it exists, then that means that it is already part of the universe. Therefore saying that there are many universes is a simple logical contradiction.

So, perhaps these other places exist, and are parallel to the place in which we exist. I am envisioning something like a stack of 4 dimensional space-time continuums all lined up along a fifth dimension, with worm holes propelling objects along the 5d axis between these continuums. That may be possible for all I know, but they aren't parallel universes; they are all part of the universe.

Re:what would happen on the other side?

[maraist]

I can't remember the original source.. But in the book 'The God Delusion', there were references to several official big-bang theories.. One of which was the hypothesis that black-holes represent spontaneous synthesis of isolated sub-universes. Where information doesn't leak-back-in to the source universe.. Each sub-universe could have potentially deviant quantium properties such that the mass, charge, force-strenght, etc of various quantum particles would differ ever so slightly.. That by this process, universes actually evolve - ones that have unstable quantum characteristics quickly devolve (perhaps expanding too quickly, or collapsing back into itself, etc).. By virtue of the fact that our universe survived long enough to spawn life, this would represent a successful set of quantum characteristics - though there may be alternate sister, parental or child universes with more ideal states.

But, it stands to reason that such evolutionary universes don't allow cross-talk, that you wouldn't be able to worm-hole back into your neighboring universe. If nothing else, the difference in quantum properties would cause your physical person to become highly unstable.

Of course it's still conceivable that the sister universes have identical properties (that there is only one set), that perhaps only the differing ratio of particles (such as the over-abundance of matter v.s. antimatter in our universe). To which we may still survive in the alternate universe - just have to watch out for our alter ego.

Though, to me, an identical universe, or even a sister universe is kind of boring to me.. Just seems like infinity times k. whop-ti-doo. The only interesting cases to me, are the evolving universes or the true singularity of our universe.

String Theory

[kmac06]

This sounds like it's based on string theory. String theory has absolutely no evidence that it is correct--it just sometimes appears to describe some phenomena better than quantum mechanics or general relativity. I think of it more as a interesting mathematical construct rather than anything like a physical theory.

**Warning: Parent is a Goatse redirect**

[eternalnyte]

For those of you at work, beware the obligatory goatse reference the parent decided to post

Now I know I am getting too old....

[Anonymous Coward]

While extremely interesting, the same old stuff rehashed with little new information to add. I thought it was just computer science technology and topics that are continuously being rediscovered here (look at the Burroughs B5000 architecture from the 50-60s for an example).

Clear time to stop looking at /. and spend more time in the journals, or anywhere...

Re:Universal gravity

[Ambitwistor]

Which is actually something that's been bothering me since I thought of it: I feel like there's a tendency in cosmology to forget that time is also a dimension, and that the big bang is an expansion not of SPACE, but of SPACE-TIME.

No. "Expansion" refers to space, specifically an increase of spatial distances over time.

However, it is true that spacetime is curved.

So if space and time is expanding, how can it be something that is taking time? How can time be expanding along a timeline?

That's one of many reasons why nobody speaks of "spacetime" expanding. It doesn't have a meaningful definition.

This is an issue of semantics, not of physics.

I get the feeling, in all these many multi-dimensional theories of our universe, that it's a mistake to think about "time" as being somehow distinct and "special" as a dimension.

Geometrically, it is distinct and special. It's because the geometry of spacetime is described by a modified Pythagorean theorem (a Lorentzian metric), in which the sign of a (squared) timelike displacement is opposite to that of a spacelike displacement.

Space and time are unified into spacetime, but that doesn't mean that space and time are the same thing. Rather, it means that what is "space" to one observer may be a mix of "space and time" to another. However, all observers agree on whether a direction is overall timelike or overall spacelike.

But in that case, does time play some special role in the big bang?

In general relativity, time isn't even defined at the Big Bang; the geometry of spacetime breaks down. In a replacement theory of quantum gravity, who knows ...

Re:String Theory

[davidoff404]

This isn't based on string theory at all. If you read the actual paper [arxiv.org] you'll see right in the first section that it's based on a classical solution to the field equations to general relativity. More specifically, this classical solution is used to motivate the essential structure that the worm hole should have while later on in the paper they appeal to some very standard quantum field theory to imply that the weak-field Hawking radiation obvserved from this classical solution should appear essentially identical to that seen in corresponding black hole solutions to Einstein's field equations. The paper is reasonably interesting but, given that it completely ignores boundary conditions at (spatial) infinity and that it makes no mention of the fact that this solution presumably violates the positive mass theorem, I'm completely underwhelmed by it.

I'm as sceptical about string theory as anybody, particularly given that it's the area in which I actually work, but this particular paper is based purely on classical general relativity and quantum field theory with the Poincare group as a symmetry group.

Re:Into the Unknown: The Circle

[Anonymous Coward]

No, No, NO!

It was a Steven King story, but Alfred Bester coined the word "Jaunte" in The Stars My Destination. Bester also developed the whole idea of almost-instantaneous space travel in the very same.

I love SK, but the canon is still the canon, dude - credit where it's due.