# Q: Are white holes real?

Physicist: The Big Bang is sometimes described as being a white hole.  But if you think of a  white hole as something that’s the opposite of a black hole, then no: white holes aren’t real.

They show up when you describe a black hole using some weird coordinates, so they’re essentially just a non-real mathematical artifact.  However, white holes are a cute idea so they show up a lot in sci-fi.  White holes are a mathematical abstraction that necessarily exist in the infinite past.  That is to say, if you follow the mathematical model that physicists use, you’ll never have a situation where a white hole exists at the same time as anything else.  Its existence happens infinitely long ago.

Spacetime gets seriously messed up near and inside of a black hole.  To make the math easier, and to help make the situation easier to picture, the Kruskal-Szekeres coordinate system was created.

In this (very unintuitive) diagram straight lines through the center are lines of constant time, with the future roughly up.  The event horizon of the black hole is also the infinite future (from an outside perspective it takes forever to fall all the way into a black hole).  That should make very little sense, but keep in mind: black holes and weird spacetime go together like Colonial Williamsburg and a lingering sense of disappointment.  The black hole’s interior is the upper triangle, the entire universe is the right triangular region and the white hole is the lower region.

The boundary of this lower region is in the infinite past.  That is; in this goofy mathematical idealization of a static and eternal black hole, a white hole shows up automatically in the infinite past.  One of the issues here is that black holes need to form at some point (in the finite past).

Taking this model completely seriously and assuming that it implies that white holes are real is a little like saying “imagine an infinite robot-godzilla”, and then worrying about where it came from.  It’s an abstraction used to think about other things.  Physicists love themselves some math, but the love is tempered by the understanding that writing down an equation doesn’t make things real.

Physicists love themselves some math, but (almost always) recognize the scope and limitations of their own equations.

For example, we can talk about the location “North 97°, East 40°”, but that doesn’t make it exist (North 90° is the north pole, the farthest north you can get by definition).

Sci-fi is about the only place you’ll hear people talking about white holes.  Whites holes are the opposite of black holes: they spit out matter and energy, they’re impossible to enter, they’re very bright, that sort of thing.  In fiction “the opposite of…” is a great way to get weird new ideas (e.g., Bizarro Superman).

The Einstein picture was created here.

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### 16 Responses to Q: Are white holes real?

1. Boris Borcic says:

You write from an outside perspective it takes forever to fall all the way into a black hole.

Does this not mean that can be somehow opposed – and all the more relevantly with the current debates of firewalls – to the classical notion of “no drama” at the horizon for the infalling observer, that the geometry of his past light cone undergoes a discontinuity at that event?

(I posted essentially the same question a few weeks back on a years-old post on this blog, that I can’t retrieve at the moment; so I am making sure to check notification of followup comments)

2. rigney says:

Not trying to show off my ignorance, but from Newton on to Einstein etc., other than for some very fancy calculus, I see gravity as nothing more than an act of magnetism in disguise. If black holes exist, I attribute them to this powerful entity. I love science with a passion, but unfortunately not smart enough to grasp it other than elementary. As I understand it, black holes have a vacuuming effect similar to pulsars. So, since all atoms have certain magnetic properties, perhaps black holes are nothing more than giant magnets? A white hole on the other hand, if such a thing exists, may have been the white light seen as our universe began.

3. Flavio says:

Analogously, aren´t the imaginary numbers used in the schrodinger equation and on the equations of m theory just an abstract, not apliccable model?

4. The Physicist says:

The complex numbers found in quantum mechanics are extremely important, and QM can’t (cleanly)be done without them. However, they don’t directly show up. They just work in the background. There’s an old post about that here.

5. Phyllis McLemore says:

Lucky I read the Seth books channeled by Jane Roberts. Otherwise I would have no reason to be interested in physics.
Seth is an energy being that vibrates in a “parallel reality”. Seth says that there are as many colors of holes as there are colors. And these holes are the enter and exit points that energy takes when traveling through different wave lengths. People form these tunnels from intent because we choose to be here. Our choosing forms the tunnel to this frequency creating these holes at both ends. Birth is the end of the tunnel literally. Some books say that we are still attached by a cord to the reality we came from. That means that hole is our connection to the “other side” people talk about.
I don’t understand the cord, though, because as beings of energy and light it would seem to me that I could travel in and out of …..why do these bodies we create have to have cords to another world, the light world we come from?
These bodies are so dense that they don’t vibrate fast enough to keep the connection.

6. white Holes are mathematical fantasy and nothing else, nature is more simple the only thing we need a deeper thinking and clearer understanding…. in order to explain one thing we do not need to add or decorate with additional features that it becomes more complex to understand it……….. my first question ? is our universe finite or infinite… if infinite then our universe has not originated from the big-bang …….. because within a limited time (i.e. 13.7 billion years). it cannot shoot out to infinity……. if it is finite then it has a big-bang origin and it expand to infinity unless the time permission is infinite….!!

7. John David Dunson says:

@juges debnath: There can be both an infinite universe and a Big Bang. I think most people assume that the “universe” expands with the matter from the Big Bang, but that has never made sense to me. What does make sense to me is that the universe is already infinite, and the matter from the Big Bang will keep expanding into it forever. Otherwise, we would eventually expand all the way to the edge of the universe. @rigney: You can’t say gravity is like magnetism because magnetism has poles that can push as well as pull. @Boris Borcic: This doesn’t affect Alice’s fall. It’s only talking about what her fall will look like to Bob (an outside observer). Her own frame of reference is where the debate over no drama vs firewall comes into play. @Flavio: Imaginary numbers are very important and very “real”. They also play a huge role in electrocity/electronics engineering calculations.

And there are primordial black holes. Low mass, high Hawking radiation, LITERALLY white holes.

9. Bob says:

Well, primordial black holes (or black holes of small mass) do emit a whole lot of radiation. However, you have to make the black hole first, which means putting in matter/energy. So once the black hole evaporates via Hawking radiation, you don’t have a net gain of energy.

To Physicist: If white holes violate conservation of energy, then how could they exist? Is there a “weird” theoretical way that white holes could work around or avoid this law?

10. The Physicist says:

In part because there’s no positive evidence, and in part because of problems like you mention, it’s fair to say they don’t exist.

11. Swapnil says:

Whats with Stephen Hawking’s new statement where he said that black holes do not exist?

12. Xerenarcy says:

some simple arguments why a white hole cannot exist:

1. a white hole is often used to explain where all the stuff in a black hole goes; a black hole in universe A, leads to a white hole in universe B. for all intents and purposes the inside of a black hole is not something you can pass through, it just accumulates stuff and due to gravity that ‘stuff’ is crushed and merged into the black hole. so ruling out that black holes are universal bridges (same reason wormholes could exist but don’t), a white hole no longer has reason to exist.

2. even then, for a white hole to spit out radiation and particles it would need to be constantly spitting out energy in such amounts that particles can spontaneously be created. if we are talking about “opposite of a black hole” then the amount of energy coming out needs to approximate the amount of energy falling into a black hole of similar size. so then white holes ‘grow’ by evaporation and ‘shrink’ by ejecting energy in all directions. no matter how you try to think about it a true opposite of a black hole, in a thermodynamical sense, is ludicrous.

3. ok, so ignoring why a white hole can exist or where it gets its energy from, my favorite argument comes up… what happens to all the energy and matter that the white hole spits out? without a sufficient escape velocity all the energy and matter that a white hole spits out would be gravitationally attracted to itself, and inevitably (so long as the white hole continues to spit out matter/energy) will collapse to form a black hole. providing ‘sufficient’ escape velocity to avoid this scenario would rob the white hole of even more energy still…

given the above you would have to conclude that the only way a white hole can exist is a black hole operating in reverse time. quite possibly an ‘antimatter black hole’ would fit this category (arguably antimatter and time-reversed matter have a lot in common, indeed in QM the distinction is often moot for single particles)

13. Donald Pennino says:

It should be obvious to everyone that white holes exit. The Big bang was nothing more then matter from another universe spewing into our “known” universe. Black holes spew the same crap back into another. Proof there is at least one other universe(probably many more). Our universe is not “infinite” but has finite volume made of some type of fabric with barriers. This answers most of physics question. Just open your mind up and don’t get pulled into a mathematicians or philosophers rule minded game. Heaven, hell, multi-dimensions, ghosts, time portals, etc . It’s all the same thing that we have given different names for our lack of understanding of how it all works.

14. casey says:

is this saying that a white hole existed before our universe and that possibly they exist on the other side of blackholes so therefore they are not in our universe and do not exist or they just don’t exist at all