#122 What are wormholes?

I learned this today. A wormhole is a hypothetical tunnel that would connect two separate points in space.

Wormholes are hypothetical and have obviously never been discovered. They were first theorized in 1916. Karl Schwarzschild, a German physicist and astronomer started looking into Einstein’s field equations. These are the equations that Einstein used in his general theory of relativity to relate the geometry of spacetime to the distribution of matter within it. Schwarzschild wrote two papers on these equations, but then he died at the age of 42. Ludwig Flamm, an Austrian physicist, was looking at Schwarzschild’s calculations and he realized another solution was possible. He realized that a “white hole”, the technical opposite of a black hole, was possible. A black hole sucks matter in and a white hole spews it out. He theorized that perhaps the black hole and the white hole were connected in some way.

These ended up being called Schwarzschild wormholes in honor of him, but it was found that they would collapse almost as soon as they formed.

In 1935, Einstein and physicist Nathan Rosen came up with the concept of a “bridge”. They called it an Einstein-Rosen bridge. They built on the work of Schwarzschild and theorized that every black hole would be paired with a white hole. Nothing would be able to escape once it passed the event horizon in a black hole and nothing would be able to pass the event horizon into a white hole.

However, there are two problems with this idea.

Firstly, because nothing can pass the event horizon of the white hole, the energy would increase to infinity. A single particle passing through from the other side would have so much energy that the white hole would explode.

Secondly, if this was a viable way of traveling from one point in space to another, there would be no way of going back. Matter can only ever pass from the black hole to the white hole.

The singularities of both the black hole and the white hole would be connected in some way. The singularity is the point where matter is compressed down until it is infinitely small. All physics would break down at this point. Logically, you can’t have something that is infinitely small, just like you can’t have infinite energy in a white hole. If the black hole becomes a white hole, it would be some kind of answer. If it crushes down and then expands back up.

As an interesting aside, one theory on white holes is that they are responsible for the big bang and the start of the universe. Because so much energy is accrued when matter goes from a black hole to a white hole, every time a white hole forms it explodes and forms a new universe. If that is true, then new universes could be forming all over the place.

White holes are theoretical and have never been found. Also, if they did exist, they would probably be microscopic. They could be 10^-33 centimeters.

If they were ever discovered and a way of traveling through them could be found, there would have to be a way to make them more stable. Because the energy put into a white hole rapidly approaches infinity, there needs to be a way to remove that energy. There would have to be an exotic type of matter that contains negative energy and negative pressure.

Exotic matter has never been seen but it is theorized to exist. It would be seen in the behavior of some vacuum states in the quantum field.

Wormholes are just theory and many physicists doubt that they would be possible, but, if they were possible and could be maintained for long enough that we could travel through them, the benefits would be enormous.

The main benefit would be faster than light travel. There is nothing with mass that can travel faster than light. Even if we could travel at light speed, it would take us 4.35 years to reach the closest star, Alpha Centauri A. It would take us 105,700 years to cross the Milky Way Galaxy. It would take us 2.537 million years to reach the Andromeda Galaxy. And this is if we could travel at light speed, which it isn’t possible to do. However, if we could control a wormhole and have the black hole entrance near to us and the white hole exit in the Andromeda Galaxy, we could get there in as long as it took to traverse the wormhole without ever exceeding the speed of light and breaking the laws of physics. Well, apart from the laws of physics that say you can’t travel through a wormhole. I wonder if one day people will be able to do this. It seems like the only way we could ever explore the universe in any significant way.

So, a wormhole is a hypothetical tunnel between a black hole that sucks in matter and a white hole that sprays it out. And that is what I learned today.

Photo By https://www.space.com/20881-wormholes.html

Sources

https://physics.aps.org/story/v15/st11

https://www.livescience.com/what-are-wormholes

https://www.livescience.com/wormholes-may-be-stable-after-all

https://en.wikipedia.org/wiki/Wormhole

https://www.space.com/20881-wormholes.html

https://www.space.com/white-holes.html

https://en.wikipedia.org/wiki/Ludwig_Flamm

https://en.wikipedia.org/wiki/Schwarzschild_metric

https://en.wikipedia.org/wiki/Karl_Schwarzschild

https://en.wikipedia.org/wiki/Einstein_field_equations