Dear Darwin and Rubal,
Before I read your question, I had never heard of a white hole.
So, I scampered over to my friend Vivienne Baldassare to find out more. She’s an astrophysicist at Washington State University.
She told me that, so far, white holes are just an idea. It’s what happens if you take math about black holes and work it backwards.
“White holes are really the mathematical inverse of a black hole,” Baldassare said. “But we have no reason to think they exist right now.”
A black hole is an area in space that has gobs of gravity.
We’re familiar with the gravity we experience on Earth. That’s the force that holds everything—our bodies, our buildings, even the oceans—on Earth. It’s why we don’t float off into space. That gravity happens because our planet is super big. All the matter that makes the Earth pulls on our bodies.
A black hole is made of matter, too. It’s crammed together into a super small space. Scientists say it’s dense—super tightly packed together.
The pull of gravity in a black hole is so strong that nothing can escape—not even light. Something inside a black hole would need to travel faster than the speed of light to get away. Since nothing can move that fast, nothing can ever get out.
This is the first photo ever taken of a black hole. It’s at the center of the M87 galaxy—about 55 million light years from Earth. ©Event Horizon Telescope Collaboration
A white hole would be the opposite. It would be a region in space where nothing could ever go fast enough to get in. It might be a one-way space fountain that spews matter out into space.
A black hole forms when a massive star dies. Its core collapses and makes an explosion called a supernova. Then all that remaining matter crushes together into a dense point.
It’s unclear what natural event could cause a white hole. To make it work mathematically on paper, you run time backwards. It’s hard to imagine that happening in real life.
But if it did, there could be incredible implications.
“Some theories suggest that maybe white holes are on the other side of black holes in another universe,” Baldassare said. “So, we’d have a black hole in our universe, and it would lead to a white hole in another universe—but it’s all very theoretical.”
If that sounds like a fun way to travel between universes, I’m sorry to say that nobody could survive a trip like that. They’d be squeezed into noodles by the gravity in the black hole—called spaghettification—long before they popped out through the white hole.
But don’t completely give up on finding white holes.
People have been thinking about space objects like black holes since way back in the 1600s. That’s wild because we didn’t confirm black holes were real until 1971. The first ever photo of a black hole happened in 2019.
And those are super big or super common objects.
“There are super massive black holes that are millions and billions of times the mass of the sun,” Baldassare said. “And then there are smaller black holes all over the place. Every galaxy has millions of them.”
Maybe it’ll just take some time to get our paws on a matter-spewing space fountain.
Sincerely,
Dr. Universe