The physics genius put out the general theory of relativity more than a hundred years ago to improve Isaac Newton’s law of universal gravitation. This model is still used by scientists to explain gravity in modern physics. It gives a unified description of gravity as a geometric property of space and time, or spacetime.

Einstein’s theory has important astrophysical implications because it hints at the existence of black holes, which are places in the universe where space and time are so warped that nothing, not even light, can get out.

General relativity says that a gravitational singularity, a place where spacetime curves indefinitely, could be at the center of a black hole.

But the show ** “How the Universe Works”** on Discovery Channel showed that even though math says a singularity is possible, nature seems to show that they don’t exist.

The series explained: “When a giant dying star collapses, the mass of the star falls in and keeps falling in crushing down into an infinitely small point.

“This is called the singularity.”

But physicist Max Tegmark believes the “

singularity” is “just a fancy way of saying ‘we have no idea what is happening here’.”

Phil Plait, an astrophysicist, explained why some experts don’t like this theory.

He said: “The way our physics describes black holes when they form is you’re taking a finite amount of mass and you’re collapsing it down.

“Its volume should shrink all the way down to zero, but that means it has infinite density and infinite gravity.

“That doesn’t make sense.”

Lawrence Krauss then explained why some people have doubts about Einstein’s theory.

He added: “If you make a prediction and the answer is infinite, then it tells you that there is something wrong with your prediction.

“We have never seen infinity in the universe.

“Maybe a black hole with an event horizon described by general relativity just isn’t the proper description of the physics.”

Quantum mechanics is a basic theory in physics that explains how atoms and subatomic particles behave from a physical point of view.

Michelle Thaller, a leading astronomer and the assistant director for Science Communication at NASA’s Goddard Space Flight Centre, explained why it is so important to the debate.

She said in 2018: “Have you ever thought about the term quantum mechanics and what those terms actually mean?

“Everything in the universe is broken up into tiny units and there is a basic unit of energy, time and space that cannot be divided any smaller.

“There is a limit to how small those things can be.”

A Planck Length is what physicists call the smallest unit in the universe.

But some scientists say that if the smallest size has a limit everywhere, then something that is infinitely small can’t exist.

Sean Carroll, an expert in quantum mechanics, said, “If infinity doesn’t exist, then neither do singularities.

“And if singularities don’t exist, then Einstein’s theory of General Relativity is not correct.

“The simplest thing we can do is change some equations, change his theory of gravity.

“Let’s invent what we would call exotic speculative physics.”

Because of this, scientists came up with the idea of the Planck Star.

If you were to pass one in space, it would look like a black hole, but it wouldn’t have a singularity at its center.

The star is just like a black hole, but it follows the rules of quantum mechanics.

Max Tegmark, a physicist, explained the new idea that has been put forward.

He said: “Maybe things can be collapsed down to less than the Planck Length, or maybe you get stuck with a Planck-sized nugget.

“It stabilizes everything, keeps everything finite.

“The reason why there are so many alternatives to black holes is because you can write down a gazillion different postulated mysterious new kinds of matter and say ‘this exists, so maybe that explains the data’.

“The problem is there is no evidence that any of that kind of stuff exists.”