The general theory of relativity was published by the physics genius more than a century ago, to refine Isaac Newton’s law of universal gravitation.
Providing a unified description of gravity as a geometric property of space and time, or spacetime, this model is still currently used by scientists as an explanation of gravitation in modern physics.
Einstein’s theory has important astrophysical implications as it alludes to the existence of black holes – cosmic phenomenons in which space and time are distorted in such a way that nothing, not even light, can escape.
At the center of a black hole, as described by general relativity, may lie a gravitational singularity, a region where the spacetime curvature becomes infinite.
But while mathematics says a singularity is possible, nature apparently proves these do not exist, Discovery Channel’s ‘How The Universe Works’ exposed.
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’.”
Astronomer Phil Plait explained why some experts have an issue with using 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.”
Theoretical physics Lawrence Krauss then explained why some are questioning 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 fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles.
Leading astronomer and assistant director for Science Communication at NASA’s Goddard Space Flight Centre, Michelle Thaller, explained why it is key 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.”
The smallest unit in the universe is what is known as a Planck Length to physicists.
But if there is a universal limit on the smallest size, then something infinitely small cannot exist, according to some scientists.
Quantum mechanics expert Sean Carroll explained: “If infinity doesn’t exist, then singularities don’t exist.
“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.”
This has led scientists to invent the theory of the Planck Star.
Passing one in space would look like a black hole, but without a point of singularity at its core.
The star is just like a black hole, but it obeys the rules of quantum mechanics.
Physicist Max Tegmark detailed the new theory that has been proposed.
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.”