There is a way for humans to ‘safely’ enter a black hole, physicists say

To solve the mysteries of black holes, a human would simply have to venture into them.

However, there is a rather complicated catch: a human can only do this if the respective black hole is supermassive and isolated, and if the person who enters the black hole does not expect to report the results to anyone in it. entire universe.

We are both physicists who study black holes, albeit at a very safe distance. Black holes are among the most abundant astrophysical objects in our Universe.

These intriguing objects seem to be an essential ingredient in the evolution of the Universe, from the Big Bang to the present day. They probably had an impact on the formation of human life in our own galaxy.

A person who falls into a black hole and is stretched. (Leo Rodriguez / Shanshan Rodriguez / CC BY-ND)

Two types of black holes

The Universe is littered with a vast zoo of different types of black holes.

They can vary in size and be electrically charged, in the same way that electrons or protons are in atoms. Some black holes are actually spinning. There are two types of black holes which are relevant to our discussion.

The former does not rotate, is electrically neutral – that is, not positively or negatively charged – and has the mass of our Sun. The second type is a supermassive black hole, with a mass of millions or even billions of times that of our Sun.

Besides the difference in mass between these two types of black holes, what also differentiates them is the distance from their center to their “event horizon” – a measure called radial distance.

A person falling into a supermassive black hole would likely survive. (Leo and Shanshan Rodriguez / CC BY-ND)

The event horizon of a black hole is the point of no return. Anything that passes this point will be swallowed by the black hole and will disappear forever from our known universe.

On the event horizon, the black hole’s gravity is so powerful that no mechanical force can overcome or thwart it. Even light, the fastest moving thing in our Universe, cannot escape – hence the term “black hole”.

The radial size of the event horizon depends on the mass of the respective black hole and is essential for a person to survive by falling into one. For a black hole with a mass of our Sun (a solar mass), the event horizon will have a radius of just under 3.2 kilometers.

A person approaching the event horizon of a sun-sized black hole. (Leo and Shanshan Rodriguez / CC BY-ND)

The supermassive black hole at the center of our Milky Way galaxy, on the other hand, has a mass of about 4 million solar masses, and it has an event horizon with a radius of 7.3 million miles or 17 rays. solar.

So someone falling into a stellar-sized black hole will get much, much closer to the center of the black hole before passing the event horizon, instead of falling into a supermassive black hole.

This implies, due to the proximity to the center of the black hole, that the attraction of the black hole on a person will differ by a factor of 1000 billion times between the head and the toes, depending on which one is leading the free fall .

In other words, if the person falls with their feet first, as they approach the event horizon of a stellar mass black hole, the gravitational pull on their feet will be exponentially greater than the pulling the black hole on his head.

The person would undergo spaghettification and likely not survive a long, thin noodle-like shape.

Now, a person falling into a supermassive black hole would reach the event horizon much further away from the central source of gravitational pull, meaning the difference in gravitational pull between the head and toes is almost zero.

Thus, the person would cross the event horizon unaffected, not be stretched into a long, thin noodle, survive and float painlessly beyond the horizon of the black hole.

Other considerations

Most of the black holes we observe in the Universe are surrounded by very hot discs of matter, mostly comprising gas and dust or other objects like stars and planets that have come too close to the horizon and fell into the black hole.

These disks are called accretion disks and are very hot and turbulent. They are certainly not hospitable and would make the trip to the black hole extremely dangerous.

To get into it safely, you need to find a supermassive black hole that is completely isolated and does not feed on surrounding materials, gas, or even stars.

Now, if a person discovered an isolated supermassive black hole suitable for scientific study and decided to venture into it, anything that was observed or measured inside the black hole would be confined to the black hole’s event horizon.

Keeping in mind that nothing can escape the gravitational pull beyond the event horizon, the falling person would not be able to send information about their findings beyond that horizon. Their journey and their discoveries would be lost to the rest of the entire universe forever. But they would enjoy the adventure, as long as they survived… maybe….

Leo Rodriguez, Assistant Professor of Physics, Grinnell College and Shanshan Rodriguez, Assistant Professor of Physics, Grinnell College.

This article is republished from The Conversation under a Creative Commons license. Read the original article.