Man must undertake just one venture to solve the mysteries of black holes.
However, there is an increasingly complex catch: a human can only do so if the associated black hole is supermassive and isolated, and if the person entering the black hole does not expect to report the findings to anyone in the entire universe.
We are both physicists who study black holes, although they are from a very safe distance. Black holes are the most abundant celestial body in our universe.
These tricky objects are an essential component in the development of the universe from the Big Bang to the present day. They probably had an influence on the creation of human life in our own galaxy.
Two types of black holes
The universe is awash with huge zoos of various types of black holes.
They can vary in size and be electrically charged, similarly to electrons or protons in atoms. Some black holes actually spin. There are two types of black holes that are relevant to our discussion.
The first does not rotate, is electrically neutral – that is, not positively or negatively charged – and is the mass of our Sun. The second type is a supermassive black hole, whose mass is more than millions of billion times that of our Sun.
In addition to the large-scale differences between these two types of black holes, what differentiates them is the distance from their center to their “event horizon” – a measure called the radial distance.
The black hole’s event horizon is the point of no return. Whatever passes through this point will be swallowed up by the black hole and disappear from our known universe forever.
At the event horizon, the gravity of a black hole is so powerful that no mechanical force can cross it or counteract 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 corresponding black hole and is important to avoid a person falling into one. For a black hole with a mass of our Sun (a solar mass), the radius of the event horizon would be just under 2 miles (3.2 kilometers).
In contrast the mass of a supermassive black hole in the center of our Milky Way galaxy is about 4 million solar masses, and has an event horizon with a radius of 7.3 million miles, or 17 solar radii.
Thus, by falling into a stellar-shaped black hole, one would get very close to the center of the black hole before crossing the event horizon, as opposed to falling into a supermassive black hole.
This means, due to the proximity of the center of the black hole, that the stretch of a black hole on a person will vary between the head and toe by a factor of 1,000 billion times, depending on which free fall occurs.
In other words, if the person is falling feet first, as they approach the event horizon of a stellar mass black hole, the gravitational pull on their feet will be exponentially larger than the tug of the black hole on their head.
The person will experience spagotification, and most likely will not survive a long, thin noodle-like shape.
Now, a person falling into a supermassive black hole will reach far from the central source of the gravitational pull to the event horizon, meaning that the difference in gravitational stretch between the head and toe is almost zero.
Thus, the person will pass through the unaffected event horizon, will not be able to survive in the long, thin noodle between the black hole horizons and can swim without pain.
Most black holes that we see in the universe are surrounded by very hot material, mostly consisting of gas and dust or other objects such as stars and planets that reached too close to the horizon and fell into a black hole.
These disks are called accretion disks and are very hot and turbulent. They are certainly not hospitable and traveling in a black hole would be extremely dangerous.
To enter one safely, you will need to find a supermassive black hole that is completely isolated and does not feed on surrounding material, gas, or even wires.
Now, if a person found a separate supermassive black hole suitable for scientific study and confined it to the inner horizon of a black hole, the interior of the black hole was observed or measured.
Keeping in mind that no gravitational stretch beyond the event horizon can survive, the falling person will not be able to send any information about their findings beyond this horizon. His journey and conclusions will be lost to the entire universe for all time. But they will enjoy the adventure, as long as they live… maybe….
Leo Rodriguez, Assistant Professor of Physics, Grinnell College and Shanshan Rodriguez, Assistant Professor of Physics, Grinnell College.
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