To solve the mysteries of black holes, a man should venture into one.
However, there is a rather complicated catch: a man can do this only if the black hole is supermassive and isolated and if the person entering the black hole does not expect to report the discoveries to anyone in the entire Universe.
We are both physicists studying black holes, albeit from a very safe distance. Black holes are among the most abundant astrophysical objects in our universe.
These interesting objects seem to be an essential ingredient in the evolution of the Universe, from the Big Bang to the present. 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 lying down. (Leo Rodriguez / Shanshan Rodriguez / CC BY-ND)
Two types of black holes
The universe is full of a vast zoo with different types of black holes.
They can vary in size and can be electrically charged, in the same way that atoms or protons are in atoms. Some black holes actually rotate. There are two types of black holes that are relevant to our discussion.
The first one does not rotate, it is electrically neutral – that is, it is not positively or negatively charged – and it has the mass of our Sun. The second type is a supermassive black hole, with a mass millions to billions of times greater than that of our Sun.
In addition to the difference in mass between these two types of black holes, what differentiates them is the distance from their center to the “event horizon” – a measure called radial distance.
A person who falls into a supermassive black hole would probably 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 up by the black hole and will disappear forever from our known Universe.
At the event horizon, the gravity of the black hole is so strong that no amount of mechanical force can exceed or counteract it. Even light, the fastest movement in our universe, cannot escape – hence the term “black hole”.
The radial dimension of the event horizon depends on the mass of the respective black hole and is essential for a person to survive falling into one. For a black hole with a mass of our Sun (a solar mass), the horizon of events will have a radius of just under 3 miles (3.2 kilometers).
A person approaching the horizon of events of a black hole the size of the Sun. (Leo and Shanshan Rodriguez / CC BY-ND)
Instead, the supermassive black hole in the center of our Milky Way galaxy has a mass of about 4 million solar masses and has a horizon of events with a radius of 7.3 million miles or 17 solar rays.
Thus, someone who falls into a stellar-sized black hole will get much, much closer to the center of the black hole before crossing the event horizon, as opposed to falling into a supermassive black hole.
This implies, due to the proximity of the center of the black hole, that the attraction of the black hole on a person will differ by a factor of 1,000 billion times between the head and finger, depending on which leads the free fall.
In other words, if the person first falls off their feet, as they approach the horizon of the events of a black star hole, the gravitational pull on their feet will be exponentially higher compared to towing the black hole on their head.
The person would experience spaghetti and most likely will not survive being stretched into a long, thin, noodle-like shape.
Now, a person falling into a supermassive black hole would reach the horizon of events far beyond the central source of gravitational attraction, which means that the difference in gravitational attraction between the head and toe is almost zero.
Thus, the person would pass through the horizon of events unaffected, would not be stretched in a long and thin noodle, would 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 disks of material, mainly comprising gas and dust or other objects such as stars and planets that got too close to the horizon and fell into the black hole.
These disks are called accumulation disks and are very hot and turbulent. They are certainly not hospitable and would make the journey into the black hole extremely dangerous.
To enter safely, you should find a supermassive black hole that is completely insulated and does not feed on surrounding material, gas, or even stars.
Now, if a person found an isolated supermassive black hole suitable for scientific study and decided to venture, everything he observed or measured inside the black hole would be limited to the events of the black hole.
Given that nothing can escape gravitational attraction beyond the horizon of events, the falling person could not send any information about his discoveries beyond this horizon. Their journey and discoveries would be lost to the rest of the entire Universe of all time. 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 Conversation under a Creative Commons license. Read the original article.