At the beginning of the new academic year, we decided to devote the first material from the series "Scientists against myths" to the mystery of space, namely, black holes. Earlier NGS. OMSK wrote that astronomy was returned to the high school curriculum. We asked our questions to Vladimir Dmitriev, associate professor of the Department of Physics and Methods of Teaching Physics of the OmSPU. He told whether it is possible to "dive" into a black hole, what a person will notice there, whether it can be seen with the naked eye and whether it is capable of being a portal to another dimension.
Myth # 1: Black holes are not visible
- It all depends on what we want to see. This is not an ordinary object we are used to, like a table. It does not reflect light. Strictly speaking, a black hole is a piece of space and time, whose attraction is so great that nothing can fly out of there. Including light. The volume of a black hole tends to zero, and the density tends to infinity. That is, it is not an object, but a certain area. Any black hole has a so-called "event horizon". Anything below the event horizon is invisible. Everything above is visible.
So, returning to the question, a black hole never exists by itself. There is always substance around it. And this substance begins to fall onto the black hole. As it falls, it accelerates. As it accelerates, it twists and forms an accretion disk. This is a disc that looks more like a donut. As matter accelerates, collides, it heats up and ionizes. It turns out a bunch of charged particles that move in a circle. The disc is lit. Thus, the brightest objects in the universe are obtained - quasars. This is what we really see. That is, we see not the black hole itself, but the matter around it. And the greater the mass, the brighter the accretion disk glows.
As long as there is matter around the black hole, as long as it has something to "reach", it is a quasar. The substance ran out, and she ceased to be visible. All the quasars closest to us now visible are at a distance of 6 billion light years. That is, now they may have gone out, but for now you can see them in the sky. To humans, they look like ordinary stars.
Myth # 2: Black holes are constantly growing and will someday collect the entire universe
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- Black holes are really getting bigger. The mass increased - the radius of attraction increased. Thermodynamics states that the radius of a black hole cannot decrease. But quantum mechanics says it can. Which of these sciences is right is not yet clear.
According to quantum theory, black holes should evaporate - emit photons. This is a very slow process, but it is there. The more mass, the slower it radiates. The smaller, the brighter, brighter and brighter it glows. In the last seconds of the hole's life, there will be a flash. This will happen only when the hole has no one to "reach". In theory, this is possible. The entire universe will not be collected into one black hole for one simple reason - they are too far from each other.
Myth # 3: Can you fly through a black hole
- If the original body and, accordingly, the black hole rotates, then an ergosphere is formed around the body of the black hole up to three gravitational radii of the hole itself. It cannot have stable orbits. If a single body enters the ergosphere, it will most likely be torn apart.
What happens to an object when it falls? Let's take a man. It passes through the ergosphere and each … each part of it acquires its own trajectory. Here is the movie "Interstellar" … (Laughs.) As astronomers say, the substance from which you are made, of course, will get inside the black hole, but will this substance be you …
Myth # 4: Black holes are portals or "wormholes"
- The point is that there are two black holes and they are somehow connected. Yes, there is such a theory. As if the substance falls into a tunnel and flies, flies, flies. It's hard to say, but unlikely. Nature does not tolerate complex structures, and this one is very complex, in which it moved a little, and it broke. For such a tunnel, not only gravity is needed, which will tighten, but also anti-gravity, which will hold the walls. That is, you have to fold the dark substance into the tube and put it around the substance. In nature, only the simplest designs remain.
That is, according to theory, they can arise, but will immediately collapse. Why then are they at all? Moreover, even if the black holes are connected, they can only tighten. You will not return back to our universe - a one-way road.