In a new study, the Czech theorist and his colleagues concluded that a black hole could be a cold sun for planets. Scientists believe that planets orbiting the black hole can support life.
According to the second law of thermodynamics, life requires a temperature difference, which is a source of useful energy. For us, this is the Sun, which is much hotter than the surrounding space, but in other parts of the cosmos, everything can be exactly the opposite: when the star is cold, and its environment is warm.
Tomáš Opatrný of Palacky University in Olomouc, Czech Republic, simulated what would happen to a planet with a cold sun and hot skies.
Recall that some black holes have a temperature near absolute zero temperature (0 K), while its environment is much "warmer" - its temperature is about minus 270 degrees Celsius, that is, about 3 K (due to relict radiation - the heat left after Big Bang). This is the very necessary difference. That is, black holes can act as cold suns.
Opatrny and his colleagues concluded that at this temperature difference, a planet the size of Earth orbiting a black hole that looks the size of our sun would receive about 900 watts of energy. Note that black holes are sometimes one of the brightest objects in the sky: heated particles of matter and gas fall on it under the influence of powerful gravity and glow in the X-ray range.
This is enough for a complex life to exist, at least for a short period of time (that is, for the development of civilization, this is still not enough). Even an old black hole, which has "eaten up" all the crumbs of matter in its vicinity, is constantly falling on some matter. This means that such a “cold sun” will not stay cool for a long time.
Let's add that the early Universe was even warmer. 15 million years after the Big Bang, according to the calculations of physicists, its temperature was 27 kelvin. That is, water could exist in the early Universe, and a planet that lived in the vicinity of a relatively cool black hole could receive 130 gigawatts of energy at all (this is about a millionth of what the Sun gives the Earth, and still quite a lot). Even a complex life could have formed, but too little time has passed since the Big Bang for it to develop.
Opatrny believes that a black hole called Gargantua, shown in the science fiction movie Interstellar, could organize enough energy to support complex life, albeit for a short time (in the context of the entire universe).
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However, one important circumstance must be taken into account. The gravitational pull of a black hole slows down time on Miller's planet (one hour there is equivalent to seven Earth years). This means that the relic radiation in its vicinity is much higher in energy (slowing down increases the frequency of light). That is, the temperature of this world should have reached about 900 degrees Celsius. Accordingly, the huge tidal waves of this world should not have been made of water, but rather molten aluminum!
Scientists in their work also suggested that when, after 100 billion years, all the stars of the Universe are burned out, life can move closer to black holes, which will heat up the surrounding area with the light generated from the matter falling on them.
Opatrna's scientific work was published on the arxiv.org website.