Black holes

Black holes are the only ones that can trap light, as their gravitational force is powerful. They would form from ultra-concentrated material that destroys everything in its path. Here are some amazing facts about these black giants.

1 - Black holes do not aspire matter, they attract it:

No form of matter can emerge from a black hole once trapped inside, not even light. That's why he's invisible. However, it does not really attract matter: it makes it gravitate around it, as our sun does. It is only once inside that one reaches the point of no return.

2 - Einstein did not discover the black holes:

It was the astrophysicist Karl Schwarzschild who solved Einstein's equations on the formation of black holes in 1915. From this appears the "Schwarzschild radius", which measures how much matter must be compressed to form a black hole.

3 - The black holes "spaghettif" everything that happens in their center:

Even if they do not attract everything around them, once an object has "fallen" inside, the gravity is such that it stretches the material in a spectacular way. Let us take the example of a human: the feet are closer to the earth's core than the rest of the body, and are therefore more attracted by gravity. The same thing happens in a black hole, but in much more powerful, which explains this "spaghettification": the more the body sinks into the black hole, the faster it goes, the more it is stretched.

4 - Black holes distort the space around them:

As if a ball were placed on a fabric stretched over the void, the latter would sink under the weight of the ball. And the heavier the ball, the deeper it sinks and the fabric is distended. It is the same thing happening with black holes in space: the bigger the black hole, the more the space around it is deformed, and nothing has enough energy to get out of it, not Even the light.

5 - A source of energy titanic:

Everything on the horizon of events (see diagram) gravitates so fast that it produces heat at billions of degrees, which turns matter into energy, so-called radiation of the black body .

6 - A black hole is right in the middle of our galaxy:

Scientists believe that a black hole is in the center of each galaxy, including the Milky Way. It would serve as an anchor, which would allow the galaxies to remain in place in space. The black hole in the center of the Milky Way, Sagittarius A, 30,000 light years away, is 4 million times more massive than our Sun.

7 - Time slowed down inside the black hole:

If one travels at the speed of light from a point A, time passes much faster. But in returning to this point A, time has suffered no effect; The faster you move, the slower the time. On the horizon of events, a body moves at such a speed that time slows down for it.

8 - Black holes evaporate:

Nothing is eternal, not even a black hole: what the physicist Stephen Hawking thinks in 1974. The phenomenon, called the radiation of Hawking, indicates that the mass of the black hole disperses in space, That there is nothing left.

9 - Anything can become a black hole:

Provided that the thing in question is extremely compressed and dense, which would give it a strong gravitational field. And it is this gravitational field that gives its power to the black hole and aspires all that is in its center. In theory. If we shrink our Sun until it has a diameter of 6 km, it could very well turn into a black hole. But for now, we really know only one way black holes are formed: the destruction of a star that would be 20 times more massive than the sun.

10 - Black holes could generate new universes:

The conditions in our universe are ideal for creating life, and if we were to change a single characteristic, life would not exist at all. This is why scientists are led to think that a black hole could give rise to new universes, so much it defies the laws of physics.

Will we soon be able to photograph the horizon of a black hole?

Black holes are among the most fascinating objects in the universe, but despite the fact that they hide in the center of most galaxies, no one has ever been able to see them, To photograph. But this could be about to change.

The Event Horizon telescope is expected to enter service in April. It is a global network of antennas with receivers installed at the South Pole, the United States, Chile and the French Alps, which will try to "see" for the first time the supermassive black hole called Sagittarius A *, nested in the center Of our galaxy, the Milky Way. This is enough to test Einstein's theory of general relativity as never before.

The Event Horizon telescope operates using very long base interferometry (VLBI) at short wavelengths, which means that the receiver network will concentrate on the radio waves emitted by a particular object in space. For the black hole, they will concentrate on the radio waves with a wavelength of 1.3 mm (230 GHz), what to maximize the chances of piercing the clouds of gas and dust blocking us the view of the hole black. And because all these antennas will be oriented in the same direction, the resolution of the telescope should reach 50 microarcseconds. To put this into perspective, imagine that you are able to see a grapefruit on the surface of the moon.

We have never directly observed Sagittarius A *, but researchers know it exists because of its gravitational influence on the surrounding stars. Based on the behavior of these nearby stars, researchers predict a black hole about four million times more massive than our Sun, but with a horizon diameter of events of only 20,000,000 kilometers. Located at a distance of about 26,000 light years from the Earth, observing the black hole that directly governs the center of our galaxy is no small goal. The Event Horizon telescope will aim to observe the immediate environment around the black hole, but it should be able to get sufficient resolution to see the black hole itself.

But then, what would our black hole look like? Probably to a shiny ring moving around a dark spot. Light is emitted by particles of gas and dust which are accelerated at speeds close to that of light just before they are torn and consumed by the black hole. But if Einstein was right, then we should see more than one crescent of light than a ring because a dramatic Doppler effect will illuminate the material moving to the Earth, making it much brighter.

Mysterious radio impulses from a black hole.

Extremely fast and occurring in random places in the universe, rapid radio bursts are extremely difficult to record. An international team has just recorded a radio pulse from a black hole.

Fast Radio Burst (FRB), or fast radio bursts, occur in large numbers every day in the confines of the universe, but these last only a few milliseconds, making them extremely difficult to record. To date, only about 20 FRB have been registered by scientists, who still do not explain their origin.

Last February, the 64-meter Parkes radio telescope in Australia managed to locate one. An international collaboration of astronomers then looked at the phenomenon, and thanks to the Japanese Subaru telescope, located in Mauna Kea in Hawaii, these astronomers were able to locate the source, a black hole, as well as the source galaxy called Arp 220 , An elliptical galaxy located at about 6 billion light years.

The FRB signal, then nicknamed "FRB 150418", was used to test a computer model that could have elucidated the puzzle of the origin of these rapid radio bursts. Astronomers then realized that supermassive black holes consistently produce this type of emissions, but that it may not be FRB itself. The material, like the stars, dust and gas, which find themselves trapped in the gravitational well of the black hole forms a hot accretion disk. These black holes thus constantly emit powerful jets of relativistic material ejected from the poles of the black hole, a mechanism that produces many radio waves of this type.

It therefore seems that the origin of the mystery of the FRB is as mysterious as it was in 2007 when the first FRB was archived. "We do not even know if they come from within our galaxy or are extragalactic," says Edo Berger, an American astronomer who participated in the study.

What would happen if the Earth were sucked into a black hole?

Black holes have long been a great source of excitement and intrigue. And now that the gravitational waves have been discovered, the interest in everything concerning black holes will surely develop. A scientist presented several scenarios in which he described how black holes could theoretically affect humans and the Earth itself.

The supermassive black holes are very dense areas in the center of galaxies with masses that can be billions of times greater than that of the sun. They act as intense sources of gravity that suck up the dust and gas surrounding them. Their intense gravitational attraction is probably the same as that of the stars around which the galaxies revolve in orbit, but we still have difficulty understanding how these black holes form.

One of the theories of astronomers is that they can form when a large gas cloud up to 100,000 times wider than the sun collapses, turning into a black hole at the same time. Many of these black holes merge to form much larger supermassive black holes. Alternatively, a supermassive black hole could come from a giant star, about 100 times the mass of the sun, which turns to the end of its life after the exhaustion of the gas that serves as fuel for it, Collapse of the star, transforming it into a black hole.

What would happen if the Earth fell into a black hole? An expert describes the three scenarios that could befall our planet in this case:

As we approached our planet, the black hole would encounter the Oort cloud from which it would project the stars in its direction. Some could violently touch the Earth already causing some small cataclysms. His accretion disk would form as he began to devour the planets. Arrived near the Earth, it is our atmosphere that would be progressively torn away followed by the entire planet. In this period of time, earthquakes, tidal waves and super-volcanoes would probably have already swept away any form of life.

If by a miracle we were still alive, in a kind of capsule for example, then the journey to the black hole would begin.

1 - Spaghettizing: If one approaches too close to a black hole, one will then stretch, just like spaghetti, the time will also gradually slow down.

2 - Radiation: Long before we were spaghettized, the power of this radiation could freeze us.

3 - Transformation into a hologram: Another theory is that any object composed of matter that touches a black hole becomes an imperfect copy of itself, and continues to exist as before. This theory suggests that there is a surface in another dimension, perhaps a fourth or more, that we can not see.

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