- 3333 - BLACKHOLES - Einstein’s theories proven right? A new physics breakthrough shows how Einstein's theory of general relativity continues to hold up, even for "balding" blackholes. Blackholes are regions of spacetime where gravity's pull is so strong that nothing, not even light, can escape from being dragged in and "eaten."
---------------- 3333 - BLACKHOLES - Einstein’s theories proven right?
- Einstein's theory of general relativity predicted the existence of blackholes and that, no matter what such an object "eats," blackholes are characterized only by their mass, spin and electrical charge.
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- But there has been a lingering snag to this theorem: “magnetic fields“. For the theorem to hold true, "eating" material shouldn't alter a blackhole's primary characteristics. But while blackholes can be "born" with strong magnetic fields, they can also gain them by "eating" certain material and clouds of plasma can sustain these magnetic fields around a blackhole.
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- Researchers found that magnetic fields around blackholes can evolve. Their simulation showed that magnetic field lines around the blackhole would quickly break apart and reconnect. This phenomenon created pockets of plasma, energized by the magnetic field, that would bubble up and either be ejected out into space or swallowed up by the blackhole.
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- Einstein (1879-1955) is one of the most famous scientists of all time. His theory of special relativity changed the way we think about space and time and established a universal speed limit of the speed of light.
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- At the age of 26, his theory of special relativity, was so-called because it deals with relative motion in the special case where gravitational forces are neglected. This was one of the greatest scientific revolutions in history, completely changing the way physicists think about space and time.
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- In effect, Einstein merged these into a single space-time continuum. One reason we think of space and time as being completely separate is because we measure them in different units, such as miles and seconds.
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- Einstein showed how they are actually interchangeable, linked to each other through the speed of light, 186,000 miles per second (300,000 kilometers per second). Perhaps the most famous consequence of special relativity is that nothing can travel faster than light.
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- But it also means that things start to behave very oddly as the speed of light is approached. If you could see a spaceship that was traveling at 80% the speed of light, it would look 40% shorter than when it appeared at rest.
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- And if you could see inside, everything would appear to move in slow motion, with a clock taking 100 seconds to tick through a minute. This means the spaceship's crew would actually age more slowly the faster they are traveling.
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------------------------------------ E = m * c^2
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- The equation expresses the equivalence of mass (m) and energy (E), two physical parameters previously believed to be completely separate. In traditional physics, mass measures the amount of matter contained in an object, whereas energy is a property the object has by virtue of its motion and the forces acting on it.
- Energy can exist in the complete absence of matter, for example in light or radio waves. However, Einstein's equation says that mass and energy are essentially the same thing, as long as you multiply the mass by c^2. The square of the speed of light is a very big number in order to ensure it ends up in the same units as energy.
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- This means that an object gains mass as it moves faster, simply because it's gaining energy. It also means that even an inert, stationary massive object has a huge amount of energy locked up inside it.
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- Lasers are an essential component of modern technology and are used in everything from barcode readers and laser pointers to holograms and fiber-optic communication. Although lasers are not commonly associated with Einstein, it was ultimately his work that made them possible.
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- The word laser, coined in 1959, stands for "light amplification by stimulated emission of radiation" and stimulated emission is a concept Einstein developed more than 40 years earlier.
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- In 1917, Einstein wrote a paper on the quantum theory of radiation that described, among other things, how a photon of light passing through a substance could stimulate the emission of further photons.
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- Einstein realized that the new photons travel in the same direction, and with the same frequency and phase, as the original photon. This results in a cascade effect as more and more virtually identical photons are produced.
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- People are still finding new applications for lasers today, from anti-drone weapons to super-fast computers.
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- Einstein finally succeeded in adding gravity into his theory of “general relativity“. He found that massive objects like planets and stars actually distort the fabric of space-time, and it's this distortion that produces the effects we perceive as “gravity“.
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- Einstein explained general relativity through a complex set of equations, which have an enormous range of applications. Perhaps the most famous solution to Einstein's equations came from Karl Schwarzschild's solution in 1916, a “blackhole“.
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- Even weirder is a solution that Einstein himself developed in 1935 in collaboration with Nathan Rosen, describing the possibility of shortcuts from one point in space-time to another. Originally dubbed Einstein-Rosen bridges, these are now known to all fans of science fiction by the more familiar name of “wormholes“.
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- One of the first things Einstein did with his equations of general relativity, back in 1915, was to apply them to the universe as a whole. But the answer that came out looked wrong to him. It implied that the fabric of space itself was in a state of continuous expansion, pulling galaxies along with it so the distances between them were constantly growing.
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- Common sense told Einstein that this couldn't be true, so he added something called the “cosmological constant” to his equations to produce a well-behaved, “static universe“.
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- But in 1929, Edwin Hubble's observations of other galaxies showed that the universe really is expanding, apparently in just the way that Einstein's original equations predicted. It looked like the end of the line for the cosmological constant, which Einstein later described as his biggest blunder.
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- That wasn't the end of the story, however. Based on more refined measurements of the expansion of the universe, we now know that it's speeding up, rather than slowing down as it ought to in the absence of a cosmological constant. So it looks as though Einstein's "blunder" wasn't such an error after all. Just change the plus sign to a minus sign then move it to the other side of the equation.
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- Einstein died in 1955, but his huge scientific legacy continues to make headlines even in the 21st century. This happened in a spectacular way in February 2016, with the announcement of the discovery of gravitational waves, yet another consequence of general relativity.
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- Gravitational waves are tiny ripples that propagate through the fabric of space-time. Using giant facilities such as the Laser Interferometer Gravitational-Wave Observatories (LIGO) in Hanford, Washington, and Livingston, Louisiana. As well as being another triumph for Einstein's theory of general relativity the discovery of gravitational waves has given astronomers a new tool for observing the universe including rare events like merging blackholes.
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- Of all the far-out concepts in astronomy, blackholes may be the weirdest. A region of space where matter is so tightly packed that nothing, not even light itself, can escape.
As a theoretical possibility, blackholes were predicted in 1916 by Karl Schwarzschild, who found them to be an inevitable consequence of Einstein's theory of general relativity.
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- Roger Penrose and Stephen Hawking later showed that any object collapsing down to a blackhole will form a “singularity” where the traditional laws of physics break down.
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- In the 1930s, Indian astrophysicist Subramanian Chandrasekhar looked at what happens to a star when it has used up all its nuclear fuel. The end result, he found, depends on the star's mass.
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- If that star is really big, say 20 solar masses, then its dense core, which may itself be three or more times the mass of the sun, collapses all the way down to a blackhole. The final core collapse happens incredibly quickly, in a matter of seconds, and it releases a tremendous amount of energy in the form of a “gamma-ray burst“, which is the highest frequency of light..
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- This burst can radiate as much energy into space as an ordinary star emits in its entire lifetime. Telescopes on Earth have detected many of these bursts, some of which come from galaxies billions of light-years away; so we can actually see black holes being born.
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- Blackholes don't always exist in isolation ,sometimes they occur in pairs, orbiting around each other. When they do, the gravitational interaction between them creates ripples in space-time, which propagate outward as gravitational waves.
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- With observatories like the “Laser Interferometer Gravitational-Wave Observatory” and “Virgo“, we now have the ability to detect these waves. The first discovery, involving the merger of two blackholes, was announced back in 2016, and many more have been made since then.
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- As detector sensitivity improves, other wave-generating events besides blackhole mergers are being discovered, such as a crash between a blackhole and a neutron star, which took place way beyond our own galaxy at a distance over 650 million light-years from Earth.
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- The short-lived, high-energy events that produce gamma-ray bursts and gravitational waves may be visible halfway across the observable universe, but for most of their lives blackholes, by their very nature, will be almost undetectable.
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- The fact that they don't emit any light or other radiation means they could be lurking in our cosmic neighborhood without astronomers being aware of it. One way to detect the dark beasts is through their gravitational effects on other stars. When observing the ordinary-looking binary system, or pair of orbiting stars, known as HR 6819 in 2020, astronomers noticed oddities in the motion of the two visible stars that could be explained only if there was a third, totally invisible, object there.
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- When they worked out its mass, at least four times that of the sun, the researchers knew there was only one possibility left. It had to be a blackhole, the closest yet discovered to Earth, a mere thousand light-years away inside our own galaxy.
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- The first observational evidence for a blackhole emerged in 1971, and this too came from a binary star system within our own galaxy. Called Cygnus X-1, the system produces some of the universe's brightest X-rays.
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- These don't emanate from the blackhole itself, or from its visible companion star, which is enormous, at 33 times the mass of our own sun. Rather, matter is constantly being stripped from the giant star and dragged into an accretion disk around the blackhole, and it's from this accretion disk, that the X-rays are emitted
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- . Astronomers can use observed star motion to estimate the mass of the unseen object in Cygnus X-1. The latest calculations put the dark object at 21 solar masses concentrated into such a small space that it couldn't be anything other than a blackhole.
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- Supermassive blackholes, each millions or even billions of solar masses, have been lurking in the centers of galaxies since early in the history of the universe. The central blackholes in these galaxies are surrounded by accretion disks that produce intense radiation at all wavelengths of light.
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- We have evidence that our own galaxy has a blackhole at its center. That's because we see the stars in that region whizzing around so fast, up to 8% of the speed of light, that they must be orbiting something extremely small and massive. Current estimates put the Milky Way's central blackhole around 4,000,000 solar masses.
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- Another piece of evidence for the existence of blackholes is … “spaghettification“. What is spaghettification? When you fall into a blackhole, you get stretched out into thin strands by the blackhole's extreme gravitational pull.
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- In October, 2020, astronomers witnessed this shredding as a flash of light from a star as it was ripped apart. Fortunately, the spaghettifying didn't happen anywhere near Earth, but instead in a galaxy 215,000,000 light-years away.
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- So far we've had plenty of compelling indirect evidence for blackholes: bursts of radiation or gravitational waves, or dynamical effects on other bodies, that couldn't have been produced by any other object known to science.
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- In April ,2019 a direct image of the supermassive blackhole at the center of active galaxy Messier 87 was created. This stunning photo was taken by the Event Horizon Telescope that consists of a large network of telescopes scattered all over the world rather than a single instrument. The more telescopes that can participate, and the more widely spaced they are, the better the final image quality.
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- The result clearly shows the dark shadow of the 6.5 billion-solar-mass blackhole against the orange glow of its surrounding accretion disk. Einstein was right. We have the picture to prove it.
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- November 9, 2021 BLACKHOLES - Einstein’s theories proven right? 3333
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