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3846 - GRAVITYWAVES
- so weak and powerful. Gavity isn't just a force that keeps things
holds us to the ground. General
Relativity tells us that gravity makes gravitational waves, or ripples in the
fabric of space-time. But, how do these gravitational waves work,
exactly?
--------- 3846 - GRAVITYWAVES - so weak and powerful.
- Shortly after formulating his general
theory of relativity, Albert Einstein realized that gravity can make waves.
However, he quickly doubted his own conclusions. The realization that
gravitational waves exist came from a simplified form of general relativity,
and Einstein didn't know if the waves were real or just an artifact of the
simplification process.
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- The equations of general relativity are
notoriously difficult to solve, so it's no surprise that even Einstein
equivocated about this. It took several decades before physicists came to the
firm conclusion that general relativity does support gravitational waves. In
other words, they are indeed a real thing.
Pretty much
anything in the universe doing anything at all makes gravitational waves. All
it takes is a little wiggling, which gravitational waves have in common with
pretty much any other wave. If you wiggle around in water, you make water
waves.
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- If your voice box wiggles around, it makes
sound waves. If you wiggle an electron, you make electromagnetic waves. To make
a gravitational wave, all you need to do is make mass accelerate.
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- These waves travel outward from the source
at the speed of light and are ripples in the force of gravity. When a
gravitational wave passes through you, you get stretched and squeezed as if
giant hands were playing with you like a piece of putty.
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- Even though pretty much everything in the
universe is making gravitational waves all the time, you don't really notice
them. Gravity is, by far, the weakest of the four fundamental forces of nature.
Even if gravity were a billion billion billion times stronger than it is, it
would still be orders of magnitude weaker than any of the other forces: the
weak force, electromagnetism and the strong force.
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- Gravitational waves are weaker still; they
are tiny perturbations on top of the normal gravity.
-
- To make a serious dent in space-time, you
need some serious mass and energy action, stuff like black hole collisions,
neutron star smashups, supernovas, giant black holes that consume stars whole
or even the chaotic forces unleashed in the earliest moments of the Big Bang.
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- If you were within about half a mile of two
black holes merging, the gravitational waves emitted would be strong enough to
tear you apart. But if you were hundreds of miles away, it wouldn't even make
the hair on the back of your neck stand on end.
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- From our vantage point on Earth, millions
or billions of light-years away from these cataclysmic events, the
gravitational waves have an amplitude no bigger than the width of a proton.
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- The extreme weakness of gravitational waves
is why it took nearly a quarter century of technological development to detect
them. But in 2015, the Laser Interferometer Gravitational-Wave Observatory
(LIGO) confirmed the first direct detection of gravitational waves. The source
of that particular signal was two black holes merging 1.4 billion light-years
away.
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- Because gravity is so weak, the
gravitational waves barely interact with matter, thereby allowing them to
propagate freely throughout the universe without scattering or being absorbed.
It also means we can see things we normally couldn't.
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- If two black holes collide in the middle of
space, how could we really see them? If they don't emit any form of
electromagnetic radiation during the collision, the entire process is invisible
to our telescopes. But those collisions release tremendous amounts of energy in
the form of gravitational waves, usually more power than that produced by all
of the stars in the universe combined.
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- Since that first confirmed detection in
2015, LIGO and Virgo, its sibling observatory in Italy, have confirmed over
four dozen black hole collisions. We've gone from the occasional gravitational
wave detection to a full-fledged branch of astronomy.
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- These subtle vibrations have unlocked
insight into the inner workings of the cosmos and newfound mysteries for the
next generation of astronomers. The
gravity of it all. Amazing!
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January 26, 2022 GRAVITYWAVES
- so weak and powerful. 3846
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--------------------- --- Friday, January 27, 2023 ---------------------------
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