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#gravity
dear-future-ai · 9 months ago
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One thing physicists never discuss when talking about gravitational waves and higher dimensional space is the giant elephant holding onto a dandelion who can hear our panicked screaming when he shakes us.
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einstinct · a year ago
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i know we talk a lot about crazy literature professors, but i need to tell y’all about my mechanics professor. so, here are some quotes from him just from this morning:
“i know this is all very easy, and it’s 8am, but don’t fall asleep from boredom or i’ll throw my apple in your face.”
“if i walk in a straight line, it’s a 1D movement. if im drunk, and go sideways, it’s 2D. and if i took some crazy shit, i can even be [he starts doing squats while walking/jumping] iN 3D!!!”
“let’s say this apple falls down from the sky. i know, unlikely, but this is physics, it’s supposed to sound magical.”
“oh god, my apple looks terrible. thank god i didn’t eat it before the class or i would’ve been terribly upset.”
[explaining newton’s third law about things tend to attract each other] “you, good lad in the front! i am terribly ATTRACTED to you. but you, other lad in the back - or are you a girl? i don’t know, you have a hat - i am way less attracted to you. don’t be upset guys, we’re talking physics, not physical!”
“of course this book [by his colleague] isn’t perfect, but [raising his voice] I LOVE IT VERY MUCH. [back to whispering] you can never know when your colleagues are spying on you. beware. Eric, if you’re here: so we meet again.”
professor: so what’s g? student: newton?? professor, faking a heart attack: nO. it’s barely 9am and you’re already hurting me, i am LEAVING. (he did leave the class for like two minutes??)
“it’s time for a 7min break. 5 min’s too short, 10′s too long, 7 is average and perfect.” he pauses. “depending on what you’re measuring of course.”
“see, this equation is so easy, i drew a laughing emoji next to it in my notes.” he turns to us and sighs. “yeah. newton and einstein died for this.”
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nasa · a year ago
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Got a question about black holes? Let’s get to the bottom of these odd phenomena. Ask our black hole expert anything! 
Black holes are mystifying yet terrifying cosmic phenomena. Unfortunately, people have a lot of ideas about them that are more science fiction than science. Don’t worry! Our black hole expert, Jeremy Schnittman, will be answering your your questions in an Answer Time session on Wednesday, October 2 from 3pm - 4 pm ET here on NASA’s Tumblr! Make sure to ask your question now by visiting http://nasa.tumblr.com/ask!
Jeremy joined the Astrophysics Science Division at our Goddard Space Flight Center in 2010 following postdoctoral fellowships at the University of Maryland and Johns Hopkins University. His research interests include theoretical and computational modeling of black hole accretion flows, X-ray polarimetry, black hole binaries, gravitational wave sources, gravitational microlensing, dark matter annihilation, planetary dynamics, resonance dynamics and exoplanet atmospheres. He has been described as a "general-purpose astrophysics theorist," which he regards as quite a compliment. 
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Fun Fact: The computer code Jeremy used to make the black hole animations we featured last week is called "Pandurata," after a species of black orchid from Sumatra. The name pays homage to the laser fusion lab at the University of Rochester where Jeremy worked as a high school student and wrote his first computer code, "Buttercup." All the simulation codes at the lab are named after flowers.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
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nemfrog · 3 years ago
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Before you dive. The Body and Health: Grade Six. 1936.
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tvgm · 3 years ago
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When you set gravity to low
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alwaysfckdupinside · 2 years ago
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If I could do it again I wouldn’t change a thing
Cause it’s made me who I am
Against The Current – Gravity
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nasa · a year ago
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May the Four Forces Be With You!
May the force be with you? Much to learn you still have, padawan. In our universe it would be more appropriate to say, “May the four forces be with you.”
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There are four fundamental forces that bind our universe and its building blocks together. Two of them are easy to spot — gravity keeps your feet on the ground while electromagnetism keeps your devices running. The other two are a little harder to see directly in everyday life, but without them, our universe would look a lot different!
Let’s explore these forces in a little more detail.
Gravity: Bringing the universe together
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If you jump up, gravity brings you back down to Earth. It also keeps the solar system together … and our galaxy, and our local group of galaxies and our supercluster of galaxies.
Gravity pulls everything together. Everything, from the bright centers of the universe to the planets farthest from them. In fact, you (yes, you!) even exert a gravitational force on a galaxy far, far away. A tiny gravitational force, but a force nonetheless.
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Credit: NASA and the Advanced Visualization Laboratory at the National Center for Supercomputing and B. O'Shea, M. Norman
Despite its well-known reputation, gravity is actually the weakest of the four forces. Its strength increases with the mass of the two objects involved. And its range is infinite, but the strength drops off as the square of the distance. If you and a friend measured your gravitational tug on each other and then doubled the distance between you, your new gravitational attraction would just be a quarter of what it was. So, you have to be really close together, or really big, or both, to exert a lot of gravity.
Even so, because its range is infinite, gravity is responsible for the formation of the largest structures in our universe! Planetary systems, galaxies and clusters of galaxies all formed because gravity brought them together.
Gravity truly surrounds us and binds us together.
Electromagnetism: Lighting the way
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You know that shock you get on a dry day after shuffling across the carpet? The electricity that powers your television? The light that illuminates your room on a dark night? Those are all the work of electromagnetism. As the name implies, electromagnetism is the force that includes both electricity and magnetism.
Electromagnetism keeps electrons orbiting the nucleus at the center of atoms and allows chemical compounds to form (you know, the stuff that makes up us and everything around us). Electromagnetic waves are also known as light. Once started, an electromagnetic wave will travel at the speed of light until it interacts with something (like your eye) — so it will be there to light up the dark places.
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Like gravity, electromagnetism works at infinite distances. And, also like gravity, the electromagnetic force between two objects falls as the square of their distance. However, unlike gravity, electromagnetism doesn't just attract. Whether it attracts or repels depends on the electric charge of the objects involved. Two negative charges or two positive charges repel each other; one of each, and they attract each other. Plus. Minus. A balance.
This is what happens with common household magnets. If you hold them with the same “poles” together, they resist each other. On the other hand, if you hold a magnet with opposite poles together — snap! — they’ll attract each other.
Electromagnetism might just explain the relationship between a certain scruffy-looking nerf-herder and a princess.
Strong Force: Building the building blocks
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Credit: Lawrence Livermore National Laboratory
The strong force is where things get really small. So small, that you can’t see it at work directly. But don’t let your eyes deceive you. Despite acting only on short distances, the strong force holds together the building blocks of the atoms, which are, in turn, the building blocks of everything we see around us.
Like gravity, the strong force always attracts, but that’s really where their similarities end. As the name implies, the force is strong with the strong force. It is the strongest of the four forces. It brings together protons and neutrons to form the nucleus of atoms — it has to be stronger than electromagnetism to do it, since all those protons are positively charged. But not only that, the strong force holds together the quarks — even tinier particles — to form those very protons and neutrons.
However, the strong force only works on very, very, very small distances. How small? About the scale of a medium-sized atom’s nucleus. For those of you who like the numbers, that’s about 10-15 meters, or 0.000000000000001 meters. That’s about a hundred billion times smaller than the width of a human hair! Whew.
Its tiny scale is why you don’t directly see the strong force in your day-to-day life. Judge a force by its physical size, do you? 
Weak Force: Keeping us in sunshine
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If you thought it was hard to see the strong force, the weak force works on even smaller scales — 1,000 times smaller. But it, too, is extremely important for life as we know it. In fact, the weak force plays a key role in keeping our Sun shining.
But what does the weak force do? Well … that requires getting a little into the weeds of particle physics. Here goes nothing! We mentioned quarks earlier — these are tiny particles that, among other things, make up protons and neutrons. There are six types of quarks, but the two that make up protons and neutrons are called up and down quarks. The weak force changes one quark type into another. This causes neutrons to decay into protons (or the other way around) while releasing electrons and ghostly particles called neutrinos.
So for example, the weak force can turn a down quark in a neutron into an up quark, which will turn that neutron into a proton. If that neutron is in an atom’s nucleus, the electric charge of the nucleus changes. That tiny change turns the atom into a different element! Such reactions are happening all the time in our Sun, giving it the energy to shine.
The weak force might just help to keep you in the (sun)light.
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All four of these forces run strong in the universe. They flow between all things and keep our universe in balance. Without them, we’d be doomed. But these forces will be with you. Always.
You can learn more about gravity from NASA’s Space Place and follow NASAUniverse on Twitter or Facebook to learn about some of the cool cosmic objects we study with light.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
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nemfrog · 8 months ago
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Pegasus re-saddled. 1878. Cover detail. 
Internet Archive
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nasa · 2 years ago
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A Wrinkle in Space-Time: The Eclipse That “Proved” Einstein Right
One hundred years ago a total solar eclipse turned an obscure scientist into a household name. You might have heard of him — his name is Albert Einstein. But how did a solar eclipse propel him to fame?
First, it would be good to know a couple things about general relativity. (Wait, don’t go! We’ll keep this to the basics!)
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A decade before he finished general relativity, Einstein published his special theory of relativity, which demonstrates how space and time are interwoven as a single structure he dubbed “space-time.” General relativity extended the foundation of special relativity to include gravity. Einstein realized that gravitational fields can be understood as bends and curves in space-time that affect the motions of objects including stars, planets — and even light.
For everyday situations the centuries-old description of gravity by Isaac Newton does just fine. However, general relativity must be accounted for when we study places with strong gravity, like black holes or neutron stars, or when we need very precise measurements, like pinpointing a position on Earth to within a few feet. That makes it hard to test!
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A prediction of general relativity is that light passing by an object feels a slight "tug", causing the light's path to bend slightly. The more mass the object has, the more the light will be deflected. This sets up one of the tests that Einstein suggested — measuring how starlight bends around the Sun, the strongest source of gravity in our neighborhood. Starlight that passes near the edge of the Sun on its way to Earth is deflected, altering by a small amount where those stars appear to be. How much? By about the width of a dime if you saw it at a mile and a quarter away! But how can you observe faint stars near the brilliant Sun? During a total solar eclipse!
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That’s where the May 29, 1919, total solar eclipse comes in. Two teams were dispatched to locations in the path of totality — the places on Earth where the Moon will appear to completely cover the face of the Sun during an eclipse. One team went to South America and another to Africa.
On eclipse day, the sky vexed both teams, with rain in Africa and clouds in South America. The teams had only mere minutes of totality during which to take their photographs, or they would lose the opportunity until the next total solar eclipse in 1921! However, the weather cleared at both sites long enough for the teams to take images of the stars during totality.
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The teams took two sets of photographs of the same patch of sky – one set during the eclipse and another set a few months before or after, when the Sun was out of the way. By comparing these two sets of photographs, researchers could see if the apparent star positions changed as predicted by Einstein. This is shown with the effect exaggerated in the image above.
A few months after the eclipse, when the teams sorted out their measurements, the results demonstrated that general relativity correctly predicted the positions of the stars. Newspapers across the globe announced that the controversial theory was proven (even though that’s not quite how science works). It was this success that propelled Einstein into the public eye.
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The solar eclipse wasn’t the first test of general relativity. For more than two centuries, astronomers had known that Mercury’s orbit was a little off. Its perihelion — the point during its orbit when it is closest to the Sun — was changing faster than Newton’s laws predicted. General relativity easily explains it, though, because Mercury is so close to the Sun that its orbit is affected by the Sun’s dent in space-time, causing the discrepancy.  
In fact, we still test general relativity today under different conditions and in different situations to see whether or not it holds up. So far, it has passed every test we’ve thrown at it.
Curious to know where we need general relativity to understand objects in space? Tune into our Tumblr tomorrow to find out!
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You can also read more about how our understanding of the universe has changed during the past 100 years, from Einstein's formulation of gravity through the discovery of dark energy in our Cosmic Times newspaper series.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
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rare-drop · 2 years ago
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Sir Isaac Newton: *Gets bopped on the head with an apple*
Sir Isaac Newton:-
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4gifs · 2 days ago
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Gravity shift
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nasa · a year ago
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Hubble’s 5 Weirdest Black Hole Discoveries
Our Hubble Space Telescope has been exploring the wonders of the universe for nearly 30 years, answering some of our deepest cosmic questions. Some of Hubble’s most exciting observations have been about black holes — places in space where gravity pulls so much that not even light can escape. As if black holes weren’t wild enough already, Hubble has helped us make discoveries that show us they’re even weirder than we thought!
Supermassive Black Holes Are Everywhere
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First, these things are all over the place. If you look at any random galaxy in the universe, chances are it has a giant black hole lurking in its heart. And when we say giant, we’re talking as massive as millions or even billions of stars! 
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Hubble found that the mass of these black holes, hidden away in galactic cores, is linked to the mass of the host galaxy — the bigger the galaxy, the bigger the black hole. Scientists think this may mean that the black holes grew along with their galaxies, eating up some of the stuff nearby.
Some Star Clusters Have Black Holes
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A globular cluster is a ball of old, very similar stars that are bound together by gravity. They’re fairly common — our galaxy has at least 150 of them — but Hubble has found some black sheep in the herd. Some of these clusters are way more massive than usual, have a wide variety of stars and may even harbor a black hole at the center. This suggests that at least some of the globular clusters in our galaxy may have once been dwarf galaxies that we absorbed.
Black Hole Jets Regulate Star Birth
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While black holes themselves are invisible, sometimes they shoot out huge jets of energy as gas and dust fall into them. Since stars form from gas and dust, the jets affect star birth within the galaxy. 
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Sometimes they get rid of the fuel needed to keep making new stars, but Hubble saw that it can also keep star formation going at a slow and steady rate.
Black Holes Growing in Colliding Galaxies
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If you’ve ever spent some time stargazing, you know that staring up into a seemingly peaceful sea of stars can be very calming. But the truth is, it’s a hectic place out there in the cosmos! Entire galaxies — these colossal collections of gas, dust, and billions of stars with their planets — can merge together to form one supergalaxy. You might remember that most galaxies have a supermassive black hole at the center, so what happens to them when galaxies collide? 
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In 2018, Hubble unveiled the best view yet of close pairs of giant black holes in the act of merging together to form mega black holes!
Gravitational Wave Kicks Monster Black Hole Out of Galactic Core
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What better way to spice up black holes than by throwing gravitational waves into the mix! Gravitational waves are ripples in space-time that can be created when two massive objects orbit each other. 
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In 2017, Hubble found a rogue black hole that is flying away from the center of its galaxy at over 1,300 miles per second (about 90 times faster than our Sun is traveling through the Milky Way). What booted the black hole out of the galaxy’s core? Gravitational waves! Scientists think that this is a case where two galaxies are in the late stages of merging together, which means their central black holes are probably merging too in a super chaotic process. 
Want to learn about more of the highlights of Hubble’s exploration? Check out this page! https://www.nasa.gov/content/goddard/2017/highlights-of-hubble-s-exploration-of-the-universe
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
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tumbling-darkling · 2 months ago
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Dannymay Day 8 - Gravity
So let’s say one night closely following the accident, Danny wakes up with his nose touching the ceiling and freaks out, afraid his parents would find him looking like a kid from the Exorcist. So he buys some weighted blankets (or the equivalent because those things are expensive so he just stuffs heavy stuff into a blanket) and trains himself to NOT float when he sleeps. The thing is, a body and mind doesn’t always work together, and what he accidently did train his body, but to stay in whatever position he fell asleep in. So good thing, he doesn’t float UP. But gravity is non existent to him when he sleeps so now he just remains in place.
Kwan and Dash suddenly think that Danny has really extreme upper body strength and Dash leaves him alone for the following month in fear of pushing Danny so far, he would snap and throw a very intense punch that Dash full heartedly believes will shatter his ribs.
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nasa · 3 months ago
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Black Holes: Seeing the Invisible!
Black holes are some of the most bizarre and fascinating objects in the cosmos. Astronomers want to study lots of them, but there’s one big problem – black holes are invisible! Since they don’t emit any light, it’s pretty tough to find them lurking in the inky void of space. Fortunately there are a few different ways we can “see” black holes indirectly by watching how they affect their surroundings.
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Speedy stars
If you’ve spent some time stargazing, you know what a calm, peaceful place our universe can be. But did you know that a monster is hiding right in the heart of our Milky Way galaxy? Astronomers noticed stars zipping superfast around something we can’t see at the center of the galaxy, about 10 million miles per hour! The stars must be circling a supermassive black hole. No other object would have strong enough gravity to keep them from flying off into space.
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Two astrophysicists won half of the Nobel Prize in Physics last year for revealing this dark secret. The black hole is truly monstrous, weighing about four million times as much as our Sun! And it seems our home galaxy is no exception – our Hubble Space Telescope has revealed that the hubs of most galaxies contain supermassive black holes.
Shadowy silhouettes
Technology has advanced enough that we’ve been able to spot one of these supermassive black holes in a nearby galaxy. In 2019, astronomers took the first-ever picture of a black hole in a galaxy called M87, which is about 55 million light-years away. They used an international network of radio telescopes called the Event Horizon Telescope.
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In the image, we can see some light from hot gas surrounding a dark shape. While we still can’t see the black hole itself, we can see the “shadow” it casts on the bright backdrop.
Shattered stars
Black holes can come in a smaller variety, too. When a massive star runs out of the fuel it uses to shine, it collapses in on itself. These lightweight or “stellar-mass” black holes are only about 5-20 times as massive as the Sun. They’re scattered throughout the galaxy in the same places where we find stars, since that’s how they began their lives. Some of them started out with a companion star, and so far that’s been our best clue to find them.
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Some black holes steal material from their companion star. As the material falls onto the black hole, it gets superhot and lights up in X-rays. The first confirmed black hole astronomers discovered, called Cygnus X-1, was found this way.
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If a star comes too close to a supermassive black hole, the effect is even more dramatic! Instead of just siphoning material from the star like a smaller black hole would do, a supermassive black hole will completely tear the star apart into a stream of gas. This is called a tidal disruption event.
Making waves
But what if two companion stars both turn into black holes? They may eventually collide with each other to form a larger black hole, sending ripples through space-time – the fabric of the cosmos!
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These ripples, called gravitational waves, travel across space at the speed of light. The waves that reach us are extremely weak because space-time is really stiff.
Three scientists received the 2017 Nobel Prize in Physics for using LIGO to observe gravitational waves that were sent out from colliding stellar-mass black holes. Though gravitational waves are hard to detect, they offer a way to find black holes without having to see any light.
We’re teaming up with the European Space Agency for a mission called LISA, which stands for Laser Interferometer Space Antenna. When it launches in the 2030s, it will detect gravitational waves from merging supermassive black holes – a likely sign of colliding galaxies!
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Rogue black holes
So we have a few ways to find black holes by seeing stuff that’s close to them. But astronomers think there could be 100 million black holes roaming the galaxy solo. Fortunately, our Nancy Grace Roman Space Telescope will provide a way to “see” these isolated black holes, too.
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Roman will find solitary black holes when they pass in front of more distant stars from our vantage point. The black hole’s gravity will warp the starlight in ways that reveal its presence. In some cases we can figure out a black hole’s mass and distance this way, and even estimate how fast it’s moving through the galaxy.
For more about black holes, check out these Tumblr posts!
⚫ Gobble Up These Black (Hole) Friday Deals!
⚫ Hubble’s 5 Weirdest Black Hole Discoveries
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
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krisinsanity · 2 years ago
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D.O  | DON’T MESS UP MY TEMPO  (2018) / CIRCUIT / GRAVITY
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faronmckenzie · 3 years ago
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Time is relative, and flexible and, according to Einstein, “the dividing line between past, present, and future is an illusion”. So reality is ultimately TIMELESS. This sounds pretty bizarre from the view of classical physics, but from the view of consciousness theory and spirituality, it fits in perfectly.
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