Joestars & Zeppelis
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Blog#81
Wednesday, April 21st,2021
Welcome back,
We customarily consider time something straightforward and crucial. It streams consistently, free of all the other things, from the past to the future, estimated by clocks and watches. Throughout time, the occasions of the universe succeed each other in a methodical manner: pasts, presents, future. The past is fixed, the future open ... but the entirety of this has ended up being bogus. What we call "time" is a perplexing assortment of constructions, of layers. Under expanding examination, in ever-more prominent profundity, the time has lost layers in a steady progression, piece by piece.
Let’s begin with a simple fact: Time passes faster in the mountains than it does at sea level.
The difference is small, but it can be measured with precision timepieces that you can buy on the internet for a few thousand dollars. With practice, anyone can witness the slowing down of time. With the timepieces of specialized laboratories, researchers can detect this slowing down of time between levels just a few centimeters apart: A clock on the floor runs a little more slowly than one on a table. It is not just the clocks that slow down: Lower down, all processes are slower. Two friends separate, with one of them living in the plains and the other going to live in the mountains. They meet up again years later. The one who has stayed down has lived less, aged less, the mechanism of his cuckoo clock has oscillated fewer times. He has had less time to do things, his plants have grown less, his thoughts have had less time to unfold. Lower down, there is simply less time than at an altitude.
Is this surprising? Perhaps it is. But this is how the world works. Time passes more slowly in some places, more rapidly in others. The surprising thing, perhaps, is that someone understood this slowing down of time a century before we had clocks precise enough to measure it. His name, of course, was Albert Einstein. The ability to understand something before it’s observed is at the heart of scientific thinking. In antiquity, the Greek philosopher Anaximander understood that the sky continues beneath our feet long before ships had circumnavigated the Earth. At the beginning of the modern era, the Polish mathematician and astronomer Copernicus understood the Earth's turns long before astronauts had seen it do so from the moon.
In the course of making such strides, we learn the things that seemed self-evident to us were really no more than prejudices. It seemed obvious the sky was above us and not below; otherwise, the Earth would fall down. It seemed self-evident the Earth did not move; otherwise, it would cause everything to crash. That time passed at the same speed everywhere seemed equally obvious to us. But just as children grow up and discover the world is not as it seemed from within the four walls of their homes, humankind as a whole does the same. What's going on now in a far-off place? Envision, for instance, your sister has gone to Proxima b, the as of late found planet that circles a star around 4 light-years from us. What is your sister doing now on Proxima b?
The lone right answer is that the inquiry has neither rhyme nor reason. It resembles asking, "What is here, in Peking?" when we are in Venice. It has neither rhyme nor reason, since, supposing that I utilize "here" in Venice, I'm alluding to a spot in Venice, not in Peking.
On the off chance that you ask what your sister, who is in the room with you, is doing now, the appropriate response is generally a simple one: You take a gander at her, and you can tell. On the off chance that she's distant, you telephone her and ask what she's doing. Yet, be careful: In the event that you take a gander at your sister, you're accepting light that ventures out from her to your eyes. That light sets aside some effort to contact you — suppose a couple of nanoseconds, a minuscule part of a second. Thusly, you're not exactly seeing what she's doing now yet the thing she was doing a couple of nanoseconds prior.
On the off chance that she's in New York and you telephone her from Liverpool, her voice takes a couple of milliseconds to contact you, so the most you can profess to know is the thing that your sister was up to a couple of milliseconds prior. Not a huge distinction, maybe.
What's the significance here, this "alteration of the design of time"? Definitely, the easing back of time portrayed previously. A mass hinders time around itself. The Earth is a huge mass and hinders time in its area. It does so more in the fields and less in the mountains, on the grounds that the fields are nearer to it. This is the reason the companion who stays adrift level ages all the more gradually.
Subsequently, if things fall, it is because of this easing back of time. Where time passes consistently, in interplanetary space, things don't fall — they drift. Here on the outside of our planet, then again, things fall descending on the grounds that, down there, time is eased back by the Earth.
Thus, despite the fact that we can only with significant effort notice it, the easing back of time by and by has vital impacts: Things fall as a result of it, and it permits us to keep our feet immovably on the ground. In the event that our feet cling to the asphalt, it is on the grounds that our entire body slants normally to where time runs all the more gradually — and time passes more gradually for your feet than it accomplishes for your head.
Does this appear to be unusual? It resembles when watching the sunset, vanishing gradually behind removed mists, we abruptly recollect that it's not the sun that is moving but rather the Earth that is turning. Also, we imagine our whole planet — and ourselves with it — turning in reverse, away from the sun.
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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.
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.
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.
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.
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.
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.
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.
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.
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!
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!
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.
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.
Reblog if you think the girl on the left is just as beautiful as the girl on the right
ive already read some of these, but i wanna check the others too!
I really like reading! I want to recover all mi MBTI’s books I don’t know! :D
Blog# 187
Wednesday, April 27th, 2022
Welcome back,
It’s one of the most compelling questions you could possibly ask, one that humanity has been asking since basically the beginning of time: What’s beyond the known limits? What’s past the edge of our maps? The ultimate version of this question is, What lies outside the boundary of the universe?
The answer is — well, it’s complicated.
To answer the question of what’s outside the universe, we first need to define exactly what we mean by “universe.” If you take it to mean literally all the things that could possibly exist in all of space and time, then there can’t be anything outside the universe. Even if you imagine the universe to have some finite size, and you imagine something outside that volume, then whatever is outside also has to be included in the universe.
Even if the universe is a formless, shapeless, nameless void of absolutely nothing, that’s still a thing and is counted on the list of “all the things” — and, hence, is, by definition, a part of the universe.
If the universe is infinite in size, you don’t really need to worry about this conundrum. The universe, being all there is, is infinitely big and has no edge, so there’s no outside to even talk about.
Oh, sure, there’s an outside to our observable patch of the universe. The cosmos is only so old, and light only travels so fast. So, in the history of the universe, we haven’t received light from every single galaxy. The current width of the observable universe is about 90 billion light-years. And presumably, beyond that boundary, there’s a bunch of other random stars and galaxies.
But past that? It’s hard to tell.
Cosmologists aren’t sure if the universe is infinitely big or just extremely large. To measure the universe, astronomers instead look at its curvature. The geometric curve on large scales of the universe tells us about its overall shape. If the universe is perfectly geometrically flat, then it can be infinite. If it’s curved, like Earth's surface, then it has finite volume.
Current observations and measurements of the curvature of the universe indicate that it is almost perfectly flat. You might think this means the universe is infinite. But it’s not that simple. Even in the case of a flat universe, the cosmos doesn’t have to be infinitely big. Take, for example, the surface of a cylinder.
It is geometrically flat, because parallel lines drawn on the surface remain parallel (that’s one of the definitions of “flatness”), and yet it has a finite size. The same could be true of the universe: It could be completely flat yet closed in on itself.
But even if the universe is finite, it doesn’t necessarily mean there is an edge or an outside. It could be that our three-dimensional universe is embedded in some larger, multidimensional construct. That’s perfectly fine and is indeed a part of some exotic models of physics. But currently, we have no way of testing that, and it doesn’t really affect the day-to-day operations of the cosmos.
And I know this is extremely headache-inducing, but even if the universe has a finite volume, it doesn't have to be embedded.
When you imagine the universe, you might think of a giant ball that’s filled with stars, galaxies and all sorts of interesting astrophysical objects. You may imagine how it looks from the outside, like an astronaut views Earth from a serene orbit above.
But the universe doesn’t need that outside perspective in order to exist. The universe simply is. It is entirely mathematically self-consistent to define a three-dimensional universe without requiring an outside to that universe. When you imagine the universe as a ball floating in the middle of nothing, you’re playing a mental trick on yourself that the mathematics does not require.
Granted, it sounds impossible for there to be a finite universe that has nothing outside it. And not even “nothing” in the sense of an empty void — completely and totally mathematically undefined. In fact, asking “What’s outside the universe?” is like asking “What sound does the color purple make?” It’s a nonsense question, because you’re trying to combine two unrelated concepts.
It could very well be that our universe does indeed have an “outside.” But again, this doesn’t have to be the case. There’s nothing in mathematics that describes the universe that demands an outside.
If all this sounds complicated and confusing, don’t worry. The entire point of developing sophisticated mathematics is to have tools that give us the ability to grapple with concepts beyond what we can imagine. And that’s one of the powers of modern cosmology: It allows us to study the unimaginable.
Bakugo in his winter hero costume icons! ( requested by @routingjoshi )
Thank you for your request!
intp || sapphic. trying to find a place where i can be myself. interests: anime, manga, mythology, horror, universe. every sort of knowledge is welcome(:
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