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slYnki: 2006-04-24 05:31:48 am
XXY
Quote:
He asked about "contrast". What's the brightness of a black hole? 0. What's the brightness of a supernova? Brighter than any other object in the universe. The fact that a supernova might leave behind a black hole has nothing to do with it.  Tongue

* Of course, black holes are still unproven to even exist, blah blah blah.


Black holes exist. Can't remember if there's one in The Milky Way or not... Supernovas are quite rare in our galaxy. In fact, only one goes off about every hundred years. There are two types of supernovas. One type involves a white dwarf (one of the dimmest, but hottest type of stars in the universe) in a binary system with a larger star. The white dwarf pulls in matter from its companion star. When the white dwarf can no longer sustain itself, it collapses, setting off a cataclysmic, thermonuclear explosion, or supernova.

Most supernovas, however, are massive stars that have consumed all their own available fuel. In this kind of core-collapse supernova, the star's core shrinks. It gets denser and hotter - hot enough to fuse oxygen and carbon into heavier elements. Eventually, the core is solid iron, and its enormous mass causes it to collapse - in about one second. So much energy is released that the star blasts into space. In the aftermath, the core becomes a neutron star or a black hole, depending on its mass.

Anyways, I was confused when you said supernovas are the brightest object in the universe. For one, they're not objects, and second, I got that confused with Flares, the biggest explosions in the universe. Thought they were the brightest in the universe. I'm sure there's something brighter in our universe than a supernova, just can't think of what at the moment. It's probably just a supernova, and I'm thinking for no reason. Also, as a fun addition, the brightest supernova seen from Earth in 400 years - the star actually exploded 160,000 years ago, the time it has taken for its light to reach us.

Now, to own black holes: Black holes are collapsed pieces of our universe where time and space as we know it cease to exist. All that identifies a black hole is a remnant gravitational field that is so intense that nothing can escape once it is sucked in, even light. Today, black holes are more than a theoretical curiousity. Astronomers have discovered them hidden in the cores of galaxies, and much closer to home in our galactic suburbs.

As I've said before, black holes form when a massive star runs out of fueld and explodes in a supernova. If the surviving stellar core is three times more massive than our Sun, nothing can stop it from imploding. The result is a singularity, a scrunched piece of the universe with almost no volume and infinite density. Surrounding the singularity is a boundary called the event horizon. The more massive the black hole, the bigger the event horizon. But the singularity always remains smaller than the period at the end of this sentence. Anything that crosses the event horizon is trapped forever because the needed escape velocity is faster than the velocity of light - the universe's speed limit.

One day I was walking in the field with my girlfriend looking at the stars and I said, "holy shit, I should learn about those things."


Quote:
They both satisfy your hunger, but chocolate is just that much sweeter.  


Something's wrong with your ice cream, then. Chocolate isn't sweet.

Just regular chocolate isn't sweet at all. It looks amazingly tasty, but it's the most bitter thing in the world. My mom fooled me with it once, and I nearly gagged to death. It's alarming how sweet chocolate bars are.... But anyways, I don't think VG was saying his chocolate was sweet in a literal sense, I think he was just saying chocolate ruled, which it does on occasion.


EDIT: I was thinking about that brightest thing, and I figured I'd mention what's going to happen when our sun explodes in the next billion years or whenever.... While our sun is actually quite dim and pathetic next to other star, its exit will be an impressive one. Eventually, the sun will burn out it's source of hydrogen, and will begin to burn only helium. It will balloon to 300x its size, consuming Mercury and Venus. Then, it'll explode. Light from the sun takes 8 minutes to reach earth, so in 8 minutes, Earth will be shrouded in darkness.
dinosaur from the past
Damn puns.
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Off-topic marathon...

Actually, Radix is correct; they [black holes] are still theoretical and cannot be empirically proven. (Although I understand what you mean, Pocari; nobody denies that they exist.)  In the same fashion, we haven't proven that electrons exist, either. Of course, they are nearly perfect theoretical entities, the two of them... 

[/unprogressive post for April]
Invisible avatar
Quote:
Actually, Radix is correct; they [black holes] are still theoretical and cannot be empirically proven. (Although I understand what you mean, Pocari; nobody denies that they exist.)  In the same fashion, we haven't proven that electrons exist, either. Of course, they are nearly perfect theoretical entities, the two of them...


Actually, they can be detected Tongue It's very hard, especially when black hole stands alone in space. Gravitational lensing helps us detect them. But most of black holes are surrounded by matter, which collapses upon them. This matter creates an accretion disc, and while getting closer and closer to hole, it gains kinetic energy and loses mass, which, when particles collide, is transfered mostly to energy, making surrounding of black hole hotter and hotter, and emits electromagnetic waves of the whole spectrum, from X-ray and gamma to television and radio waves. It also emits high energy particles. That makes black holes surrounded by matter actually the most bright objects in the universe! It's strange, i know Grin
There is a black hole in Milky Way...actually, it's in center of it, in it's core Tongue
In 2004, two big black holes were detected in our universe, one in galaxy in constellation Ursa Major, and second one is in our galaxy, in a claster of seven stars, which helps theory that super-massive black holes "eat" surrounding matter, getting bigger and bigger.

Oh, and PoCari, process of Sun blowing itself up after losing all of its "fuel" will take aproximately 5 billion years. Also, along with light, we would lose gravity from Sun after those 8 minutes and 19 seconds needed for them to get to Earth from Sun. Earth would start to go in a straight line instead of elipse in one second, and inertia of Earth would give us catastrophic consequences...
But not like we're going to see this anyway Tongue
Fucking Weeaboo
Quote:
Something's wrong with your ice cream, then. Chocolate isn't sweet. Maybe it's that Like Like that's gotten into your chocolate ice cream... does anyone know if Like Likes are sweet? TSA?

~_^


Weren't we talking about slang and such?  Like SWEET DUDETTE!

And honestly, sweet chocolate sucks.  Give me some nice dark chocolate.

Speaking of ice cream, how long have I had that pint of hagen daus in my freezer? >_>;;

*stratches head*
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Dex: Now wait; there's a dramatic difference between indirect evidence and affirmative proof.  Black holes, no matter how much scientific data might support them, will always be theoretical entities.  We can only indirectly observe them; that is, we can only detect how they affect their surroundings, including light, and so forth, as you mentioned in detail.  It is apodeicticallly impossible, though, that we could ever have direct, sensory experience of them.  In this manner, they are destined, forever, to be only theoretical. 

That being said, they are so logically coherent that it's irrational to deny their existence.  Again, we cannot prove the existence of electrons, but all of our empirical data not only suggests them, but might prove their existence via ad absurdum in the denial.  They make so much sense, in other words, that our scientific structure becomes complete with their inclusion, and becomes self-contradicting without them.

EDIT:  Well said, my friend.  Wink
Edit history:
dex: 2006-04-24 09:12:56 pm
Invisible avatar
I agree completely - you can't touch, watch or listen to black holes. There will never be enough evidence to fully confirm their existence. But by using these indirect means of observing black holes, we can confirm that objects exactly like them or very alike to them are around. Basing on both of Einstein's relativity theories, only objects like black holes can make such anomalies. Of course, this theory can have some errors in it, and it's possible that some new quantium theory will make black holes not needed in such processes. But then again, relativity theories never proved to be wrong about gravity and time distruption around matter.
But, as you well put it, we won't be able to touch black holes, just as we can't do so with electrons, tachions, time before the Big Bang and so on.
Because of that theoretical nature, there are many theories that tell about mass, charge and momentum of black holes, like Schwarzschild theory, telling only mass is not equal to zero in black hole, or Reissner – Nordströms theory, which tells charge and mass are not zero, and there is no momentum.
Edit history:
slYnki: 2006-04-25 12:12:48 am
XXY
Quote:
But, as you well put it, we won't be able to touch black holes, just as we can't do so with electrons, tachions, time before the Big Bang and so on.

You don't have to touch something to know that it exists. I can't seem to touch oxygen, but I can breathe pretty decently =)

I didn't know that electrons haven't been proven to exist. That doesn't make any sense.... I've heard so much things about electrons throughout my years of science, omfg... A bunch of experiments that proved the existance of them, charges of elements, ect. ect. Well, you learn something new everyday, I guess.

But in any event, black holes are merely a theoretical curiousity. We know that they're out there, but it's simply a curiousity. God damnit, now I'm all confused. Stupid scientists, they do this to us on purpose. It's a conspiracy, I'm positive.


EDIT: Ooh, and dex, I didn't know that gravity would flop too. Although, that's painfully obvious when I actually give it a second or two of thought. That's really awesome. It won't be for the people in 5 million years of course, but by then, we'll be extinct anyways. Fuck, I don't want to think about death...

<3 intelligent conversations.
I'm addicted to games
sheesh wtf did i start.
btw, the sun won't explode... just expand for a few million years into a red giant and then shrink into a white drawf.