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Theory of relativity by Supersonicdarky on 11-15-2005 at 08:21 PM

i did quite a bit of googleing, but i can't find it in simple english, it always has words i don't understand or it just doesn't make sense

could someone xplain it to me so i could understand?


RE: Theory of relativity by prashker on 11-15-2005 at 08:25 PM

Theory of motion and energy developed by Albert Einstein in the 20th century.

edit: also look here http://en.wikipedia.org/wiki/Theory_of_relativity


RE: Theory of relativity by kierant on 11-15-2005 at 08:28 PM

lol, I think he wanted an actual explanation. Nice try though. (edit: oh you edited your post :p)


PS. I'm having a search at the moment to see if i can find anything reasonably understandable.


RE: Theory of relativity by Ezra on 11-15-2005 at 08:31 PM

I believe it is:

When you go as fast as light you transform into light yourself

and

The faster you go the slower time goes



But I'm not sure :P


RE: RE: Theory of relativity by Supersonicdarky on 11-15-2005 at 08:34 PM

quote:
Originally posted by Ezra
When you go as fast as light you transform into light yourself

Never heard that

quote:
Originally posted by Ezra
The faster you go the slower time goes

i know that :)
RE: Theory of relativity by user27089 on 11-15-2005 at 08:35 PM

Basically what Ezra said...

If you stand still, then time goes faster... Whereas, when you're travelling, the faster you're going, the slower time is going itself...


RE: Theory of relativity by Plik on 11-15-2005 at 08:36 PM

quote:
Originally posted by Ezra
When you go as fast as light you transform into light yourself

and

The faster you go the slower time goes

I think its:
It is impossible to go beond the speed of light because it would require an infinate amount of energy (or somthing like that).
and, speed is relative, for example a car is going 100mph down a road. The car is going 100mph in relitivity to the road, but the driver is going 0mph in relitivity to the car.
and it also covers "The faster you go the slower time goes".

But like Ezra im not sure :P
RE: Theory of relativity by Ezra on 11-15-2005 at 08:39 PM

So that basicly means that interstellar spacetravel is not practical :P

Cause when you want to go to another galaxy you need to go VERY fast say 0.99 the speed of light (not 1 times cause then you transform into light ;-)), But that causes the time to slow down for you, and thus from you perspective speed up time on earth, meaning when you come back, you aged not so much, but earth is centuries further :P

EDIT: also another thing I thougt about...

Speed is relative to the time it takes you to cover an amount of distance.

But because when you go very fast, time slows down, means it takes you the same time to cover a certain distance.

But again, that's something I thought would be the case, and not even sure if it's true :P
Let's call that "Ezra's theory of relativity :P"


RE: Theory of relativity by ShawnZ on 11-15-2005 at 08:42 PM

You don't transform into light if you go the speed of light. (You'll turn yourself into a black hole though)


RE: Theory of relativity by SikStyles on 11-15-2005 at 08:50 PM

wasnt the theory of relativity that when you sit in a room with a hot chick an hour seems like a second and when you sit on a hot stove a second seems like an hour

im not sure though.


RE: Theory of relativity by Negro_Joe on 11-15-2005 at 08:50 PM

i think its a about speed mainly,

for example, your on a train, you see the scenery woosh past, you think your going fast, but related to the spinning of the globe your not..:P

this is me trying to sound clever, i read this somwhere i think its wrong but you get the idea...


RE: Theory of relativity by Ezra on 11-15-2005 at 08:54 PM

After reading some,

I believe the theory is, that when say you travel with in a car that's going 50 mph, another car passes also going 50 mph, it seems that the car is going 100mph. BUT when going almost the speed of light this is not the case...

Say you travel in your spaceship with 0.99 the speed of light and another spaceship passes also going 0.99, it still looks like it's going 0.99

Then what was what I said before? :S


RE: Theory of relativity by emit on 11-15-2005 at 08:58 PM

There are two theories of relativity: special and general. I doubt you want the general one explained because it is vastly complicated and reserved for PhD level research only. There are two parts to the special theory of relativity:
1. That, in a vacuum, the speed of light is constant no matter your frame of reference, the inertia of the observers or the velocity of the object emitting the light. (c)
2. Basically that the laws of physics do not depend on the state of inertial motion.

The theory is basically E = mc². That's the widely known usage, to be physically correct it is: (delta)E = c²(delta)m. The change in energy is equal to the speed of light squared multiplied by the change in mass.

That's the fundamental, underlying stuff about it. That was basically me reciting what I remembered from my uni textbook. Heh.

Of course the effects of this theory are more widely known, i.e. the faster you travel the slower time goes, so if you travel really fast you age slower.

A small expansion to tantalise everyone:
Theoretically, purely as a mathematical construct, one thing can travel faster than the speed of light.
Imagine you have a donkey equidistant from two bales of hay that are exactly the same, EXACTLY the same... which bale does the donkey choose?
That's the analogy, and it forms a perfect symmetry. When that symmetry is broken (where such a symmetry exists) a particle called a tachyon is created and emitted, which travels faster than light.


RE: Theory of relativity by Supersonicdarky on 11-15-2005 at 08:58 PM

technicly you wouldn't see the other spaceship, it passes by too fast :P

but y is it the 50+50=100 and 0.99+0.99=0.99? :S


RE: Theory of relativity by Ezra on 11-15-2005 at 09:02 PM

quote:
Originally posted by Supersonicdarky
but y is it the 50+50=100 and 0.99+0.99=0.99?

That's not completely true.
I said 50 mph and .99 speed of light.

And what Time said can be read at wikipedia, but we wanted it explained for the people that don't understand that :P

And other thing: Some scientist managed to slow down light to 17 meters per second, and also stop it momentarily


RE: RE: Theory of relativity by Supersonicdarky on 11-15-2005 at 09:03 PM

quote:
Originally posted by Ezra
And other thing: Some scientist managed to slow down light to 17 meters per second, and also stop it momentarily

link to source?
RE: Theory of relativity by MoRiA on 11-15-2005 at 09:04 PM

quote:
Originally posted by Ezra
And other thing: Some scientist managed to slow down light to 17 meters per second, and also stop it momentaraly
Which is why we say that c is the speed of light in a vacuum. It's ever so slightly slower in normal air than it is in a vacuum (but so inperceptibly so that we can just use c in most of our calculations...).
RE: Theory of relativity by emit on 11-15-2005 at 09:06 PM

quote:
Originally posted by Ezra
And what Time said can be read at wikipedia, but we wanted it explained for the people that don't understand that :P

And other thing: Some scientist managed to slow down light to 17 meters per second, and also stop it momentarily

Yes, it can be. Though I remember it all from Contemporary Physics classes. That was written from memory, hence all my edits. :(
Light travels at different speeds in different media, i.e. it travels slower in water, slower in glass... c is only its speed in a vacuum.

RE: Theory of relativity by Ezra on 11-15-2005 at 09:07 PM

quote:
Originally posted by MoRiA
Which is why we say that c is the speed of light in a vacuum. It's ever so slightly slower in normal air than it is in a vacuum (but so inperceptibly so that we can just use c in most of our calculations...).
Yeah I know that :), I just thought It was pretty clever :P (That's also why light slows down 30% in a fiber optic cable)

About that thing with the spaceships:
quote:
Originally posted by wikipedia
if two cars approach each other from opposite directions, each travelling at a speed of 50 kilometres per hour (31 miles per hour), one expects that each car will perceive the other as approaching at a combined speed of 50 + 50 = 100 km/h (62 mph) to a very high degree of accuracy.

At velocities at or approaching the speed of light, however, it becomes clear from experimental results that this rule does not apply. Two spaceships approaching each other, each travelling at 90% the speed of light relative to some third observer between them, do not perceive each other as approaching at 90% + 90% = 180% the speed of light; instead they each perceive the other as approaching at slightly less than 99.5% the speed of light.

Source: http://en.wikipedia.org/wiki/Speed_of_light
RE: Theory of relativity by ShawnZ on 11-15-2005 at 09:14 PM

Not that we would see the spaceship, because our eyes don't even capture images that fast.


RE: Theory of relativity by Ezra on 11-15-2005 at 09:16 PM

quote:
Originally posted by ShawnZ
Not that we would see the spaceship, because our eyes don't even capture images that fast.
That's why they call it a THEORY :P
RE: Theory of relativity by Yousef on 11-15-2005 at 09:39 PM

http://en.wikipedia.org/wiki/Special_relativity_for_beginners

That one might help, though it still isn't very easy.

I saw a nice documentary about Einstein a week ago. Everything was explained quite clear, except the most important thing: 'Spacetime'. There was a nice animation though showing mercurius & the sun and some kind of spacetime-grid...

Edit: it looked someting like this:

[Image: spacetime-deviation.jpg]


RE: Theory of relativity by qgroessl on 11-15-2005 at 09:52 PM

Our science teacher had a thing on tape from a TV program basically about Einstein's E=mc2...  It branched off into many other scientists that aided in all the basics of the equation. A few of the ways they portrayed it on the video were.

Einstein and his wife were sitting on a bench next to a river. Watching a small boat with a woman on it go by. From where Einstein was sitting, it looked as if the waves were traveling faster than the boat and that there was more than one.    From the lady riding the boats perspective, it was a single wave, that was motionless because it traveled the speed of the boat.

What they got outta that was basically, if they were to be in a car traveling the speed of light, they would see the waves of light moving alongside the car, which they proved untrue because no matter how fast your going, light is still going an equal speed away... Therefore you seem to be catching up to light, but you're just slowing down time.

From my understanding the only thing that can go faster than the speed of light, is light itself. Which makes little sense to me still... But I'm very interested in this... It's the only interesting thing in science as far as I'm concerened.

It got me to thinking if a black hole in space, is just a place where the light cannot escape the gravitational forces... if we were to make something (ourselves or something else) go faster than light itself, we'd disappear?


To tell you the truth *again*... I don't like science much at all.... except for things that we can't completely explain... such as this.



EDIT: Although now I know I'm not even near completely correct... I found  website on the television program my teacher showed us. Take a look at it here!


RE: Theory of relativity by Supersonicdarky on 11-15-2005 at 10:01 PM

i was watching "how william shatner changed the world" on sunday, thats where i got the eholr idea about this. It said that you might be able to travel fasteer than light. It was something like removing space infront of you, and putting it behind you, didn't really make much sense tho... :undecided:

and like qgrossel, this is one of the few things in science i'm intersted in :)


RE: Theory of relativity by Ezra on 11-15-2005 at 10:10 PM

quote:
Originally posted by Supersonicdarky
It said that you might be able to travel faster than light. It was something like removing space infront of you, and putting it behind you, didn't really make much sense tho...

Yeah I heard about that too, it involves bending the space around you or something.

RE: Theory of relativity by qgroessl on 11-15-2005 at 10:12 PM

This is one of the articles of the website I showed at the end of my previous post. This explains my boat theory much better ;).... haha... It's like the same thing.... Except I think I might've been backwards?

quote:
Imagine a police officer chasing after a speeding motorist. If he drives fast enough, the officer knows that he can catch the motorist. Anyone who has ever gotten a ticket for speeding knows that. But if we now replace the speeding motorist with a light beam, and an observer witnesses the whole thing, then the observer concludes that the officer is speeding just behind the light beam, traveling almost as fast as light. We are confident that the officer knows he is traveling neck and neck with the light beam.

But later, when we interview him, we hear a strange tale. He claims that instead of riding alongside the light beam as we just witnessed, it sped away from him, leaving him in the dust. He says that no matter how much he gunned his engines, the light beam sped away at precisely the same velocity. In fact, he swears that he could not even make a dent in catching up to the light beam. No matter how fast he traveled, the light beam traveled away from him at the speed of light, as if he were stationary instead of speeding in a police car.

But when you insist that you saw the police officer speeding neck and neck with the light beam, within a hairsbreadth of catching up to it, he says you are crazy; he never even got close. To Einstein, this was the central, nagging mystery: How was it possible for two people to see the same event in such totally different ways? If the speed of light was really a constant of nature, then how could a witness claim that the officer was neck and neck with the light beam, yet the officer swears that he never even got close?

Einstein had realized earlier that the Newtonian picture (where velocities can be added and subtracted) and the Maxwellian picture (where the speed of light was constant) were in total contradiction. Newtonian theory was a self-contained system, resting on a few assumptions. If only one of these assumptions were changed, it would unravel the entire theory in the same way that a loose thread can unravel a sweater. That thread would be Einstein's daydream of racing a light beam.

EDIT:... Now I found why reaching the speed of light is impossible. It's a bit confusing... But useful none the less.

quote:
Einstein then pushed further and made the next fateful leap. He wrote a small paper, almost a footnote, late in 1905 that would change world history. If meter sticks and clocks became distorted the faster you moved, then everything you can measure with meter sticks and clocks must also change, including matter and energy. In fact, matter and energy could change into each other. For example, Einstein could show that the mass of an object increased the faster it moved. (Its mass would in fact become infinite if you hit the speed of light—which is impossible, which proves the unattainability of the speed of light.) This meant that the energy of motion was somehow being transformed into increasing the mass of the object. Thus, matter and energy are interchangeable.

RE: Theory of relativity by Underlord on 11-16-2005 at 12:41 AM

quote:
Originally posted by qgroessl
From my understanding the only thing that can go faster than the speed of light, is light itself. Which makes little sense to me still... But I'm very interested in this... It's the only interesting thing in science as far as I'm concerened.
The only thing that can travel faster than light is space. In a black hole space is being sucked in faster than light travels, so light itself cannot escape. Very simple explination.

Einstein also concluded that gravity was not a force but a warping of space and time. Light itself is susceptible to gravity.

Also as velocity increases so does mass. If velocity is at the speed of light (c) then mass is infinate.

As velocity increases time relative to the person experiencing the velocity slows down. If velocity is at the speed of light (c) then time relative to the observer stops.

Thus to reach the speed of light is impossible. Mass would be infinate and time would stop.
RE: RE: Theory of relativity by Supersonicdarky on 11-16-2005 at 12:58 AM

quote:
Originally posted by Underlord
quote:
Originally posted by qgroessl
From my understanding the only thing that can go faster than the speed of light, is light itself. Which makes little sense to me still... But I'm very interested in this... It's the only interesting thing in science as far as I'm concerened.
The only thing that can travel faster than light is space. In a black hole space is being sucked in faster than light travels, so light itself cannot escape. Very simple explination.

Einstein also concluded that gravity was not a force but a warping of space and time. Light itself is susceptible to gravity.

Also as velocity increases so does mass. If velocity is at the speed of light (c) then mass is infinate.

As velocity increases time relative to the person experiencing the velocity slows down. If velocity is at the speed of light (c) then time relative to the observer stops.

Thus to reach the speed of light is impossible. Mass would be infinate and time would stop.


not really, it's not faster than the speed of light, it has a huge gravity, thats why light can't escape


i also wonder if there is something non-physical that can travel faster than light... :S
RE: Theory of relativity by superjugy on 11-16-2005 at 01:19 AM

Im in high school, and i live in mexico, here the science isnt very advance and in high school we dont learn this things, but i investigate myself, as far as i know E=mc2 means that any mass going to the square of the speed of light then it would transform into enrgy. about the black hole thingy, well if you go to speed of lght, nothing will actually happens to you, because the light itself travels at speed of light and nothing happens to it. now i think that einstein didnt knew the actual speed of light and he was just supposing that the speed of light is the quickest thing in the world. maybe as far as we know is the quickest thing but what about all the types of light that exist beside the visible light? also why would exactly the speed of light would make something to change, the speed is just the mesurement to know how much distance you travel in certain time. and as far as i know the black holes are formed when suns explode and die. nothing to do with speed of light. and for the spacetime, as far as i know it is like another dimension intead of having time and distance separeeted they are in just 1 dimension. and thats why einstein said that gravity isnt actually a force like newton said, it is a curve spacetime that the planet creates and also the sun and that makes the gravity. i saw that picture with spacetime grid too. but all of this is just an opinion of a 17 year old guy in mexico, i might be, very very wrong or very very right. ;)


RE: Theory of relativity by qgroessl on 11-16-2005 at 02:03 AM

quote:
Originally posted by superjugy
if you go to speed of lght, nothing will actually happens to you, because the light itself travels at speed of light and nothing happens to it.

You can't go to the speed of light... Light will always be traveling just as fast away from you whether your standing still, or running at 5 miles per hour.

quote:
Originally posted by Underlord
The only thing that can travel faster than light is space. In a black hole space is being sucked in faster than light travels, so light itself cannot escape. Very simple explination.

Einstein also concluded that gravity was not a force but a warping of space and time. Light itself is susceptible to gravity.

Einstein might have concluded gravity was not a force, but really it is... Gravitational forces are technically forces. If the force is so great that light cannot escape it, then all it's really doing, is not allowing any light to be seen coming from it, stopping time.

quote:
Originally posted by superjugy
and as far as i know the black holes are formed when suns explode and die. nothing to do with speed of light. and for the spacetime, as far as i know it is like another dimension intead of having time and distance separeeted they are in just 1 dimension.

You are correct in saying how black holes are formed... But they wouldn't be they'd be just, gone, if it had nothing to do with light. For it not to have anything to do with light, it would have to just dissappear. And the thing about the 1 dimension could be correct... it could be incorrect... We won't really ever know I don't think. I doubt it would be 1-dimensional... if anything it would be 4-D... Somehow...

:dodgy: this has gotten a bit off topic...

:refuck: and I'm not helping it much!
RE: RE: Theory of relativity by Voldemort on 11-16-2005 at 02:19 AM

quote:
Originally posted by SikStyles
wasnt the theory of relativity that when you sit in a room with a hot chick an hour seems like a second and when you sit on a hot stove a second seems like an hour

im not sure though.



Yes it is (or so i believe 8-))

quote:
posted by superjugy
here the science isnt very advance and in high school we dont learn this things

I am in junior high in mexico....an we are going to start monday with this :S


I read a few days ago that some scientists said that black holes where objects that had a very large gravitational force, and it will end... giving off everything it sucked in an unrecognizable way.... i wonder how would it give light off again...
RE: Theory of relativity by Underlord on 11-16-2005 at 02:29 AM

quote:
Originally posted by Supersonicdarky
not really, it's not faster than the speed of light, it has a huge gravity, thats why light can't escape


i also wonder if there is something non-physical that can travel faster than light... :S

And that gravity is pulling in the space around it faster than light travells. I said it was a simple explination :P.
RE: Theory of relativity by ShawnZ on 11-16-2005 at 02:41 AM

quote:
Originally posted by superjugy
E=mc2 means that any mass going to the square of the speed of light then it would transform into enrgy.


<shawnz> ANY MASS GOING THE SQUARE OF THE SPEED OF LIGHT
<shawnz> (WHICH ISNT POSSIBLE BECAUSE THE ONLY THING THAT TRAVELS AT THE SPEED OF LIGHT IS MASSLESS THINGS
<shawnz> (AND NOTHING GOES FASTER THAN THE SPEED OF LIGHT EXCEPT THINGS THAT ALREADY ARE))
<shawnz> but no
<shawnz> _IF IT EVER DID_
<shawnz> it would magically turn into energy
<shawnz> no TYPE of energy
<shawnz> it just magically turns into 'energy'
RE: Theory of relativity by ShawnZ on 11-16-2005 at 02:56 AM

quote:
Originally posted by damm-o

I read a few days ago that some scientists said that black holes where objects that had a very large gravitational force, and it will end... giving off everything it sucked in an unrecognizable way.... i wonder how would it give light off again...

They arent objects... and they don't give everything in it back out either
RE: Theory of relativity by qgroessl on 11-16-2005 at 03:05 AM

quote:
Originally posted by ShawnZ
quote:
Originally posted by superjugy
E=mc2 means that any mass going to the square of the speed of light then it would transform into enrgy.


<shawnz> ANY MASS GOING THE SQUARE OF THE SPEED OF LIGHT
<shawnz> (WHICH ISNT POSSIBLE BECAUSE THE ONLY THING THAT TRAVELS AT THE SPEED OF LIGHT IS MASSLESS THINGS
<shawnz> (AND NOTHING GOES FASTER THAN THE SPEED OF LIGHT EXCEPT THINGS THAT ALREADY ARE))
<shawnz> but no
<shawnz> _IF IT EVER DID_
<shawnz> it would magically turn into energy
<shawnz> no TYPE of energy
<shawnz> it just magically turns into 'energy'

Untrue... It doesn't magically turn into energy.... The mass contains all the engergy inside of it's nucleus. That's how nuclear energy is made... by splitting atoms. And atoms are the basic building block of all matter. And what superjugy said isn't completely true... E=mc2 simply means: Engergy, is the same thing as mass x the speed of light squared.


EDIT: ShawnZ was making fun of him ;)
RE: RE: Theory of relativity by Supersonicdarky on 11-16-2005 at 03:09 AM

quote:
Originally posted by Underlord
quote:
Originally posted by Supersonicdarky
not really, it's not faster than the speed of light, it has a huge gravity, thats why light can't escape


i also wonder if there is something non-physical that can travel faster than light... :S

And that gravity is pulling in the space around it faster than light travells. I said it was a simple explination :P.

but light can't travel than it already is (about 300000km/s), so it still travels at the same speed, but it bends because its sucked into the whole
RE: Theory of relativity by qgroessl on 11-16-2005 at 03:10 AM

quote:
but light can't travel than it already is

I'm thinking you're meaning either faster or slower?.... But anyways... I don't think it really bends... and sucked into the hole... if the force of gravity in a black hole is too great for a beam of light to escape... would it stand still?
RE: Theory of relativity by superjugy on 11-21-2005 at 06:17 AM

someone said that the you will never go fster than light, well how can u be so sure, light will always go at 300000 (dont remember how many 0) meters per second so i think if it has a finite speed and not an infinite speed then it can be rechable. how i dont know but it can be reachable. and for shownz that was making fun of me, @#%!& you, jk. but im really serious about what i said.


RE: Theory of relativity by DragonX on 11-21-2005 at 09:10 AM

Ok i read this whole thing, and now i'm a lil dizzy ;)

Now i'm not sure if it was said but one thing that has to be kept in ming is that the only reason why light goes the speed of light is because it has no mass - light is just a form of energy (photons - which have no mass - which are actually moving in a wave form which is called an electromagnetic wave). So anything with any mass, no matter how small will never go at the speed of light.

And like someone said, the faster you go the more energy you need .

The speed of light is the fastest possible speed. The reason is that, in order to accelerate an object, you need to use energy. The more massive (or "heavier") an object is, then the more energy it takes to accelerate it.  As an object moves faster, it appears to gain mass (or become heavier). We don't notice this in everyday life, because this effect really only becomes noticeable when you get very close to the speed of light, but scientists have measured and verified this theory in laboratory experiments. In fact, if an object gets very very close to the speed of light, it's mass goes up so fast that it can seem to be infinitely heavy! At this point, it is impossible to gain enough energy to accelerate the object any further.

And here's a twist to that theory! If 2 photons emitts from the same source, are not their speed, compared to each other, twice the light speed ? (In other words say a photon - in motion - releases another photon)

Simply put, No! This is a very strange thing about special relativity. Einstein's theory states that, no matter whether you are moving or standing still, light always moves at the speed of light. So, if you were on one photon and looking at the other photon, it would appear to be moving at the speed of light.

Mathematically, the ideas behind special relativity are very simple, and can be understood with basic algebra. However, a physicalunderstanding of what special relativity means is very difficult to achieve. I'm still not certain that I truly understand it; I just accept it as true (since repeated experiments show these theories are true).

So yea, here's my input on it :)


RE: RE: Theory of relativity by CookieRevised on 11-21-2005 at 03:09 PM

quote:
Originally posted by Underlord
The only thing that can travel faster than light is space. In a black hole space is being sucked in faster than light travels, so light itself cannot escape. Very simple explination.

Einstein also concluded that gravity was not a force but a warping of space and time. Light itself is susceptible to gravity.

Also as velocity increases so does mass. If velocity is at the speed of light (c) then mass is infinate.

As velocity increases time relative to the person experiencing the velocity slows down. If velocity is at the speed of light (c) then time relative to the observer stops.

Thus to reach the speed of light is impossible. Mass would be infinate (of the object travaling at the speed of light) and time would stop (from the point of view of the observer).
This is the only (simple) explanation (without wrong conclussions) I read in this thread (as I know it).

------

Thus the thing is, and what part of the theory of relativity is about, is if you would instantly start traveling at almost the speed of light, the observer who is watching you will see almost a still picture, nothing will move in his point of view. So if you are traveling for 5 years long at that speed, the observer wouldn't see this. And although you are 5 years older after that, the observer wouldn't have aged a bit (hence time is relative). Thus he wouldn't even have known you were gone. eg: if you would have traveled 50 years long and came back, the observer would instantly see you 50 years older (which would give him a heart attack for sure :p).

It has everything to do with point of view, hence "time is relative", it depends on who is observing who.

quote:
Originally posted by ShawnZ
quote:
Originally posted by damm-o
I read a few days ago that some scientists said that black holes where objects that had a very large gravitational force, and it will end... giving off everything it sucked in an unrecognizable way.... i wonder how would it give light off again...
They arent objects... and they don't give everything in it back out either
They are objects. Only objects with an extremely great mass (and because of that extremely small... they think). Black holes aren't all the same either, some have a greater mass than others.

Black holes not only absorb matter, they also emit stuff. And that is exactly one of the ways to know where a black hole is. Black holes burst out radiation beams.

quote:
Originally posted by groessl35
But anyways... I don't think it really bends... and sucked into the hole... if the force of gravity in a black hole is too great for a beam of light to escape... would it stand still?
Yes, light will bend under the influence of gravity (this is also what is shown on the picture posted by Juzzi earlier in this thread). And this is how some measurements are done in space, how they know where massive objects are, etc... etc... This isn't theory or anything, this is a fact and is even used in (space)science to measure stuff.

Also, if the force of gravity in an object is too great for a beam of light to escape we (thus the observers) would see only blackness and call that object a black hole.
RE: Theory of relativity by .Roy on 11-21-2005 at 04:17 PM

Its also possible to slow the speed of light. Light travels slower according to what it has to go through. For example light going through air is faster then light going through water. So if someone can find a really THICK material, then they can slow the speed of light. For example you can be in a room and walk out of it, then go outside and look through the material and you can see yourself still in it.


RE: Theory of relativity by Chrono on 11-21-2005 at 04:22 PM

Another dodgy example: Let's say im standing here, while cookierevised is traveling at *almost* the speed of light (:P). Now let's say that Tasha and Calvin are standing still in my point of view and then they both jump at the same time. I, of course, see that they jumped at the same time (because we are in the same reference), while cookie, who's traveling almost at the speed of light, sees that they jumped at different times :p.


RE: Theory of relativity by .Roy on 11-21-2005 at 06:03 PM

Also i think its possible to see in the past.

If you look at a certain position and go faster then the speed of light, you will see things that happened before ( but in reverse).


RE: Theory of relativity by John Anderton on 11-21-2005 at 06:58 PM

quote:
Originally posted by Madman
It is impossible to go beond the speed of light because it would require an infinate amount of energy (or somthing like that).
Well ..... its basicallay proved by einsteins rest mass to velovcity mass equation

m = (m0) / (1-v^2/c^2)^1/2

Where m is you mass at velocity v
m0 is your mass at rest (that zero is a subscript ;))
c is the velocity of light

Thus as you velocity approaches the speed of light ... your mass becomes higher. You cant exceed the velocity of light cause well .... root of negative numbers are imaginary;)

So for any given case
v^2/c^2 <= 1

v <= c ;)

quote:
Originally posted by Madman
and it also covers "The faster you go the slower time goes".
Remember this example. If there are 2 identical twins. You tell one to stand on a planet and you tell the other to go at the speed of light till a star and comeback. If he comes back after one year by his his time ... his brother may have aged about 50 years ...
I dont have the mathematical proof for this, but this is what happens.

quote:
Originally posted by SikStyles
wasnt the theory of relativity that when you sit in a room with a hot chick an hour seems like a second and when you sit on a hot stove a second seems like an hour
:dodgy:
FFS. Dont spam in a serious thread.

quote:
Originally posted by ShawnZ
You don't transform into light if you go the speed of light. (You'll turn yourself into a black hole though)
Well ... NO YOU DONT
As i have already explained in Einsteins equation, as you velocity increases, your mass does too but this is only possiple as long as,
v < c
Once you reach the velocity of light, all your mass (the one that you had and the one that you had gained due to your velocity) gets converted into pure energy. No mass can exist at the velocity of light well except for protons is light (according to De Broglies Hypothesis / Dual Nature Of Light) [quanta (packets of energy; they dont have mass^o)) are a different story. They are energy]

And btw, speed of light isnt the fastest thing. Its been broken .... about 10 years back |-)

Well a few british scientists took a dark tube, made a small hole, let light enter and reflected it in one direction. Then from behind it the let a laser loose. They wanted to find the velocity of the laser under different laser. Note that this is a special type of laser. They noticed that under certain conditions the particles of the laser reached before that of light.

quote:
Originally posted by Underlord
The only thing that can travel faster than light is space. In a black hole space is being sucked in faster than light travels, so light itself cannot escape. Very simple explination.
Underlord, thats not true. I could explain if anyone wants to know ...

When a star burns normally there are two forces acting upon it, its high gravitational force acting inward (high because ..... it holds the whole planetary system together dont they) and the force due to contunious nuclear fusion (which acts outward)

It is the magnitude at of these forces that determines the size of the star at any instant. It remains like this for say a few kazillon years :P

Then eventually its low on fuel (hydrogen), it swells up for a few millenia (short time for starts pfft :P) cause the outward force due to nuclear fusion decreases due to a lower combustion rate. Then it runs out of hydrogen and its screwed cause it still has the same gravitational force but the outward force is zero. Thus it shrinks but as it does, its mass it still constant but its volume tends to zero
Density = Mass / Volume

Thus it has infinite density and thus infinite gravitational force. Thus not even light can excape it ;)

quote:
Originally posted by CookieRevised
They are objects. Only objects with an extremely great mass (and because of that extremely small... they think). Black holes aren't all the same either, some have a greater mass than others.
O.o
Their mass is the mass of the helium remaining from nuclear combustion !!! The gravitational force comes from their negligible volume and high mass.

They think ??? Who think ?? Do you mean i think :P

quote:
Originally posted by CookieRevised
Black holes not only absorb matter, they also emit stuff.
Wasnt that a huge controversy !!! Stephen Hawking was wrong and no one figured it out for what ... 40 odd years ??

There was this one guy in the atomic research center here (where i live) and he was saying all along that what stephen hawking said was wrong. Black holes need to emit stuff as well, but people asked him how dare he question stephen hawking and stuff .... for about 30-35 years he was tormented ..... finally when stephen hawking accepted his mistake this guy was vindicated :P
quote:
Originally posted by CookieRevised

Also, if the force of gravity in an object is too great for a beam of light to escape we (thus the observers) would see only blackness and call that object a black hole.
The perfect definition of a black hole :cheesy:
RE: RE: Theory of relativity by CookieRevised on 11-22-2005 at 01:11 AM

quote:
Originally posted by John Anderton
quote:
Originally posted by CookieRevised
They are objects. Only objects with an extremely great mass (and because of that extremely small... they think). Black holes aren't all the same either, some have a greater mass than others.
O.o
Their mass is the mass of the helium remaining from nuclear combustion !!! The gravitational force comes from their negligible volume and high mass.

They think ??? Who think ?? Do you mean i think :P
No, "they" (points finger to wierd scientists)... :p

Studies suggest black holes can have different masses. aka: it doesn't have  infinite mass at all, and it can be different from the other black hole. Black holes are not so "black", and perhaps not "holes" either. The volume and masses of black holes can't be measured per-se, it is done in theory and calculation, but even that theory (eg: when you reverse the formula of calculating escape velocity near the event horizon) suggests black holes have different masses. Heck, if you say it has infinite mass, many famous important theories wouldn't even work.

As for the size, that's also pure theory and done with calculation based upon current physicis as we know it. Thing is, these current physics don't apply 100% when dealing with such stuff. Also, a black hole is more than simply "the extremely small thing" which sucks everything in; as that is called the singularity in the middle of a black hole. One black hole can have a larger inner and/or outer event horizon than the other, meaning the gravity is different than the other, meaning the mass is smaller/greater. eg: a solar mass black hole has a radius of +-3 kilometers, a 10 solar mass black hole has a radius of +-30 kilometers, etc. And since this mass is close to infinite, but not infinite, the singluarity is also not infinite small, but can even also vary in volume. Hence you also have something called supermassive black holes with a life span of millions of times the lifespan of the universe and mini black holes with a life span smaller than the lifespan of the universe and as small as the sun.

quote:
Originally posted by John Anderton
quote:
Originally posted by CookieRevised
Black holes not only absorb matter, they also emit stuff.
Wasnt that a huge controversy !!! Stephen Hawking was wrong and no one figured it out for what ... 40 odd years ??
yeah but even Stephen Hawking said they emitted stuff. The emittion I talk about is the single radiation beam comming from the polar axis from black hole as it absorbs energy/matter, almost like a pulsar. Not about the radiation discs and other stuff which is emitted from the material itself sucked in.

EDIT: turns out the stuff which is emitted and which I meant is called Hawking-radiation :P

[Image: fictional_Black_Holes_1__Cham.jpg]

Ps: [self-split] Theory of relativity
Edited: added url to image
RE: RE: Theory of relativity by Underlord on 11-22-2005 at 05:49 AM

quote:
Originally posted by John Anderton
quote:
Originally posted by Underlord
The only thing that can travel faster than light is space. In a black hole space is being sucked in faster than light travels, so light itself cannot escape. Very simple explination.
Underlord, thats not true. I could explain if anyone wants to know ...

When a star burns normally there are two forces acting upon it, its high gravitational force acting inward (high because ..... it holds the whole planetary system together dont they) and the force due to contunious nuclear fusion (which acts outward)

It is the magnitude at of these forces that determines the size of the star at any instant. It remains like this for say a few kazillon years :P

Then eventually its low on fuel (hydrogen), it swells up for a few millenia (short time for starts pfft :P) cause the outward force due to nuclear fusion decreases due to a lower combustion rate. Then it runs out of hydrogen and its screwed cause it still has the same gravitational force but the outward force is zero. Thus it shrinks but as it does, its mass it still constant but its volume tends to zero
Density = Mass / Volume

Thus it has infinite density and thus infinite gravitational force. Thus not even light can excape it ;)

I know how a black hole is formed. My explination wasn't meant to be inconceivably complex. Also it isn't possible for something to have "infinite" density. This would break the laws of quantum mechanics. The volume of the object is almost negligible, but it is there.

quote:
Since light has no mass how can it be trapped by the gravitational pull of a black hole?

Newton thought that only objects with mass could produce a gravitational force on each other. Applying Newton's theory of gravity, one would conclude that since light has no mass, the force of gravity couldn't affect it. Einstein discovered that the situation is a bit more complicated than that. First he discovered that gravity is produced by a curved space-time. Then Einstein theorized that the mass and radius of an object (its compactness) actually curves space-time. Mass is linked to space in a way that physicists today still do not completely understand. However, we know that the stronger the gravitational field of an object, the more the space around the object is curved. In other words, straight lines are no longer straight if exposed to a strong gravitational field; instead, they are curved. Since light ordinarily travels on a straight-line path, light follows a curved path if it passes through a strong gravitational field. This is what is meant by "curved space," and this is why light becomes trapped in a black hole.

From this one could conclude that space is falling into the black hole.

There is more than one way to see things. Everything isn't black and white.
RE: Theory of relativity by cardshark on 11-22-2005 at 06:32 AM

The biggest problem with defining things like black holes is that there is no true way to measure it and test to see where everything that is taken into a black hole ends up. For all we know, everything that goes into a black hole ends up in another dimension. Until we are able to travel into a black hole and come back out without being destroyed or lost forever, we will never truly know what happens when something enters a black hole.

The reason that a black hole is "black" is because of the lack of light allowed to be maintained in the area. It has no true color, but we (humans) visualize black as the absence of light and color.

As for the speed of light, there are many theories that may or may not apply. Again, the biggest problem is the lack of a proper ability to test those theories. For all we know, there could be a way to circumvent the speed of light by "stepping" out of this dimension/reality/whatever at one point and "stepping" back in at another. Though I read about the theory in a sci-fi novel (Orson Scott Card's Children of the Mind) I think it's something that is entirely possible given the nature of the cosmos as we know it (if you want a more detailed explaination, let me know or check out the book for yourself).

I'll stop there for now because my head hurts and I could ramble on about this subject for hours. :lipsrsealed:


RE: Theory of relativity by John Anderton on 11-22-2005 at 06:57 AM

quote:
Originally posted by Underlord
Everything isn't black and white.
Thats the best way to put it imo :P
We need a lot more research into such stuff. I would have loved to take up such subjects at university :P

Where did you get that quote from ?? I wanna read more :D

You know whats coincidence. Last night i was thinking of the same thing whilst comming home .... even before i saw this thread :|
freaky !!!

Anways, i think its kinda related to this topic cause i am gonna ask something about the 4th dimension.

Well we can only percieve life in 3 dimensions. We can sense the 4th dimension but we cant actually see it or travel through it.
Consider an ant or well .... a common house gecko (lizard) which can see everything in 2 dimensions .... it knows only 2 dimesions viz length (forward - backward axis) and bredth (left - right axis) it doesnt know anything about the height (up - down) axis.

Now assume it is walking on a ceiling and it falls down and lands on a baloon floating at the center of the room. Now where ever it goes, it cant escape since it has no idea that this is a baloon and he is above the ground (or below the ceiling) since he doesnt have a sence of height.
If there was a second gecko on the ceiling, how much ever he may try, he cant find the 1st gecko. See my point. We as humans can clearly see whats happening but the geckos wouldnt understand whats going on.

Consider our case, what if we managed to come in a similar condition. If one man goes into such a "positon" then we would nto be able to find him simply cause "time" isnt a dimension we can travel in.
So we as humans cant understand whats going on but there may be a higher species (imagine there are :P) that can see whats going on cause they percieve the world in 4 dimensions.

So how can we imagine what time looks like ?? I mean, you can see 3d stuff. what if you could see stuff in 2d then you could know what you are missing, the sence of depth that your eyes provide in everything (photos arent exactly 2d are they ?? you can still make out which friend of yours is standing in front and whos at the back. Im saying you should see both your friends in a picture standing side by side even though one is closer to the camera)

Then could you imagine what the time axis looks like ??

PS: Does anyone know that east asian (Japaneese or korean i think) kinda scientist who has done a Phd in Theoretical Physics and keeps comming on the discovery channel from time to time. He is simply amazing :| I think he got his Phd from MIT ^o)
RE: Theory of relativity by emit on 11-22-2005 at 02:35 PM

One thing to dispute here: black holes are NOT objects.
In the loosest possible terms a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull. Basically this mass concentration has an escape velocity greater than c, so not even light can escape. The idea of such a mass concentration that even light could not escape from originates with Laplace in the 18th century, then straight after Einstein's theory of special relativity Karl Schwarzschild managed some hypothetical solutions to the equations that described such an object. It wasn't until the 1930s that people thought "wow, these things might actually exist" - Oppenheimer, Volkoff, Snyder were the main researchers. They showed that when a sufficiently massive star runs out of fuel, it is unable to support itself against its own gravitational pull, and it should collapse into a black hole. That's as far as you can take it with special relativity, to advance you have to consider general relativity (the harder version).
In general relativity, gravity is a manifestation of the curvature of spacetime. Massive objects distort space and time, so that the usual rules of geometry don't apply anymore. Near a black hole, this distortion of space is extremely severe and causes black holes to have some very strange properties. In particular, a black hole has something called an 'event horizon.' This is a spherical surface that marks the boundary of the black hole. You can pass in through the horizon, but you can't get back out. In fact, once you've crossed the horizon, you're doomed to move inexorably closer and closer to the 'singularity' at the center of the black hole.
It is this singularity that is, in essence, the black hole. At the singularity our laws of physics no longer apply, the singularity cannot be considered an object at all. In conclusion a black hole consists of this singularity and the event horizon... a region of space. Not an object. Even the event horizon is not as well defined as you would think, due to Hawking's solution of the Black Hole Information paradox.
A note on what is emitted from a black hole: only one thing is emitted, Hawking radiation. The laws of quantum physics state (simplified :p) that the information emitted, when a black hole evaporates, about the matter inside the black hole can never be completely wiped out. Hawking's 1976 black hole model (whereby a black hole starts losing mass as soon as it has formed via radiating energy) showed that the data was totally destroyed, thus creating the paradox. Hawking's argument was that the intense gravitational fields of black holes somehow unravel the laws of quantum physics. In essence, Hawking's new black holes now never quite become the kind that gobble up everything. Instead, they keep emitting radiation for a long time, and eventually open up to reveal the information within. They also, unlike classic black holes, do not have a well-defined event horizon that hides everything within them from the outside world. Hence the nont-well-defined event horizon. This is the only emission from a black hole.
There are two indirect ways to detect black holes: x-ray binary systems and mass measurements on the centres of galaxies.

Edit: There is a further solution to black holes via string theory but it's hella complicated and I don't have the patience to explain it. :p


RE: RE: Theory of relativity by CookieRevised on 11-22-2005 at 06:37 PM

Ok, going into a bit more detail now :p

quote:
Originally posted by Time
One thing to dispute here: black holes are NOT objects.
In the loosest possible terms a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull.
(...)
At the singularity our laws of physics no longer apply, the singularity cannot be considered an object at all.
Since the singularity has a mass it can be considered an object; a quantum mechanical object.

quote:
Originally posted by Time
They showed that when a sufficiently massive star runs out of fuel, it is unable to support itself against its own gravitational pull, and it should collapse into a black hole.
Yes and no.

Certainly not all stars collaps in black holes at all. It is very rarly that it does.

You can devide stars in roughly 2 categories:

1) Stars with masses equal or smaller than +-10 times the mass of the Sun.
2) Stars with masses greater than +-10 times the mass of the Sun.



When a star with a mass equal or smaller than +-10 times the mass of the Sun cools down, and thus is ending its "life cycle" it gets bigger and bigger up to a red giant.

When growing it also looses layer after layer of material. When the last layer of material is emitted only the core remains. This emitted (last) layer in space is called a Nebula.

After that the core implodes into itself and is crushed down to a white dwarf (+-size of the earth).

When the density of the white dwarf is large enough, this core will on his turn implode and will cause such a shockwave that all material surrounding it and including the core is destroyed, this is called a nova or super nova type 1. Nothing will remain.

When the density of the white dwarf isn't large enough, the white dwarf will turn into a stable white dwarf and nothing will happen anymore.



When a star with a mass bigger than +-10 times the mass of the Sun cools down, and thus is ending its "life cycle" it gets bigger and bigger up to a red or blue supergiant.

Again this supergiant will eventually cause a super nova. But this time a super nova type 2. The core of the star will not be destroyed, instead it will be crushed down to a neutron star (+-10km).

When the neutron star spins fast enough, it will become a pulsar. Again nothing further will happen, although the gravity is extremely large, the rotation prevents it from further imploding.

But when it doesn't rotate fast enough and has a big enough mass, the gravity wins and only then will it turn into a black hole as there is no or not strong enough anti-gravity force to prevent it.



quote:
Originally posted by Time
In particular, a black hole has something called an 'event horizon.' This is a spherical surface that marks the boundary of the black hole. You can pass in through the horizon, but you can't get back out. In fact, once you've crossed the horizon, you're doomed to move inexorably closer and closer to the 'singularity' at the center of the black hole.
Yes and no.

A black hole has an outer event horizon and an inner event horizon. The outer event horizon is the space where you will begin to feel the gravitational pull of the black hole. The inner event horizon is the region you can not escape anymore as the velocity needed to escape that must be greater than the speed of light.

It is this inner event horizon which is called the Schwarzschild region.



One black hole isn't the same as the other black hole and they can have different masses. The mass can vary from a few solar masses up to the combined mass of millions of galaxies put together.

And because of the mass difference, also the sizes can vary from extremely small as with mini blackholes to massivly large as with super black holes.

Black holes can be divided into two main types, or rather their type of singularities:

1) A point singularity. This type of black hole is what most people think of as a black hole. The point singularity is formed from stationary, non-rotating matter; The black hole doesn't rotate. This is the blackhole associated with Schwarzschild.

2) A ring singularity. The rotating neutron star isn't crushed into a single point singularity but into a ring because of the rotation. Thus this type of black hole is formed from rotating matter. Space and time surrounding this singularity will be dragged around like a vortex.

And this last type is the interesting one, and the one which is predicted and prooven by Einstein's general relativity theory.

The general relativitly theory says and proofs that you could go into this ring singularity and when you will return you will return before the time you started going into the black hole.

Note that Einstein didn't liked this and was greatly disturb by this as this allowed for possible time travel!

Thus Einstein, together with Rosen, also calculated/prooved that this region within this ring singularity, can be interpreted as some kind of bridge to another spacetime and thus somehow connect different parts of spacetime. Subsequently, these are called Einsten-Rosen bridges or we know these better as wormholes.

Up until now, this theory is still not proven 100% wrong. Although the theory of Schwarzschild is one way to proof it wrong. Or rather only to proof that you can't actually travel thru the wormhole to the other universe, you would be stuck in the middle, but you could see the other universe though (The Schwarzschild Bubble and stuff). On the other hand, that same theory of Schwarzschild also allows for the use of negative mass matter which actually could keep the wormhole open to pass thru and thus create a stable Schwarzschild wormhole.

While this negative mass matter is strange and doesn't fit in our current physics (for 100%), we also know there are very exotic things going on when dealing with black holes and we know that there must be something to compensate matter as we know it (black matter, black energy, etc...) in other words: who knows... at least it isn't totally impossible.



quote:
Originally posted by cardshark
Though I read about the theory in a sci-fi novel (Orson Scott Card's Children of the Mind)
That theory is exactly Einstein's General Relativity Theory (well, that is: part of)

quote:
Originally posted by groessl35
But anyways... I don't think it really bends... and sucked into the hole... if the force of gravity in a black hole is too great for a beam of light to escape... would it stand still?
The light emitted from the black hole can't escape gravity and thus it is bend back to the black hole (think of a magnetic field, or solar flames which bend back to the sun), hence we can't see it.

Only when a person is sucked into a black hole and passes the inner event horizon, the observer who is watching will see the sucked in person as if he/she is standing still (forever).

quote:
Originally posted by .Roy
Also i think its possible to see in the past.

If you look at a certain position and go faster then the speed of light, you will see things that happened before ( but in reverse).

no, you wont. You would go so fast that the light emitting from those events will never reach you, aka you would see blackness.

quote:
Originally posted by John Anderton
quote:
Originally posted by Madman
It is impossible to go beond the speed of light because it would require an infinate amount of energy (or somthing like that).
Well ..... its basicallay proved by einsteins rest mass to velovcity mass equation

m = (m0) / (1-v^2/c^2)^1/2

Where m is you mass at velocity v
m0 is your mass at rest (that zero is a subscript ;))
c is the velocity of light

Thus as you velocity approaches the speed of light ... your mass becomes higher. You cant exceed the velocity of light cause well .... root of negative numbers are imaginary;)
yes, they are imaginary but that doesn't mean it can't exist or be used to develop further theories (heck the imaginary number system and imaginary algebra is teached in every school). And this is actually were the theory of Schwarzschild comes into play; together with white holes, his "bubbles" and wormholes.

RE: Theory of relativity by Tochjo on 11-22-2005 at 06:40 PM

quote:
Originally posted by John Anderton
quote:
Originally posted by SikStyles
wasnt the theory of relativity that when you sit in a room with a hot chick an hour seems like a second and when you sit on a hot stove a second seems like an hour
:dodgy:
FFS. Dont spam in a serious thread.
He wasn't. A famous quote from Einstein is
quote:
Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. That's relativity.

RE: RE: RE: Theory of relativity by emit on 11-22-2005 at 07:47 PM

quote:
Originally posted by CookieRevised
Since the singularity has a mass it can be considered an object; a quantum mechanical object.

No, it has infinte mass - beyond an object. Even the laws of quantum mechanics break down.

quote:
Originally posted by CookieRevised
quote:
Originally posted by Time
They showed that when a sufficiently massive star runs out of fuel, it is unable to support itself against its own gravitational pull, and it should collapse into a black hole.
Yes and no.

Hence, "sufficiently massive". The limit above which they do is called the Oppenheimer-Volkoff limit.
RE: RE: RE: RE: Theory of relativity by CookieRevised on 11-22-2005 at 08:20 PM

quote:
Originally posted by Time
quote:
Originally posted by CookieRevised
Since the singularity has a mass it can be considered an object; a quantum mechanical object.

No, it has infinte mass - beyond an object. Even the laws of quantum mechanics break down.
Revise the theories and their formulas which describe black holes and stuff related and which are used to calculate stuff concearning black holes. They all include M the mass of black hole. If it was infinite not a single formula concearning black holes would compute.

Black holes can have any mass, from the very small to extremely large.

Even the Schwarzschild radius, R, is calculated using M
R = 2*G*M/(c^2)

G  = Newton's gravitational constant
M = Mass of the object
c  = speed of light

If M would be infinite it would mean we don't even exist! Because if the mass of only 1 single black hole in the universe is infinite, it would mean we are inside its Schwarzschild radius aka inner event horizon, in other words we all would be dead!

Take "Cygnus X-1", this is a powerful x-ray source and it is calculated that it must be much much smaller than 1/100th of a light-second across, aka smaller than the size of the Earth. And because it also forms a binary with a blue supergiant "HDE 226868" whose mass is +-30 solar masses, they calculated that the source (a black hole) is about 7 solar masses, aka a very small black hole!

quote:
Originally posted by Time
quote:
Originally posted by CookieRevised
quote:
Originally posted by Time
They showed that when a sufficiently massive star runs out of fuel, it is unable to support itself against its own gravitational pull, and it should collapse into a black hole.
Yes and no.

Hence, "sufficiently massive". The limit above which they do is called the Oppenheimer-Volkoff limit.

Yes, but only for neutron stars. And the upper limit for the mass which a star can have is:
- for white dwarfs (Chandrasekhar mass limit): 1.4 solar masses (above that and they will explode into a nova, aka super nova type 1 (see previous post).
- for neutron stars (Oppenheimer-Volkoff mass limit): +-2 to 3 solar masses, but generally stays well below 4 or 5 solar masses. Again see previous post.

This means any neutron star which has a mass below 4-5 solar masses will turn into a pulsar and above 4-5 solar masses will collaps into a black hole. In other words, again, the mass of a black hole can vary greatly and is not infinite at all...

Also note that this mass limit only goes for the current mass of the star aka the mass of the white dwarf or neutron star, not for the initial mass of the star before it imploded; A star can start of as a 9x solar mass star and still end up as a stable red dwarf of 0.5 solar masses.