Poll: What will become of humanity in regards to the fate of the universe?
We will know how to escape to another one or to "go back" to the beginning of this one.
We'll live for billions of years until the universe ends.
We'll never get out of the solar system before we go extinct.
We'll never get off the planet before we go extinct.
I don't know.
Let's just keep trying to push frontiers, and if we figure out how to escape the eventual death of the universe, well then that's all fine.
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The Universe will eventually die - what do you think will become of us?
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22-05-2013, 01:32 PM (This post was last modified: 22-05-2013 01:50 PM by Adenosis.)
RE: The Universe will eventually die - what do you think will become of us?
(22-05-2013 12:51 PM)cjlr Wrote:  [1]Yeah, black holes don't have 'ends'. They are singularities.

[2]Common misconception #2 - black holes are 'stronger' somehow than other gravitational objects. Gravity operates the same regardless of what causes it (it being the warping of spacetime). Outside of a black hole's event horizon, it is a perfectly well behaved gravitational object. Yes, they generally ARE quite massive (they have to be, to last any length of time), but the gravitational attraction is no more than that of the object it formed from.

[3]So, if you passed the event horizon, you'd get a great show if you looked out. Assuming you went in feet-first... You'd be spaghettified (yes, that IS the technical term), but as you were drawn deeper in, time would dilate (general relativity, yo) due to the depth of the gravity well. So you could watch the universe's greatest light show, as matter and energy swirled in after you; you could watch the cosmos age above you... Though, it would also blueshift, so really the radiation would kill you (not that a bunch of other things wouldn't probably have already done so, in such a situation, of course).

And eventually you WOULD be crushed to death. And spit out as Hawking radiation (not literally, of course - merely that the energy emitted would eventually account for the additional energy you inputted by falling in).

No winning indeed.

[1] Assuming our theories are accurate.

[2] Yes gravity operates the same no matter what is causing it, but the force of gravity depends on the nature of the cause (mass and density). The gravity on earth causes an acceleration of 9.8m/s, mars is around 3m/s. The magnitude of the acceleration induced is what I meant by strength, which indeed does change, and can be considered stronger or weaker relative to other massive bodies.

You are right in saying that the mass of the black hole is identical to the dying star, but it's density is not. Hence why the black hole has an event horizon which nothing, even light, can escape, but the star did not.

Density plays a role in the force of gravity, (this next bit is somewhat speculation) and I would assume the density is inversely proportional to the range of the force. What I mean is that the force from a black hole should decrease more as distance from it is increased (relative to the star which formed it). So say our star spontaneously condensed and formed a black hole, we may not get sucked in, but instead drift off into space, because the black hole is so small, the force would decrease exponentially at shorter distances (inverse square field).

I'm guessing there is some kind of conservation here, as density changes the force is increased yet the distance decreases, and the ratio of the changes may be a constant. Who knows Tongue

Any way, my point is that it is not futile to speak of the strength of a objects gravitational influence. I hope that was coherent.

[3] You would not see the universe age because the light reaching your eyes is undergoing the same time dilation as you.

Although this light would be blue shifted (more and more the further down you get) and so, it is possible that what would kill you would be high energy gamma rays that tear you apart top to bottom before the black hole itself can tear you apart bottom to top. If the black hole is not near another star, the amount of light won't be sufficient to kill you before the black hole does, but if the black hole is part of a binary star system, then perhaps there would be enough photons to get the job done.

(22-05-2013 01:06 PM)kim Wrote:  Well, the real shit will start when our Moon drifts far enough away from us to cause problems - that's about a million years away. If we don't stop trying to kill each other, we might actually figure something out about what to do with that first nail in our planet's coffin. After that,(long after) well... our sun will swallow us. So, we're eventually fucked.

Is any of that going to be a problem for anyone? Drinking Beverage

Maybe I just haven't thought enough about it yet... But what's wrong with the moon floating off?

The tides caused by the moon are slowing the planets rotation (not much at all of course, but still), I say let it go. Be free moon!

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22-05-2013, 02:17 PM
RE: The Universe will eventually die - what do you think will become of us?
(22-05-2013 01:32 PM)Adenosis Wrote:  [1] Assuming our theories are accurate.

[2] Yes gravity operates the same no matter what is causing it, but the force of gravity depends on the nature of the cause (mass and density). The gravity on earth causes an acceleration of 9.8m/s, mars is around 3m/s. The magnitude of the acceleration induced is what I meant by strength, which indeed does change, and can be considered stronger or weaker relative to other massive bodies.

You are right in saying that the mass of the black hole is identical to the dying star, but it's density is not. Hence why the black hole has an event horizon which nothing, even light, can escape, but the star did not.

Density plays a role in the force of gravity, (this next bit is somewhat speculation) and I would assume the density is inversely proportional to the range of the force. What I mean is that the force from a black hole should decrease more as distance from it is increased (relative to the star which formed it). So say our star spontaneously condensed and formed a black hole, we may not get sucked in, but instead drift off into space, because the black hole is so small, the force would decrease exponentially at shorter distances (inverse square field).

I'm guessing there is some kind of conservation here, as density changes the force is increased yet the distance decreases, and the ratio of the changes may be a constant. Who knows Tongue

Any way, my point is that it is not futile to speak of the strength of a objects gravitational influence. I hope that was coherent.

[3] You would not see the universe age because the light reaching your eyes is undergoing the same time dilation as you.

Although this light would be blue shifted (more and more the further down you get) and so, it is possible that what would kill you would be high energy gamma rays that tear you apart top from bottom before the black hole itself can tear you apart bottom from top. If the black hole is not near another star, the amount of light won't be sufficient to kill you before the black hole does, but if the black hole is part of a binary star system, then perhaps there would be enough photons to get the job done.

[1] Well, yeah Big Grin. Isn't that implicit in everything?

[2] Outside the event horizon, gravity is gravity (I mean, obviously the effect is proportional to the masses and distances involved...). But that's just it; outside that, a black hole is the same as any large gravitational object (from the perspective of, say, a space traveller jetting by). Galactic black holes, yeah, they're the biggest things we know of, but stellar black holes are, gravitationally speaking, the same as stars.

If the sun was spontaneously replaced by a black hole (of equivalent mass) we wouldn't notice (except, the light would go out...). Gravity is an inverse-square relationship - but it is the distance squared to the centre of mass! For a star this is more or less the centre (they're pretty rotationally symmetric). For a black hole it is... the black hole (it's a singularity, so it doesn't have a 'size', in that sense, though it does of course have an event horizon, which is some calculable radius). We'd be the same distance from the same (centre of) mass - our orbital dynamics would be unperturbed.

Though, really, the orbit is about the joint centre of mass... but the sun is so relatively massive that it's, for all intents and purposes, the same thing as the sun's centre of mass. Earth-moon system, now, not so much (the joint com there is ~75% Earth's radius).

[3] Turns out I was doing this one backwards (don't do lazy relativistic calculations in your head, kids!). An outside observer would see you falling in forever (well, not quite really forever, since black holes have finite lifetimes...), since, the closer to the event horizon you are, the the longer it takes the light to escape (given that the event horizon is the point at which no light can escape, up until that point there will be some that does).

You see the end of all things only if you were juuuust outside a sufficiently massive black hole (and it would take effectively infinite amounts of energy expenditure to wait there for it!). Your lifetime inside (meaning, properly, the time from passing within a couple Schwarzschild radii until you hit the event horizon) the black hole is finite, and so there's only a finite amount of time for light to reach you.

Once you DO hit the event horizon then who knows indeed. Since by definition all physics breaks.
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22-05-2013, 03:08 PM
RE: The Universe will eventually die - what do you think will become of us?
The universe will get destroyed? This is an unproven if not false premise, I don't find it particularly feasible that the universe will actually end (or had a beginning.) while I obviously have no proof the universe always has been, there is no evidence for it having a beginning or end either.
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22-05-2013, 03:43 PM
RE: The Universe will eventually die - what do you think will become of us?
Ok I feel kind of dumb, I can be a real goof when it comes to ambiguous use of language, lets assume what is meant is something along the lines of "the universe becomes completely uninhabitable to life." in which case, the human species will most likely become extinct long before then.
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22-05-2013, 04:51 PM
RE: The Universe will eventually die - what do you think will become of us?
(22-05-2013 02:17 PM)cjlr Wrote:  
(22-05-2013 01:32 PM)Adenosis Wrote:  [1] Assuming our theories are accurate.

[2] Yes gravity operates the same no matter what is causing it, but the force of gravity depends on the nature of the cause (mass and density). The gravity on earth causes an acceleration of 9.8m/s, mars is around 3m/s. The magnitude of the acceleration induced is what I meant by strength, which indeed does change, and can be considered stronger or weaker relative to other massive bodies.

You are right in saying that the mass of the black hole is identical to the dying star, but it's density is not. Hence why the black hole has an event horizon which nothing, even light, can escape, but the star did not.

Density plays a role in the force of gravity, (this next bit is somewhat speculation) and I would assume the density is inversely proportional to the range of the force. What I mean is that the force from a black hole should decrease more as distance from it is increased (relative to the star which formed it). So say our star spontaneously condensed and formed a black hole, we may not get sucked in, but instead drift off into space, because the black hole is so small, the force would decrease exponentially at shorter distances (inverse square field).

I'm guessing there is some kind of conservation here, as density changes the force is increased yet the distance decreases, and the ratio of the changes may be a constant. Who knows Tongue

Any way, my point is that it is not futile to speak of the strength of a objects gravitational influence. I hope that was coherent.

[3] You would not see the universe age because the light reaching your eyes is undergoing the same time dilation as you.

Although this light would be blue shifted (more and more the further down you get) and so, it is possible that what would kill you would be high energy gamma rays that tear you apart top from bottom before the black hole itself can tear you apart bottom from top. If the black hole is not near another star, the amount of light won't be sufficient to kill you before the black hole does, but if the black hole is part of a binary star system, then perhaps there would be enough photons to get the job done.

[1] Well, yeah Big Grin. Isn't that implicit in everything?

[2] Outside the event horizon, gravity is gravity (I mean, obviously the effect is proportional to the masses and distances involved...). But that's just it; outside that, a black hole is the same as any large gravitational object (from the perspective of, say, a space traveller jetting by). Galactic black holes, yeah, they're the biggest things we know of, but stellar black holes are, gravitationally speaking, the same as stars.

If the sun was spontaneously replaced by a black hole (of equivalent mass) we wouldn't notice (except, the light would go out...). Gravity is an inverse-square relationship - but it is the distance squared to the centre of mass! For a star this is more or less the centre (they're pretty rotationally symmetric). For a black hole it is... the black hole (it's a singularity, so it doesn't have a 'size', in that sense, though it does of course have an event horizon, which is some calculable radius). We'd be the same distance from the same (centre of) mass - our orbital dynamics would be unperturbed.

Though, really, the orbit is about the joint centre of mass... but the sun is so relatively massive that it's, for all intents and purposes, the same thing as the sun's centre of mass. Earth-moon system, now, not so much (the joint com there is ~75% Earth's radius).

[3] Turns out I was doing this one backwards (don't do lazy relativistic calculations in your head, kids!). An outside observer would see you falling in forever (well, not quite really forever, since black holes have finite lifetimes...), since, the closer to the event horizon you are, the the longer it takes the light to escape (given that the event horizon is the point at which no light can escape, up until that point there will be some that does).

You see the end of all things only if you were juuuust outside a sufficiently massive black hole (and it would take effectively infinite amounts of energy expenditure to wait there for it!). Your lifetime inside (meaning, properly, the time from passing within a couple Schwarzschild radii until you hit the event horizon) the black hole is finite, and so there's only a finite amount of time for light to reach you.

Once you DO hit the event horizon then who knows indeed. Since by definition all physics breaks.

[1] True. Sleepy

[2] Hmm, this deserves some thought... You may be right, the center of mass would be the same, and therefore the curvature of spacetime around it might be identical.

[3] This also, I will ponder. I'm not sure if we would be able to see the accelerated aging of the universe in this hypothetical scenario.

Mmm.. Shall we continue this back and forth in pm's? I'd rather not fill this thread with my ranting, and this is (albeit slightly) off topic.

mysterics Wrote:The universe will get destroyed? This is an unproven if not false premise, I don't find it particularly feasible that the universe will actually end (or had a beginning.) while I obviously have no proof the universe always has been, there is no evidence for it having a beginning or end either.

Ok I feel kind of dumb, I can be a real goof when it comes to ambiguous use of language, lets assume what is meant is something along the lines of "the universe becomes completely uninhabitable to life." in which case, the human species will most likely become extinct long before then.

There will be a point when life will not be able to form (no abiogenesis occurances) because the stars will have used up all the fuel to 'burn' and without a source of energy the universe will essentially 'freeze'. But I do not think there will be a time when life will be unable to survive, if sufficiently advanced before the star fuel is lost.

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22-05-2013, 11:30 PM
RE: The Universe will eventually die - what do you think will become of us?
Perhaps one day, humans will build robots to which they can transfer their minds and live as long as they will. They will travel to other galaxies, and perhaps discover other sentient life.
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22-05-2013, 11:33 PM
RE: The Universe will eventually die - what do you think will become of us?
If the universe dies there's nothing left. The it'll explode again and start everything all over.


God is a concept by which we measure our pain -- John Lennon

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23-05-2013, 12:00 AM (This post was last modified: 23-05-2013 12:13 AM by Adenosis.)
RE: The Universe will eventually die - what do you think will become of us?
(22-05-2013 11:30 PM)zaybu Wrote:  Perhaps one day, humans will build robots to which they can transfer their minds and live as long as they will. They will travel to other galaxies, and perhaps discover other sentient life.

Honestly, I'm planning on this. It won't involve uploading my mind, I don't see how that could work. It would involve replacing every bit of someone with more stable bits. I imagine replacing each neuron with a synthetic counterpart, if you go one by one, at what point will you be lost? I suspect you won't. Which single neuron would be the cut?

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