[quote]spyoptic wrote:
Have you guys seen the History Channel special on the theories of parallel universes??? Well, I didnt understand a fucking thing but it was interesting to watch!
It doesnt matter, theres a hundred billion stars in our galaxy and a hundred billion galaxies in the observable universe.
traveling at the speed of light - it would take 10000 years to reach the nearest start alpha centauri. we’re fucking stuck!
in 15,000 years a new ice age will come, so hopefully we’ve found a new world by then.[/quote]
[quote]Pootie Tang wrote:
Well think about this…does and explosion really ever end? It has its physical manifestation i.e. fire. Then it has the after shock, how long does the after shock last does it ever stop? They say that when France was detonating nuclear weapons under water, that it took exactly 6 hrs for the soundwaves/shockwaves to circumvent the globe. Certain animals were able to sense the waves.
So if the Universe is in theory the result of a monumental explosion, who is to say the explosion ever ends? How do you get to the fringe of an explosion?[/quote]
However the universe was created (if you believe the Big Bang Theory) via an immense expansion of matter, not an explosion. It is infinitely expanding
[quote]sufiandy wrote:
spyoptic wrote:
Have you guys seen the History Channel special on the theories of parallel universes??? Well, I didnt understand a fucking thing but it was interesting to watch!
It doesnt matter, theres a hundred billion stars in our galaxy and a hundred billion galaxies in the observable universe.
traveling at the speed of light - it would take 10000 years to reach the nearest start alpha centauri. we’re fucking stuck!
in 15,000 years a new ice age will come, so hopefully we’ve found a new world by then.
[quote]ucallthatbass wrote:
I like physics and the universe, but admit that I don’t know enough to answer serious questions, I just screw round.[/quote]
That’s fairly obvious from some of the rubbish you’ve been talking about.
As President Clinton would say, it depends on what the definition is “is” is.
What “is” the condition at what we would call the furthest point in a given direction in which there is matter? Taking “is” as a present-tense verb.
We can observe the light that departed from that area more than 10 billion years ago. But does that show what it “is”? Most would probably say it shows what it was.
Let us say we build a ship that can travel at virtually the speed of light. Perhaps someday it will catch up with the matter in that area. (I don’t know if that is theoretically possible.) But that won’t happen, from the standpoint of Earth time, for billions of years. So is that an answer to what “is” the case there?
Yet on the other hand, from the perspective (if it can be said to have one) of a photon traveling between Earth and such a spot, the moments of departure and arrival are the same. So to a photon, the “is” of there is the same moment as the “is” of here. But the photon carries no information other than its frequency/wavelength/energy.
So far as the problem of catching up to the point in space where photons have travelled the furthest, this can never be done without exceeding the speed of light.
So it is not possible to outrun the size of the universe.
While that sounds reasonable enough to me, I don’t quite grasp what happens in the case of a contracting universe. Would matter traveling outwards, to its perception, at virtually the speed of light still nonetheless become closer and closer to the center of the universe? I suppose so but that is from supposition, not anything concrete. Performing general relativity computations is too hard for me.
[quote]Bill Roberts wrote:
While that sounds reasonable enough to me, I don’t quite grasp what happens in the case of a contracting universe. Would matter traveling outwards, to its perception, at virtually the speed of light still nonetheless become closer and closer to the center of the universe? I suppose so but that is from supposition, not anything concrete. Performing general relativity computations is too hard for me.
[/quote]
It would be the matter within the universe that is contracting, not the universe itself somehow getting smaller. Similarly, with an expanding universe, it’s not expanding into anything, there’s just more space (an analogy would be the way a bread loaf rises in an oven, you aren’t getting more bread, it’s just stretching out).
The really interesting thing about a contracting universe would be this bizarre idea: as the universe contracts, the available entropy increases unboundedly, and if you could send out self-replicating devices to every part of the universe (which would then return, having gathered all available information), you could effectively simulate the entire universe on a computer forever, even though the universe would end in finite proper time.
You could do a similar trick with a computer simulation running within a black hole (if that was somehow possible).
[quote]spyoptic wrote:
ucallthatbass wrote:
Well space and time are intertwined. The further away you move from earth (really should be the center of the universe) the further back in time you are going. After you get a certain distance away I forget the exact amount, galaxies become very sparse and are considered dead. Something like 420-440 billion light years away you reach a wall of radiation that science has yet to see beyond.
To a certain level the hugeness of the universe resembles the smallness of the atom. Once you get to a certain level of magnification (either zoomed in or out) they begin to look eerily alike.
This wall of radiation to me seems like that of cell wall. Maybe outside this wall are other cells or universes or maybe there is nothing. Sometimes I think about blackholes and how they are either massive destroyers of information (destroys everything that enters it) or transporters of information (wormhole). But, maybe the entire universe exists inside a blackhole with the wall of radiation being the event horizon. Now if the universe actual exists within a blackhole, the immense gravity alters space time so that anything falling in seems to fall infinitely from outside the blackhole. While within the blackhole it falls until it reaches the center, with the event horizon being the beginning of time.
Minds are now blown
thats all great, but the observable universe is 14 billion light years away. Thats why the estimate of the age of the universe is 14 billion years - we can’t see any further than that - the light hasnt reached us.
Atoms and the universe have similarities, but theyre both defined by two different laws. Physics main goal is a unification of both theories into one unified theory.
[/quote]
Key word: Observable.
Observable because there’s nothing beyond or because we can’t see beyond. We might not be technologically advanced yet?
Think about that.
[quote]jasmincar wrote:
trav123456 wrote:
Check out this gif
I feel small
Imagine If we where to find a planet like earth the size of the biggest star. That would be sick[/quote]
“Recent discoveries of some extrasolar planets known as “hot Jupiters” suggests that they are losing their light gasses in just such a manner, and will one day be lava-covered “terrestrial” planets of up to 15 Earth masses. Possibly these mark the largest sizes non-gaseous worlds can be.”
From a strict thermodynamic point of view, one can envision the universe as a “closed container”. If the volume of the container is infinitely large (infinite universe) then that would mean that the temperature of the gas inside the box would reach absolute zero, which is not the case (assuming law of conservation of mass-energy is obeyed). Then there is also the notion that space itself is actually a quantized quantity which I find interesting.
Infinitely expanding, at least I think. I always wondered what’s on the other “side” of the leading edge the universe. But seeing as how you’d have to be in a vessel traveling just above the speed of light since the beginning of the universe to actually be out there… of course we could always fold space. But we all saw Event Horizon and Dune and know that peeps who fold teh space are fucked up.
[quote]legendaryblaze wrote:
Observable because there’s nothing beyond or because we can’t see beyond. We might not be technologically advanced yet?
Think about that.[/quote]
No advancement in technology will make the light reach us any faster, sorry.
[quote]holguint123 wrote:
From a strict thermodynamic point of view, one can envision the universe as a “closed container”. If the volume of the container is infinitely large (infinite universe) then that would mean that the temperature of the gas inside the box would reach absolute zero, which is not the case (assuming law of conservation of mass-energy is obeyed).[/quote]
You’re talking about Kelvin’s heat death idea, presumably? In an expanding universe you would expect heat death. But it depends on the metric properties of space (the curvature), not the actual size.
[quote]JoabSonOfZeruiah wrote:
finite and unbounded(meaning expanding).[/quote]
Finite and unbounded does not imply expanding. Take the example of a loaf of bread in an oven. It is finite and bounded, but also expanding. Having a boundary means something different when you’re talking about things like manifolds, which you use to model space.
[quote]jasmincar wrote:
I guess in my ignorance that it has something to do with non-euclidan geometry (where the sum of all angle in a triangle is less than 180). Non euclidian geometry is like when you travel 10 miles south, 10 miles east then 10 miles north then you end up at the same place. Impossible? Not if you were at the north pole.
don’t go thinking I understand something about non-euclidan geometry
[/quote]
Essentially, the thing is that in euclidian geometry, parallel lines stay a constant distance away from each other. This happens in a flat plane. But if you imagine the Earth, and you take two lines (called great circles) going from the north pole to the south pole, around the Earth, then they will get further away from each other as you get nearer the equator. Similarly, if you draw two parallel lines on a saddle, they will get closer to each other at some point.
The key thing is that this property, and the property of having triangles with more or less than 180 degrees is somehow related to the curvature of the space. A flat space has constant curvature 0 (triangles have 180 degrees), a sphere has constant curvature 1 (triangles have > 180 degrees), and a hyperbolic space has constant curvature -1 (triangles have < 180 degrees).
[quote]Rational Gaze wrote:
legendaryblaze wrote:
Observable because there’s nothing beyond or because we can’t see beyond. We might not be technologically advanced yet?
Think about that.
No advancement in technology will make the light reach us any faster, sorry.
[/quote]
I mean that our cameras are not powerful enough to picture something beyond certain billion/trillion light years. So our universe might be larger than we think it is.
