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The Disappearing Universe
StartsWithABang writes: "If everything began with the Big Bang — from a hot, dense, expanding state — and things have been cooling, spreading out, but slowing down ever since, you might think that means that given enough time (and a powerful enough space ship), we'll eventually be able to reach any other galaxy. But thanks to dark energy, not only is that not the case at all, but most of the galaxies in our Universe are already completely unreachable by us, with more leaving our potential reach all the time. Fascinating, terrifying stuff."
one of the allures for me (and i think a lot of people intrigued with cosmology) is how we can interpret the findings as a macrocosm for our own personal microcosm of awareness and being.
the fact that seemingly inherent in our physical universe is a doctrine of the futility of outward movement (vis a vis reaching a sense of completion or boundary), to me, points to the individual quest for seeking oneself by focusing internally.
Physics graduate student here, and I'd just like to bring something into context before any ./ readers begin an existential crisis.
We don't *KNOW* anything about the dark matter/energy hypothesis yet. They are not well accepted theories like (classical) gravity or electromagnetism, but rather the best answer to questions we don't have any other way of approaching.
Warning: if you subscribe too heavily to these ideas now, you'll be way, way off base later when science starts finding better answers to the accelerating universe and other open questions. This stuff is great for discussion about philosophy and science fiction, but it is far from well accepted science.
Actually this theory says the number of things that could terrify you is disappearing fast. So instead of being comforted by this fact, they are being terrified of running out of things that could terrify them. Universe does seem to be weirder than what you can imagine, indeed!
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
How can that be? I thought nothing could go faster than the speed of light.
Or does the universe not have to obey it's own rule?
We're talking about expansion of space itself, not about a body traveling in that space.
no, I don't have a sig
Much of the idea of wormholes came from the idea that universe might be spherical in topography --- like a hypersphere --- and a wormhole could poke through the hypersphere to create a shorter distance than even a line segment from Point A to Point B.
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question35.html
http://en.wikipedia.org/wiki/Shape_of_the_universe
But measurements are looking like the universe is flat.
You never know what scientific discoveries the distant future could hold, but at the moment it looks bleak for the concept of wormholes since the universe doesn't seem to be a hypersphere at all.
Priest: "Universe from nothing, no laws of physics, sped up time"+ huge discrepancies. Creationism? No. Big Bang Theory
This. They're already unreachable now. And until someone comes along and proves Einstein wrong, they're going to remain that way too.
SJW's don't eliminate discrimination. They just expropriate it for themselves.
Seriously. Dark energy is hypothetical.
Heard it all before. Earth is flat, humans flying is impossible, break the sound barrier and you die, yadda, yadda...
"I'm thinking wormholes, warp drives, hyper space."
All of which are are unproven theories. And could be proven to be impracticable (needing an energy the size of a star E stills equals MC^2) or impossible, or dangerous aka destroying the universe.
It may be the Speed of Light is the Speed limit that we cannot break.
In a world where Science Fiction is still fiction, and these wormholes, warp drives, and hyper space are meant as plot devices to move your characters into the story conflict of dealing with something alien. You find that these plot devices are made especially for weekly serial TV or movies with Sequels as you want to keep the same characters time and time again.
Now that said, it doesn't mean we should stop space exploration or trying to break the limits. Even if we could get a fraction of the speed of light say 1/10th the speed of light. We could travel our own solar system as well the sailors of old traveled the oceans. Generational ships can bring us to stars that are within 10 light years of year, and come back to earth without too much diversion of evolution.
Even without having to jump galaxies there is so much in our little neighborhod that we haven't explored.
As per Douglas Adams:
Space is big, I mean really big, you won't believe how mind boggling huge it is. You think it is a far way to the chemist? That is just peanuts to space, listen!
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
It's not that the thing itself is flying away from us at c, it's that all the space in between us and that thing is expanding. Naturally the further away it gets, the more expanding space there is between us and the thing, the faster the thing appears to be receding from us.
In this system nothing is moving faster than the speed of light but the effect is the same: a spacecraft trying to reach that galaxy would need to overcome all the expanding space between, and that would require a speed greater than c. In fact, at that point even light from that galaxy would not reach us anymore, putting it outside our cosmological horizon.
Disclaimer: I may not know what I'm talking about. This should really be in my sig.
Murphey's fighting Occam, and we're in the stands.
You can't move through space faster than c, but space can move or expand faster than c. The space between us and some distant galaxies is greater than c, meaning, we could never get to them, even at the speed of light. Some galaxies have been measured to have red-shifts past 2c. Even if you were a photon, they'd still be moving away from you at c, which is hard to understand because a photon does not experience time.
It's not really that fascinating or terrifying, though. "Based on our current understanding, we will never be able to reach certain galaxies." Ok, that's cool. We can't even reach another star system within our own galaxy at the moment, so traveling to other galaxies is a bit moot as is. We also know our understanding isn't complete, so it's entirely possible that something we don't know will allow us to travel to those galaxies.
Seriously, this doesn't feel like news. We've been working at the whole science and technology thing for what...ten thousand years or so? I say give it a million more and see where we are then, instead of cranking out sensationalist doom and gloom articles. Of course, all the doom and gloom articles tell you that we're not going to make it another decade, let alone a hundred thousand decades, so if you really feed into such things, then I'd say your outlook on the universe is far more terrifying than the article at hand.
Now I'll never find the missing socks
The problems are a bit deeper than "we don't have the technology to do it". If we would be able to break these theoretical speed limits, this would automatically imply we would also be able to travel through time or at the very least send messages into the past. That would create a whole bunch of problems for concepts like causality, free will, grandfather paradox, etcetera. Not entirely impossible, I agree, but unlikely nonetheless.
For Andromeda, just wait (very long term stasis recommended) it's comming at us, not sure it's a good thing.
Or Beta.
Perhaps he's a trifle more educated than you are?
Why, did he study custard and jelly with a minor in cream?
Wanna buy a shirt?
https://www.redbubble.com/people/stealthfinger/shop?asc=u
Seriously. Dark energy is hypothetical.
Heard it all before. Earth is flat, humans flying is impossible, break the sound barrier and you die, yadda, yadda...
If you don't understand the difference between a line of uninformed idiots who kept saying "You can't have a rocket in space because there would be nothing to push against", displaying complete ignorance of Newton's laws, and the limits which are the consequence of well-reasoned scientific models such as C being an absolute limit of material acceleration, then you flat out don't understand the difference between a scientific approach and simply drawing limits out of your butt.
I understand your reasoning, but I question the math. The time for light to travel from Earth to Andromeda is, essentially, zero (0) seconds. The time for humans to WATCH it do that is 2.5 million years. Recall the Twin Paradox where a person leaves Earth at near light speed, returns, and is way younger. The stay-at-home twin thinks the traveling twin has been gone a long time and the traveling twin says, "Hey. I just left!"
It little behooves the best of us to comment on the rest of us.
It's a bit more complicated than that. General relativity allows you to pick any reference frame, even one that is bent, stretched or distorted in some other way, and do your calculations in that reference frame.
You could pick a "normal" reference frame that obeys the special theory of relativity: speed of light constant everywhere, nothing can go faster, etcetera. Nothing wrong with that, but this turns out to be impractical: we have to pick some place to consider as the center of the universe (for example some place in our immediate neighborhood), and then find that the rest of the universe is moving away at very high speeds, approaching (but not exceeding) the speed of light. This means those galaxies are shrunk in the direction of their motion (Lorentz contraction) and time passes more slowly for them (time dilation). The further you "look" (the infinitely quick kind of looking which you can only do inside a theoretical model, not having to wait for light to get here so we can actually see stuff), the more things are shrunk and the slower time is ticking. At a distance of the speed of light ("c") times the age of the universe, things approach the speed of light and time is passing so slowly that the Big Bang is only just happening right now. In this way of describing the universe, with these coordinates the universe actually fits in a finite sphere around us.
That's a perfectly valid set of coordinates, but I think you'll agree it's not very practical. So physicists invented the cosmological model: imagine a bunch of clocks everywhere in the universe, flying at the same speed as the expansion of the universe (i.e. the same speed as average galaxies in that neighborhood) and ticking at whatever rate the local clocks are ticking at (not synchronized to ours). We define time at any place in the universe as being whatever is indicated by those clocks, not ours. So in effect we change the very definition of simultaneity, moving things from the future into today simply by changing the labeling. Also, imagine measuring sticks available everywhere in the universe, but just like the clocks flying at the same speed as the local expanding universe. To measure distances, we use those sticks instead of our own.
If we now measure everything using local (Lorentz-contracted) sticks and local (time-dilated) clocks, the universe looks completely different. It is truly infinite, the same age everywhere, and distant objects are no longer flat Lorentz-contracted pancakes but look the same as objects in our neighbourhood. Note that this is not a different universe, it's the same one but with different labels stuck onto objects.
Now, with this set of coordinates, it turns out that rays of light don't travel at a fixed speed "c" relative to us, but relative to the local clocks and sticks we used to define the coordinate system. It is still true that nothing can go faster than (local) light, i.e. you cannot overtake a ray of light, but a distant object certainly can move away from us faster than the speed of a ray of light in our neighbourhood. And if some alien over there were to try and shoot a laser beam our way, that light would never reach us because it is traveling towards us at the speed of light relative to the local "space" which is moving away from us faster, like a cosmic conveyor belt. Note that this conveyor belt is not real, it's just a product of our mathematical trickery refefining distances and times.
Of course you might wonder what happens to that alien laser beam in the first coordinate system, where rays of light all travel at the same speed relative to us. Well, in that system, the aliens don't exist yet because time in that part of space is moving very slowly (and has been moving slowly ever since the big bang). And since that part of space is still accelerating away from us ever faster and closer to the speed of light, local time comes to an asymptotic halt before the aliens ever get a chance to shoot that laser.
"Space itself" is just whatever we define it to be. By changing coordinates, we can move things from the past into the future or even into "never". It doesn't matter, it's just math(s), the end result is that we will never see that laser and we will never be able to reach that galaxy either.
"But not if our Universe is accelerating. If something is receding from us right now at more than 299,792.458 km/s—faster than light speed—and it’s accelerating too, how could anything reach it?"
Isn't c the upper bound of speed in our universe?
is the upper bound of acceleration through space. Think of it this way. acceleration of a point through the 3d graph of space IS limited to C. But the lines of the graph itself that define the 3d location of things in space are accelerating from each other... the farther they are from each other the farther they recede. There is no limit to that recessional velocity. You will get to a point where acceleration being fixed simply can't keep up with the recession, so you'll never reach those parts., nor will light from those parts reach your position. Vice versa applies here. We're receding at a speed greater than light from those areas. We're not feeling relativity effects because we're moving WITH OUR SPACE
I'm surprised that no one has yet mentioned the ultimate consequence of this recessional acceleration. Eventually the regions where this shows as an effect become smaller and smaller. Galaxy super clusters, then clusters, then galaxies fly apart, and that's when the effect really accelerates, shortly there after, solar systems, stars, planets, and ultimately even the atoms that once composed you and I fly apart as even as the recessional lines of space, accelerated by dark energy rip our observable universe down to a literal NOTHING. So the other end of the Big Bang becomes a Big Rip. Look it up.
The speed of light in a vacuum is always c. It doesn't matter if you're moving at 0.9c. If you shine a torch of light ahead of you, it will still move at speed "c".
What is meant here however is that there is no limit to how fast space itself can expand. So say we have two ends of a ruler 1 meter apart. After a while, space itself would expand meaning that the ruler will now be longer than what it was. There is no theoretical limit to how fast this can happen. It can be greater than c.
After a while, the space between the nucleus and electrons or within the nucleus itself will become too large, ultimately ripping apart for the fabric of reality itself.
Unreachable with current technology perhaps, but who knows about the future?
The future, Conan?
#DeleteChrome
> Unreachable with current technology perhaps, but who knows about the future?
Unreachable with current physics known to man kind. Not just current technology.
Hivemind harvest in progress..
Try Atkins.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
That's not right; only from the light's perspective maybe.. it's still "only" traveling at 186kmph a second, it's not truly instantaneous. And I've never heard of the theory that suggests that if a person leaves earth and travels near light speed he'll be younger when he returns. He might not have aged, but not younger... unless he actually exceeds light speed.
Probably it was some type of a typo where he meant the returning brother is way younger than the brother that stayed (as opposed to just being "way younger" as stated in the OP's poorly worded response.)
Also, and playing Devil's Advocate a bit more, when the OP wrote this:
The time for light to travel from Earth to Andromeda is, essentially, zero (0) seconds
I'm reading it as the time that light (or anything travel AT the speed of light) "experiences" traveling from Andromeda to the Earth (or pretty much from any point A to any point B) is zero because of time dilation. True, it will take 2.5 million years (when measured from the POV of an observer not traveling at relativistic speeds), and travel is not instantaneous, but the traveler itself will experience time at a complete stoppage when travelling at the speed of light (or falling down a singularity) regardless of having traveled one inch or the entire width of the observable universe.
No. That would be assuming you can go faster than the speed of light, without limits, which isn't the case.
Even if you were a massless particle, you would reach the speed of light in less than 1 year of accelerating at 1G, and then, you wouldn't be able to go faster.
Nope. GP was correct: note he said 30 years ship time You can accelerate at 1G indefinitely and you won't exceed the speed of light. You will asymptotically approach the speed of light, and time dilation will make the trip seem very short to the crew on board the ship.
Now calculate the reaction mass required.
pardon me. I get my science from xkcd, which recently stated:
Suppose there are 40 billion habitable planets in our galaxy, and every one of them hosts an Earth-sized population of 7 billion Ted Olsons.
There's your quadrillion. Are you a fan of hive minds?
There was a young lady named Bright,
Who could travel, faster than light.
She went out one day,
In a relative way,
And returned the previous night.
Red to red, black to black. Switch it on, but stand well back.
Best description I have is that dark energy isn't the explanation, it's the description of the problem.
At which point the rest of your post becomes pointless.
As you approach the speed of light, it takes more and more energy to go faster (actually this depends on the frame of reference). Regardless, you can continue to apply 1G of acceleration indefinitely, but not exceed the speed of light.
The 30 years or 80 years or whichever is ship time due to relativity, not observer time.
Well I can accept FTL and wormhole travel so I can enjoy a good story. But just because I can imagine such things, it doesn't mean I think they exist. In fact the reason I can accept FTL travel in a science fiction story is that I'm not imagining it too hard. If I tried harder, I'd end up bringing in Special Relativity. Then I wouldn't be accepting FTL or wormholes (which have their own paradox-generating aspects) as plausible within the story.
I'd like to believe that I could be immortal. I want to be immortal. Now that I have kids, I want *them* to be immortal even more than I want to be immortal myself. But just because I want something to be possible, doesn't mean the universe has to make it possible. Even if I want it really, really bad.
I don't think this makes me closed minded; if you could show me these things are possible I'd gladly believe. In fact I'll go further: my willingness to believe things I wish would happen are impossible makes me more open-minded than someone who refuses to accept the overwhelming preponderance of evidence.
For some people "open mindedness" means giving wishful thinking equal standing with evidence. This is especially true of science denying movements. Well, I don't accord wishful thinking much credibility. It doesn't mean I don't wish, I just don't expect those wishes to come true.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
Wrong on so many levels.
1) Yes, they are moving away from us at faster than the speed of light. This is well established.
2) As long as the photons reach a region of space receding at less than the speed of light, we can see these galaxies. Good info here
3) "And they fail to mention that they only way we're traveling through space is faster than light, some sort of weird quantum thing, by bending space, or via wormholes" None of which have been shown to exist. And there's some evidence that none of these options can exist.
There's no real center (as far as we know). You can pick any spot and consider that to be "the center" with everything moving away from that spot, but you can just as well pick some different spot.
Of course that's just one theory, with a truly infinite universe. It's perfectly possible that the universe is finite after all, or that it wraps around at some point. It certainly is very big.
No, those places are accelerating away from us much faster than 1G. Well, depening on the coordinate system you use to calculate that acceleration, obviously. But with cosmological coordinates, yes, way more than 1G and faster than the speed of light. In any case, you will never reach their speed no matter how fast you accelerate, since you can't go faster than (local) light and even light will never catch up with them. Even if you shine a strong laser at them, that light will never get there.
(Assuming our current theories about the inflation of the universe are correct)
As you approach the speed of light relativistic effects slow the passage of time.
At the speed of light, time cease to pass. Light in effect travels instantly from its perspective (in a vacuum, not sure what happens when its in a medium and slows down). We see the light move, but if you were a photon, your entire existence would be instantaneous from start to finish. Only an outside observer not moving at the speed of light would see light 'travel'.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
I propose building an engine which sucks in another universe from another dimension to burn as fuel. Though there may be ethical implications when using inhabited universes.
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