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HnR)hT
United States3468 Posts
On March 14 2010 22:57 ManBearPig wrote:Show nested quote +On March 14 2010 04:35 SpiritoftheTunA wrote:
The speed of light is a fundamental constant that's a property of the universe, and one important property of that speed is that nothing can travel faster. (except the spacetime fabric itself and entanglement-related information, apparently)
I am by no means a scientist, but I think taking some constant out of a theory and calling it a 'property of the universe' is pretty naive. I think it's more like a constant that Einstein needed to make his theory 'work' mathematically. There is, for example, an alternative relativistic mechanics theory (or whatever one might call it) developed by Poincaré, which does not need this constant. I do think it's a lot more complex and harder to use, and I think it wasn't quite able to explain the bending of light or something, so Einstein's theory is better. But this supports my point, I think, that taking a certain scientific theory and stating that it contains or directly describes 'properties of the universe' is quite naive and incorrect.
You are thinking about the speed of light in the wrong way. It is simply a conversion factor between the units of length that we use, which are arbitrary, and units of time. Since Einstein we know that length and time are equivalent in some sense, and it is natural to measure them in the same units. That's what is usually done in relativity, by setting the speed of light equal to one.
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On March 15 2010 02:21 Housemd wrote:Show nested quote +On March 15 2010 00:11 SkylineSC wrote:
how many of you are actually credible physicists in talking about inter galactic travel?
going to another galaxy is still a myth at this point. and life is even a bigger one. Dude, do you actually believe that they a trillion+ stars, a trillion+ galaxies and a trillion bunch of planets in outer space and we are the only ones out there....
Actually the trillion bunch of planets is already in our own galaxy, knowing the fact that we can already estimate the number of galaxies in the universe to be 500 billions. If we were really alone that would make 1 chance out of 500 billions trillions planets^^
We never really witnessed any kind of thing in the universe with such low probability rate. I mean your grandma would have more chances to live 1000 years!
So I would rather believe that life is a common thing in the universe.
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Thats pretty cool.. were deffintly not alone...
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Just a question of Einstein's theory of relativity, it states the that the universe is expanding FASTER than the speed of light.
If this is true, no matter how fast we go, we will essentially never be able to reach another body in outer space, right?
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HnR)hT
United States3468 Posts
On March 15 2010 03:09 Housemd wrote:
Just a question of Einstein's theory of relativity, it states the that the universe is expanding FASTER than the speed of light. If this is true, no matter how fast we go, we will essentially never be able to reach another body in outer space, right?
No, because cosmological recession velocities are utterly negligible for distances within our galaxy and nearby galaxies. In fact, objects that have superluminal recession velocities have distances in the gigaparsecs. So cosmology has no bearing on the possibility of interstellar, and even intergallactic travel.
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what the fuck is going on in this thread i dont even know. all the article said was that organic molecules were found on a nebula holy fuck gigaparsec the fuck?
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paulinepain, the most obvious argument is the anthropic principle: Suppose life is very, very improbable. Let's say it's so probable that we can only expect it to occur once in 10^30 planets. Then, that life that did occur could look around and say "hey, we're here, so that must mean there is life out there too."
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On March 15 2010 01:06 SkylineSC wrote:Show nested quote +I've taken 4 years of high school physics and 2 terms of physics here at Uni there is an expert on time travel if there ever was one
As a PhD student in astrophysics, I'd say that SpiritoftheTunA seems to know what he's talking about.
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misleading thread title
u_u can't wait for when we actually do discover other life (if it's in my lifetime)
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On March 15 2010 04:47 LuCky. wrote:
what the fuck is going on in this thread i dont even know. all the article said was that organic molecules were found on a nebula holy fuck gigaparsec the fuck?
Why would you take such an anti-intellectual stance just because your speculations were wrong? Science is a learning process, and that's a terrible attitude to have. Learn from your misconceptions, you shouldn't attach so much of your pride to speculative beliefs. If they're wrong, then so be it, you assumed something wrongly, life goes on. Don't pretend that tangential discussions are overreactions - what's this thread for if not discussing the article. Just because some people in this thread have more background on the subject doesn't mean you can't learn from it if you want to. Look stuff up! Wikipedia is a great resource. Don't have a preconceived notion and try to match the vocabulary in the articles to your definition - if you don't understand a part of the vocabulary, look it up! It's the best way to form an accurate perspective of physical reality.
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On March 14 2010 23:27 r4j2ill wrote:
lol humans looking for space travel when there are still shit messed up in our own world
lol paleo-indians migrating to the Americas when there is still shit messed up in Asia
lol homo sapiens looking to settle the rest of the world when there is still shit messed up in Africa
amidoinitrite?
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On March 15 2010 04:36 HnR)hT wrote:Show nested quote +On March 15 2010 03:09 Housemd wrote:
Just a question of Einstein's theory of relativity, it states the that the universe is expanding FASTER than the speed of light. If this is true, no matter how fast we go, we will essentially never be able to reach another body in outer space, right? No, because cosmological recession velocities are utterly negligible for distances within our galaxy and nearby galaxies. In fact, objects that have superluminal recession velocities have distances in the gigaparsecs. So cosmology has no bearing on the possibility of interstellar, and even intergallactic travel.
Rewording this, the rate at which the universe is expanding is most noticeable at the far ends of what we can observe, literally. Things closer to us, i.e. the orion nebula, aren't running away at any rate that could prevent us from getting to it (well at least not much more so than a static universe). If everything in the universe were expanding faster than the speed of light, as Housemd suggests, then we'd be ripped apart at the subatomic level pretty quickly. In fact, that's one of the possible death scenarios for the universe. http://en.wikipedia.org/wiki/Big_rip Oooh science
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How many people could we fit on the moon with population density equal to the US as a whole?
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On March 17 2010 03:24 Perseverance wrote:
How many people could we fit on the moon with population density equal to the US as a whole?
That's something you should be able to calculate yourself. I'll give you a formula, you look up the values.
amount of people on moon = surface area of moon * amount of people in the US / surface area of US
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United States43971 Posts
On March 17 2010 03:26 SpiritoftheTunA wrote:Show nested quote +On March 17 2010 03:24 Perseverance wrote:
How many people could we fit on the moon with population density equal to the US as a whole? That's something you should be able to calculate yourself. I'll give you a formula, you look up the values. amount of people on moon = surface area of moon * amount of people in the US / surface area of US
Why would you fit them on with an equal population density to the US? If you want them to live then no density will be thin enough because there's no water. If you don't want them to live then you could just pile them up across the entire surface several layers deep.
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Psh, it was like one in a over 9000 gazillion chances that we got life on earth with the molecules, not like theres going to be life on another planet just because we found some molecules needed for life.
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On March 17 2010 04:16 MuffinDude wrote:
Psh, it was like one in a over 9000 gazillion chances that we got life on earth with the molecules, not like theres going to be life on another planet just because we found some molecules needed for life.
I get your mathematically and scientifically-backed point.
Wait nope, lost it.
(if you're disagreeing with the title of the thread, it's been done at least twenty times already)
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On March 15 2010 01:53 SpiritoftheTunA wrote:Show nested quote +On March 15 2010 01:49 Housemd wrote:
This is interesting due to the fact that i having a conversation about it in class today with my math teacher.
HE says that the reason we can't travel the speed of light is due to the fact that this happens:
When we shoot a particle of light into a spectrum (or something, not quite sure) on the other end, the particle turns out to be TWO particles, each in a different location on some black paper they put as a "receiver". If we can find out what causes this, we can travel the speed of light to different galaxies. I think you're talking about this. http://en.wikipedia.org/wiki/Double-slit_experimentThis is an experiment that demonstrates the wave-particle duality of light. If you shoot a photon of light through two slits, and don't detect which slit it goes through, then the photon will act as if it went through both slits (even though it technically should be only one particle) and interfered with itself (as if it were a wave). This has to do with quantum mechanics, which I highly suggest you should learn in your academic future! To be honest, it doesn't have that much to do with the speed of light itself, but it's one of the things that got me interested in physics, so by all means, be open to the subject!
Is there a reason for the difference in behavior when it is observed vs unobserved?
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If it's unobserved then there is a range of places where it could be, like a probability distribution. Pretty reasonable... but the weird thing that quantum mechanics says that it doesn't just exist somewhere within the distribution, but it actually exists EVERYWHERE to some extent. It's spread out over space, just like a wave. (it's not exactly like this but its close enough) This means it can interfere with itself, etc. It doesn't just happen for light either, it works with electrons, protons.. technically it should even happen when you walk through a door but the wavelength involved is so tiny that you'll never see it.
When you observe a particle (or detect which slit it goes through), you force it to have a definite position so suddenly the probability distribution collapses down to a point. It's like flipping a coin - when it's in the air, it has probably H with 50% and probability T with 50%, but after you catch it and look at it, it's one or the other with 100% probability. Since the distribution is basically one point now, it behaves like a particle again.
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EPT
