Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: ShadowGorrath on May 19, 2009, 03:46:56 am
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Hi,
I need some info on this topic for school and all, so can anyone give me any cool pictures and info, maybe videos too, about this?
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Astronomy picture of the day (http://apod.nasa.gov/apod/)
Look in the archive, there's hundreds of pics in there. More than you'll ever be able to look at :P
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yeah, uh.. it's really, really big... yeah...
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http://www.atlasoftheuniverse.com/
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You think a walk down to the pharmacy is a long distance, but that's peanuts to infinity.
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http://teachspacescience.org/graphics/pdf/10000540.pdf
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/971124x.html
http://astro-canada.ca/_en/a4201.html
Some useful starting points :)
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If you don't want to go into all the "what is on the other side of the end of the universe?" argument, then the universe's size is infinity, basically that means it is unknown. People have tried to calculate the size of "our" universe using billion year old light, but then "what is over the other side?" comes into it.
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And then there's the question, 'does the Universe end at the outermost point of expansion from the Big Bang?'
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Current evidence suggests the universe is infinite and flat, which means if you keep traveling in a straight line, you'll never come back to your starting point. There is no 'edge', there is no 'farthest distance from the Big Bang' - because, remember, ALL POINTS IN THE UNIVERSE emerged from the Big Bang, so everything is equally distant from the 'center', because the center is everywhere.
At least, that's how it worked last time I checked.
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You think a walk down to the pharmacy is a long distance, but that's peanuts to infinity.
Couldn't resist adding the full and attributed quote:
Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
Douglas Adams
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People have tried to calculate the size of "our" universe using billion year old light, but then "what is over the other side?" comes into it.
Heh, this topic is always so much fun. My current view is that the (other side) question is invalid. Because "sides" and "edges" are just simplifications minds create to cope with the non-homogenous make-up of the universe. Its kind of cool: as tough as it is to think in terms of infinity, its even tougher to try and think in any other terms :D
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The best thing you can do is to forget the association to "expansion" in the terms we three-dimensional time travellers tend to think of it.
It's not as much expansion as it is emergence of space between stuff.
Current evidence suggests the universe is infinite and flat, which means if you keep traveling in a straight line, you'll never come back to your starting point. There is no 'edge', there is no 'farthest distance from the Big Bang' - because, remember, ALL POINTS IN THE UNIVERSE emerged from the Big Bang, so everything is equally distant from the 'center', because the center is everywhere.
At least, that's how it worked last time I checked.
Yeah, latest observations do seem to suggest that the space is flat, but we would do well to remember that we can't observe the whole universe, and cosmology is one of those branches of science where surprises still sometimes occur, so I wouldn't put it out of the group of viable options for universe to be finite but borderless (a contained geometry like the surface of sphere, torus or even möbius strip).
The problem I have with infinite and flat universe is that it doesn't agree with the principle of universe being homogenous and isotropic, simply because there is a finite amount of matter and energy*, which in infinite space could not maintain a static average density of stuff and the universe would not be homogenous any more. It would mean that at some point you start running out of stuff and that would also imply a direction to the center point, which should be detectable as stuff moving away from a certain point rather than away from everything.
A finite, contained geometry feels a lot more intuitive to me. Of course my intuition has been wrong previously. However, when considering the most recent results in cosmology, I would suggest taking them with a grain or few of salt. We don't even really know how gravity works yet, and it's pretty important in cosmology to know that... amongst other things.
Most recent scientific results are all good and well but it's also good to keep the context in mind; gravity is the least known basic interaction of nature, and it is the strongest power in the universe in cosmological scale of things. I don't think we're well equipped enough on theoretical basis to have any finality in our knowledge of the cosmology quite yet. Particle physics, maybe, but macroscopic developement of the universe... we can make more or less educated guesses but their accuracy depends on the accuracy of models used in the interpretation of observations.
We know that the general relativity model of gravity fails at minuscule distances. Who says it can't give inaccurate results at very long distances either? The assumptions of dark matter for example rely entirely on general relativity model of gravity being accurate in galactic scale. But instead of looking at an observation that seems to contradict with the theory, cosmologists have assumed the theory to be correct and add hidden variables (dark matter and dark energy, namely) to explain the observation.
For all we know, gravity could work a bit differently in galactic or intergalactic scales than it does in solar scale. After all... doing exact measurements is sort of difficult, isn't it?
For the record - I know dark matter seems to be viable explanations to the behaviour of rotating galaxies**, but I'm just saying that from entirely empiric point of view, the introduction of dark matter (without further supporting observations) seems not unlike putting a "here there be dragons" text on unknown regions of map, or saying that the dragons make things happen this way...
*Of course you can consider that universe actually has infinite amount of energy but then you're getting into a thermodynamic can of worms that will likely eat you alive... How's about infinite entropy? :shaking:
**For the uneducated - observations of spiral galaxies have been somewhat puzzling because they seem to be rotating too fast for their apparent size, especially on the outskirts of the disk. Basically, if our best available model of gravity is correct, the outermost stars should be slinging into the void at the speed they are going - but they aren't.
So there is two options; either the model of gravity is somewhat wrong, or there's more mass around galaxies than meets the eye (literally). Purely assuming that there's some dark matter that you can't observe is a bit shoddy from scientific perspective; luckily, there have been some indirect observations of dark matter since, so it does seem like a viable explanation, but nevertheless it is a good example of what could possibly go wrong when the accuracy of theory is valued higher than observations to contrary.
Dark energy, on the other hand, feels somewhat dodgy in my opinion. :nervous:
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I think you make a good point about dark matter, and particularly dark energy, recent potential observations nonwithstanding. It's one thing to take a very good, tested theory and try to come up with workarounds for a few observations that seem contrary to it, but when these workarounds literally involve declaring that a full 95% or so of the universe is beyond our current ability to observe...any good scientist should at least take a massive pause and look at what the implications of that are. Part of me wonders if, somewhere down the line, we'll look back on dark energy in the same way that we look back on the "luminiferous aether" today.
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The Hitchhiker's Guide to the Galaxy is an excellent primary source. :nod:
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Sometimes I wonder if, rather than reducing the number of dimensions the Universe is expanding through, it might be better to consider expanding the number of dimensions. I've heard theories that the Earth is simply a 3-dimensional representation of a higher-dimension object, this is complete technobabble here, but is it possible all the alleged 'missing mass' could simply exist in places that it cannot be percieved?
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Sometimes I wonder if, rather than reducing the number of dimensions the Universe is expanding through, it might be better to consider expanding the number of dimensions. I've heard theories that the Earth is simply a 3-dimensional representation of a higher-dimension object, this is complete technobabble here, but is it possible all the alleged 'missing mass' could simply exist in places that it cannot be percieved?
I think you've hit the problem pretty accurately. I wouldn't be surprized if the string theory's dozen+ dimmensions was still short of reality.
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While it's not against forum rules to post threads like this, and everyone here is nice enough to help; try doing your own research some time. You'll learn more and it's less similar to getting everyone here to be your lackey :p
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Anyone given some thought to Homer Simpson's theory of a doughnut shaped universe?
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Mmmmmm.... Doughnuts.....
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While it's not against forum rules to post threads like this, and everyone here is nice enough to help; try doing your own research some time. You'll learn more and it's less similar to getting everyone here to be your lackey :p
I almost flipped out over this post, then remembered that this basically started as SG asking us to do his homework for him. In which case, I agree with you. :p
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Eh. . . No. I just asked for some images and info that I couldn't find. I'll still have to get the needed info out of what you posted, translate it and make a presentation. Thanks for the help.
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Remember how long the motion of planets had to be observed that the orbitual movement relation became apparent? Galaxies have not been observed that long. It is kind of interesting that the rotation speeds of the galaxies is explained by saying there is dark matter/energy rather than considering that the theory must be wrong.
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I don't think they think that "dark matter" is any specific stuff, but more like, "we don't know what this is, but it has a measurable and quantifiable gravitational pull on these stars, so we'll call it 'dark matter' as a placeholder"
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By the way, by looking at the Wikipedia page about unsolved problems in Physics, one tends to feel that what they are talking about (especially in cosmology) is more Mathematics than Physics. I personally dislike quite a lot of talk about symmetry-something nature of something. However, there are then some more interesting problems like the glass transition point, turbulence and sonoluminescence.
What I don't understand is that how can the cosmology researchers do their job while fully understanding they will most likely never see their theory tested within their life time?
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By the way, by looking at the Wikipedia page about unsolved problems in Physics, one tends to feel that what they are talking about (especially in cosmology) is more Mathematics than Physics. I personally dislike quite a lot of talk about symmetry-something nature of something. However, there are then some more interesting problems like the glass transition point, turbulence and sonoluminescence.
What I don't understand is that how can the cosmology researchers do their job while fully understanding they will most likely never see their theory tested within their life time?
They can test a lot of things when the LHC is online.
And physics is mathematics. The problem of symmetry breaking comes up all the time in day-to-day life. For instance, let's say you have a bunch of water. It's fairly symmetrical on the molecular level. But when that water freezes, it must break symmetry and form into a crystalline grid.
That's exactly what happens to the universe as it cools down (in some models.) Symmetry is broken, causing formerly unified forces (gravity, EM, so on) to appear as different things.
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And physics is mathematics.
:eek2:
That's a pretty bold statement.
The problem of symmetry breaking comes up all the time in day-to-day life. For instance, let's say you have a bunch of water. It's fairly symmetrical on the molecular level. But when that water freezes, it must break symmetry and form into a crystalline grid.
This is exactly what I meant. The talk about breaking symmetry hides the underlying physics.
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I don't think I understand your objection, then.
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And physics is mathematics.
:eek2:
That's a pretty bold statement.
I prefer to think of their relation in terms of this (http://xkcd.com/435/), particularly the hover text. :p
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What would you guy propose astronomers do? There's not a lot that can be done in the field of astronomy while being closely attached to a star which disperses and distorts cosmic rays and particles. An even greater disadvantage to the field of astronomy is that the majority of the instruments are on earth. There's not much that can be done in astronomy right now except theorize stuff and think of clever ways to try to test them.
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www.universetoday.com
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What would you guy propose astronomers do? There's not a lot that can be done in the field of astronomy while being closely attached to a star which disperses and distorts cosmic rays and particles. An even greater disadvantage to the field of astronomy is that the majority of the instruments are on earth. There's not much that can be done in astronomy right now except theorize stuff and think of clever ways to try to test them.
[nitpick]I believe if you replace 'astronomy' with 'cosmology', then sure. Astronomy is a pretty huge field and there's boatloads of research being done these days. :)[/nitpick]
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.......copy.........paste........
(http://img38.imageshack.us/img38/1944/majoris.gif)
I just love the image really.
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It is a rather cool animation, truth be told.
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But the Canis Majoris is merely a pixel in this photo:
http://www.ee.columbia.edu/~shane/img/hst_galaxy.jpg
And to show how small the above is, here's this photo:
http://z-e-r-o.up.seesaa.net/image/Hubble_Ultra_Deep_Field_Black_point_edit.jpg
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But the Canis Majoris is merely a pixel in this photo:
http://www.ee.columbia.edu/~shane/img/hst_galaxy.jpg
And to show how small the above is, here's this photo:
http://z-e-r-o.up.seesaa.net/image/Hubble_Ultra_Deep_Field_Black_point_edit.jpg
You're totally right. The image I posted was bull****. You are the king, forever.
*yawn*
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Bah! All this is just pebbles if only 4% of the matter in the universe is actually observable.
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I prefer to think of their relation in terms of this, particularly the hover text.
I personally like that xkcd strip.
Personally I think that Mathematics and Physics are not the same thing. They are really not even on the same level.
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Oh one more thing about those symmetry thingies. First you would need to define what does "symmetry" mean in the case of basic forces. Saying it's the symmetry that is breaking doesn't really even describe the actual physical processes that happen during icing. That is actually a larger problem in the Universities nowadays, quite a lot of simple ideas that led to discoveries have been hidden under a pile of massive amounts of maths, starting from Mechanics. I don't mean that the Maths is unnecessary, on the contrary, you need to calculate numbers to be able to give estimates, but that many things are much more clear when one can actually see them happening.
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Physics is just a mathematical model that we invent to try and approximate reality. :nervous:
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Physics is just a mathematical model that we invent to try and approximate reality. :nervous:
Yeah, that's my view...and that the fundamental structures of the universe are mathematical.
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Physics is just a mathematical model that we invent to try and approximate reality. :nervous:
Yeah, that's my view...and that the fundamental structures of the universe are mathematical digital.
Fix'd.
Which is sort of high on a freaky-****-metre if you think about it... :shaking:
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Universe.exe has performed an illegal operation and will be shut down....
:nervous:
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Could black holes be caused by div by zero error in gravity.dll? :lol:
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The Universe running on Windows would explain a hell of a lot. :p
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Explains that thing about Gravity on Macro and Micro scales though, bloody rounding errors....
;)
Oh, and for something controversial:
[attachment deleted by ninja]
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Nah. That implies it's meant to be there and there is something wrong when it's not. :p
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Hehe :)
Well, maybe if there was a God, people wouldn't argue and kill each other so much over whether there was a God, because He wouldn't let them ;)
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Physics is just a mathematical model that we invent to try and approximate reality. :nervous:
Reality is just a physical model invented to try and approximate mathematics.
Here's proof. (http://en.wikipedia.org/wiki/Simulated_reality)
Hehe :)
Well, maybe if there was a God, people wouldn't argue and kill each other so much over whether there was a God, because He wouldn't let them ;)
He gave us free will so that we can do whatever the hell we want. At least until Judgment Day.
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He gave us free will so that we can do whatever the hell we want. At least until Judgment Day.
Odd, then, that there are so many different sets of rules, no? And not all of them promote Judgement day, of course, all the other rules are 'wrong', that's why people go around killing each other, for following the 'wrong' rules.
Interesting how that works out, no?
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Just so you know, the project won't happen. Thank you for the info though, and please keep discussing as it's quite interesting here.
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You think a walk down to the pharmacy is a long distance, but that's peanuts to infinity.
Depends... if you never start walking in the first place "because it's too far" you could argue the difference matters little because you will never start walking towards either anyways because it falls into the very same category of simply being "too far to bother". :g: :p