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For, at the very least, the past several years the history channel as well as the BBC etc have had many shows discussing black holes, the big bang, supernovas etc.
The big bang as well as the unified field theory have been very interesting topics to me. Ive always wondered to myself, especially with the unified field theory...m theory, string theory, etc...none of which I claim to be some expert in, that if these scientists werent just inventing new things to fill gaps or wrong answers in their theories.
One such example that I feel is relevant to what is going on today is the topic of the "Aether".
http://en.wikipedia.org/wiki/Aether_theories
For a long time, at least from what I understand, many people believed in a substance called "Aether" that was invisible and or/undetectable that was used to propogate light (kind of like the Phlogiston that was thought to make materials flamible). People apparently tried to detect Aether but were unsuccessful and then Einstein came along and with relativity(special or general Im not sure) essentially showed that Aether was not necessary.
To get more toward the point, just recently more tv shows have been on and been advertising that there are more people nowadays latching on to the big bang theory being wrong. Now I am not schooled on the subject but Ive heard several arguements about redshift, the acceleration of the universe, dark matter, dark energy, etc. When I first heard of dark matter and dark energy, the skeptic in me just felt like it had to be bullshit. Higgs Bosons and the like just seem to have been thrown out there because what is observed does not match what is predicted.
I guess my Grand point is that does anyone else see the parallels between here and the Aether? I mean the Aether was just assumed to exist after a while until Einstein came along and then it was pretty much forgotten. Dark Energy and Dark Matter just seem like things that are thrown out there to fix equations. No one seems to wonder if there are problems in the equations we are using? I mean obviously there are predictions that occur that are correct (black holes, distortion of space, and a million more that I am not even aware of) but to me that doesnt necessarily mean everything is correct.
Id love to get some discussion going here, Im no expert in cosmology and astrophysics or anything but I know there are some well versed people on TL and Id love to here their opinions as well as the opinions from other "lay" people like me =)
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United States24613 Posts
I think the relationship between aether and dark matter is not as strong as you might think. Aether was proposed because (I think) all waves up to that point were found to propagate through a medium so it was reasonable to extrapolate that Electromagnetic waves such as light would have some medium also... and since we didn't think space had matter... maybe there was something else there to serve as a medium. I don't think aether had any bearing on equations though although I could be wrong about that.
Dark matter on the other hand is proposed to explain an unexpected mathematical outcome which is somewhat different than the aether example.
Also personally I find quasars interesting :3
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I thought the existence of dark energy was pretty concrete by now? I also haven't had anything formal in terms of learning about cosmology, but do take a very great interest in it. Dark energy is what fuels the expansion of the universe if I've come to understand it correctly.
If you're into this type of stuff you should check out The Black Hole War by Leonard Susskind. Also The Cosmic Landscape is good even though I haven't finished it yet.
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On June 28 2010 12:20 micronesia wrote:
I think the relationship between aether and dark matter is not as strong as you might think. Aether was proposed because (I think) all waves up to that point were found to propagate through a medium so it was reasonable to extrapolate that Electromagnetic waves such as light would have some medium also... and since we didn't think space had matter... maybe there was something else there to serve as a medium. I don't think aether had any bearing on equations though although I could be wrong about that.
Dark matter on the other hand is proposed to explain an unexpected mathematical outcome which is somewhat different than the aether example.
Also personally I find quasars interesting :3
I think some of the Electromagnetic equations had Aether in them.
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the big bang still holds so much clout because of the red shift, and blue shift effect- that one can see with the naked eye. It's this movement of light that points to an ever expanding universe. Thus if one were to think about this logically- the universe is bigger today than yesterday. If you go back and back and back- the universe and space itself would have at some point been infinitesimally small. Thus the big bang. I feel that the theory of relativity and space time is very accurate, because light is the measuring stick. Light is the only constant in our universe... basically i only have a layman's understanding of it all and i don't want to over step my bounds- but i think that the big bang is a very credible theory.
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Aether was put to rest my Michaelson and his xray experiments.
http://en.wikipedia.org/wiki/Michelson–Morley_experiment
I'm not an expert either, but I have the same "This sounds like hogwash" sentiment you have regarding dark matter and dark energy. At least that's the impression I got from my readings. The same sentiment is brought up for string theory too. A minority of physicists are saying string theory is a dead end, and that all the math and equations are justified by adding extra dimensions until the numbers make sense. That it's not real science. (I haven't read the books for a while, and I forget the titles  ). If you find anything interesting, let me know.
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I'm not educated on the matter either, but whatever. I do really like the subject tho, if you're into it, with a semi decent academic background I hightly recomend reading "the universe in a nuttshell" by Stephen Hawking, I did and it's reaaally good.
I don't really understand what you mean with the ecuation fixing and the ecuation's problems. We have a large set of ecuations that explain a very large amount of stuff that happens. Now when we observe a fenomena that isn't included in the model, what can we do? Saying that the model is wrong, and beggining from scratch will never work (you will fall back on your past ecuations eventually), you just have to change your ecuations so they adapt to all cases. That's how big abstract concepts emerge. The beauty of it is that it's still a theory, if in a certain situation our model and predictions work with it, we can use it.
I think the objective of fisics is to explain and predict what is and is going to happen. So yeah, if you assume there is a set of ecuations written somewhere that explain perfectly every single thing in the universe, you may consider our current ecuation to be.. yeah, flawed...
The thing is, the focus is diferent, science doesn't care about those "divine laws", we don't even know if they exist, if they change, if they're subject to a random element. We theorize about stuff that work for us, if we need abstract definitions to patch our ecuation, so be it, as long as it works...
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While there may seem to be similarities with what you're discussing at first glance, you have to take into account the actual research done behind both theories. Aether was more or less an assumption that helped explain things where as dark matter and dark energy aren't. The evidence of their existence is very easy to find and while it's not solid proof it is a very well-founded theory. If you take a glance at the equations of String and M-Theory you will notice there is a lot of missing energy in the universe that we can't see that HAS to be there, there is no way around it. We are able to deduce that it MUST be there and seeing as matter and anti-matter exist it isn't to far out of the realm of possibility. I don't really want to go into extreme detail as i'm tired but if you're interested in this read The Trouble with Physics by Lee Smolin. He goes in depth on the reasons why these theories could actually be wrong and what physicists are doing to prove or disprove it. Also, while a lot of shows are focusing on the Big Bang Theory and String Theory, there are also many more possible explanations and the book covers many of them. Many credible scientists don't agree with the Big Bang Theory, but as of right now there is no credible evidence to suggest it's not the most accurate theory at the moment.
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On June 28 2010 12:40 Sparkyrabbit wrote:
While there may seem to be similarities with what you're discussing at first glance, you have to take into account the actual research done behind both theories. Aether was more or less an assumption that helped explain things where as dark matter and dark energy aren't. The evidence of their existence is very easy to find and while it's not solid proof it is a very well-founded theory. If you take a glance at the equations of String and M-Theory you will notice there is a lot of missing energy in the universe that we can't see that HAS to be there, there is no way around it. We are able to deduce that it MUST be there and seeing as matter and anti-matter exist it isn't to far out of the realm of possibility. I don't really want to go into extreme detail as i'm tired but if you're interested in this read The Trouble with Physics by Lee Smolin. He goes in depth on the reasons why these theories could actually be wrong and what physicists are doing to prove or disprove it. Also, while a lot of shows are focusing on the Big Bang Theory and String Theory, there are also many more possible explanations and the book covers many of them. Many credible scientists don't agree with the Big Bang Theory, but as of right now there is no credible evidence to suggest it's not the most accurate theory at the moment.
I guess this is where my problem lies. From the little I understand string and M theory are purely mathematical and thats why many people have a problem with them. The better explanations ive heard for Dark Matter or Dark Energy are due to lensing and galaxies that are spinning not flying off into pieces(not that Ive done any of these calculations myself)
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the big bang still holds so much clout because of the red shift, and blue shift effect- that one can see with the naked eye. It's this movement of light that points to an ever expanding universe. Thus if one were to think about this logically- the universe is bigger today than yesterday. If you go back and back and back- the universe and space itself would have at some point been infinitesimally small. Thus the big bang. I feel that the theory of relativity and space time is very accurate, because light is the measuring stick. Light is the only constant in our universe... basically i only have a layman's understanding of it all and i don't want to over step my bounds- but i think that the big bang is a very credible theory.
Yea, but that's the issue. How far do you go back? How do we know at some point that the universe was infinitesimally small? How do we even know that the speed of light is constant? What if it's only constant in our current conditions, but it has different speeds in other areas of the universe? Big Bang just looks like a shot in the dark to me. HOw can you prove it?
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The Big Bang Theory predicted this. That and the significant red shift of everything far enough away from our galaxy is good enough for me. Sure there are unknowns, but the Big Bang Theory has no credible competition.
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United States10328 Posts
Dark energy is needed to explain the expansion of the universe. Otherwise the gravitational pull of the matter in the universe would make it contract. Expansion can be inferred from redshift and Hubble's Law.
And the big bang holds clout because of the cosmic microwave background, which is roughly isotropic and everywhere.
Grr I'll post more later when i get my laptop...
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On June 28 2010 12:14 Sadist wrote:The big bang as well as the unified field theory have been very interesting topics to me. Ive always wondered to myself, especially with the unified field theory...m theory, string theory, etc...none of which I claim to be some expert in, that if these scientists werent just inventing new things to fill gaps or wrong answers in their theories.
Yes, that's what scientists do. Look for gaps in their theories and things to fill them with. Then you make tests and see if/under what circumstances it holds.
For all science noobs: http://en.wikipedia.org/wiki/Scientific_method
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Let me try to help clear some things up. Dark energy HAS to exist. Why? Let's take a look at redshifting. When light travels through the universe while the universe is expanding the light becomes redder. If we look at the redshift in light from super nova's from stars farther away as opposed to those closer we can notice something almost chilling. The redshift is disproportional. How so? Well the redshift from the super novae farther have undergone lest redshift then those super novae closer to us in relationship to their distance. What can this possibly mean? Well simply put the only way this is possible would be if the universe were expanding faster now then it was earlier on in it's existence. What's causing this rapid expansion? We don't know. But we've named it Dark energy. We don't know what it is, but what we do know is that it influences how fast the universe expands. At our current ceiling of knowledge this is as far as we can understand, but it is the best that our scientists can come up with. Is it flawed? Yes. But it's what we know as of right now.
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I think the big bang theory is still pretty solid. As always, there are people who investigate alternative theories (which is a good thing!) but the vast majority of the astrophysics community still think its the best explanation so far, as it explains many observations.
I think there are some differences between the aether and the dark matter & energy explanations. The aether was something people just assumed had to exist, because light "had to" propagate through some medium. The reason people think dark matter exists is because observations say so. We know how galaxies should behave according to the currently known laws of gravitation, but they don't really behave as expected. On the other hand, if we add some unseen matter to the galaxies in some nice distribution, then they behave as expected according to the known theory of gravitation.
There are people who explore other options, such as modifying the theory of gravitation, but so far I don't think there have been many successful theories that can explain both galaxy behavior as well as other gravitational phenomena. It might turn out that we need to change the theory of gravitation, but I think the dark matter explanation is more likely.
Dark energy also originates from observation, i.e the observation of the acceleration of the expansion of the universe. In order for the universe to accelerate its expansion, we need a 'negative pressure' that operates on large scales, and this is what is called dark energy. I don't really know that much about it, I think its still very much speculation on what is causing it.
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Dark matter is significantly easier to explain. We know there are several parts of the universe where gravitational fields have been changed, however there is no visible mass, therefore where the mass that's distorting the gravitational fields are we have named to be dark matter. The dark matter basically, is just an invisible form of matter that is affecting gravitational fields. It is however like Dark energy INFERRED to be there, there is no proof. However, according to general relativity there are set laws to gravity and without something being there to distort gravity, theres no other explanation at the moment.
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Dark matter is not theoretical at all btw. Its just something that we have empirically measured but dont know clearly what it is.
Dark matter = something that we can measure the gravitational effects of but we cannot see (ie. it doesnt radiate towards earth).
When you have that measurements in front of you you can start theorising what could this stuff be... Smallish black holes, neutrinos, space dwarf fleets under cloacking devices? Then try to come up with something that rules other possibilities out.
edit: Ah sparky said kinda same thing while i was taking a shit, didnt notice before postin
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that if these scientists werent just inventing new things to fill gaps or wrong answers in their theories.
Yep, thats how it works.
Michelson/Morley said aether was no go.
Lorentz found the math to tie the gap.
Einstein gave a reason to the math. (And then some)
String theory describes A universe, we don't know if it describes ours.
Ideally there would be a way to test everything, but sometimes these things need to drift around for a few decades before they get put together in a meaningful way.
P.S. I think the speed of light is probably less constant than we think.
Why should the permittivity and permeability of free space be the same everywhere?
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Dark energy HAS to exist.
I think you guys are being a little cavalier.
An apple falling from a tree is an observation.
But the reason is not so clear.
Is it because all massive objects attract each other, or is it because massive objects distort space-time? (or is it just seeking its natural place?)
Dark matter/energy make an assumption about what would be needed in order for the observation to fit current theory.
But it could be that current theory just needs an overhaul.
P.S. And observation based on doppler shifting would get a little dicey if assumptions, like the speed of light being constant, aren't right.
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On June 28 2010 12:57 Sparkyrabbit wrote:
When light travels through the universe while the universe is expanding the light becomes redder.
That is correct.
If we look at the redshift in light from super nova's from stars farther away as opposed to those closer we can notice something almost chilling. The redshift is disproportional. How so? Well the redshift from the super novae farther have undergone lest redshift then those super novae closer to us in relationship to their distance.
That is incorrect. The wavelength of light increases as it travels through expanding space. The light from more distant stars travels through more expanding space and has a longer (redder) wavelength as a result.
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I am no expert here. Just a high schooler who enjoys astronomy.
No theories can be confirmed really. Take for example, gravity. This moment, it exists as the laws of the 'theory' indicate, but there's nothing to prove that in the next moment, it'll disappear. Sure, you don't expect it to happen, but you can't 100% predict it.
To try and figure out how the universe works, people make theories to try and explain it. No one knows if the theory of relativity is correct, we assume it is and base other observations from it. If we look back in history, there were so many 'theories' that were assumed to be 100% correct. The simplest example, the Earth is flat. It was just assumed that it was. Everyone believed it until it was proven false.
Until better theories come up to explain how the universe work, there's nothing much else we can do but rely on our current findings about dark energy and dark matter, etc, etc. Work with that or find a theory that explains everything we can observe better.
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Dark matter = something that we can measure the gravitational effects of but we cannot see
As a more concrete example, think of the solar system.
The planets on the farthest reaches travel at a slower rate than the ones near the Sun.
(and if we had a more massive Sun, everything would be sped up)
If you look at a distant galaxy, the stuff on the outer edges is moving too fast for the amount of visible matter.
So either theory is incomplete or there is invisible matter.
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Mindcrime you misinterpreted my explanation. Allow me to rephrase: When comparing the redshift of supernovae, one much farther away then the other we can notice two things. The first thing is that the redshift from the farthest nova has a redder light. The other thing is the the closer nova has undergone more redshift in proportion to it's distance as compared to the otherone. What we can infer from this is that the universe is expanding faster then it was long ago.
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It's true that a lot of these ideas originate from attempts to account for inconsistencies between theory and observation (dark matter), or attempts at mathematical reconciliation of incompatible theories (string theory). However, the fact that many of these ideas seem bizarre and relatively incomprehensible shouldn't really bother you. For starters, you need to consider the fact that extant theories which have been incredibly successful seem really weird when we try to conceptualize them. Quantum mechanics and general relativity at their core result in some extremely weird ideas (the particle is everywhere at once given certain probability boundaries, until you see it - then it's only in one place!; space and time are a continuum, and they are curved? what does that even mean).
Quantum mechanics and general relativity can only be conceptualized by distant analogy, and the physical realities they describe have no meaningful relation to our everyday experience of the world. What is important about those theories is not that they tell us how to look at the world, but rather because they are scientifically useful. The lines, of course, get blurred when these ideas are represented on tv-shows. The general viewer doesn't want to hear "scientists have foundl mathematical reconciliation between special relativity and newtonian gravity to be useful in more accurately describing the motions of large bodies", they want to hear "scientists have found that space and time are one, and you can travel back in time...maybe".
Essentially what I mean to say is that nothing in science is really true, it is only ever useful. Further, if current speculations and areas of theoretical research bother you, then so too should well established sciences (because they are just as weird).
Gyth: Have you read the book "Faster than the Speed of Light"? It talks about how a variable speed of light might provide an alternative to inflation (although it is talking about variation over time, not variation in different regions). It might interest you (it is a bit light on the science though...)
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On June 28 2010 14:02 gyth wrote:Show nested quote +Dark matter = something that we can measure the gravitational effects of but we cannot see As a more concrete example, think of the solar system. The planets on the farthest reaches travel at a slower rate than the ones near the Sun. (and if we had a more massive Sun, everything would be sped up) If you look at a distant galaxy, the stuff on the outer edges is moving too fast for the amount of visible matter. So either theory is incomplete or there is invisible matter.
What theory is incomplete? I dont get what youre geting at
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On June 28 2010 14:02 gyth wrote:Show nested quote +Dark matter = something that we can measure the gravitational effects of but we cannot see As a more concrete example, think of the solar system. The planets on the farthest reaches travel at a slower rate than the ones near the Sun. (and if we had a more massive Sun, everything would be sped up) If you look at a distant galaxy, the stuff on the outer edges is moving too fast for the amount of visible matter. So either theory is incomplete or there is invisible matter.
Huh? The planets further from the sun travel at a slower rate because they have further to go around the sun then the ones closer, not because of dark matter. Also the suns gravitational pull on those planets is less... g = GmM/r^2
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Most of the local stuff around Earth works fine without Dark Matter and Dark energy as far as I know. It's just the Universe as a whole that needs the two to work in our current physics model.
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On June 28 2010 14:03 Sparkyrabbit wrote:
Mindcrime you misinterpreted my explanation. Allow me to rephrase: When comparing the redshift of supernovae, one much farther away then the other we can notice two things. The first thing is that the redshift from the farthest nova has a redder light. The other thing is the the closer nova has undergone more redshift in proportion to it's distance as compared to the otherone. What we can infer from this is that the universe is expanding faster then it was long ago.
You're contradicting Hubble's Law. What is observed is that there is a linear relationship between redshift and distance.
This is why we think the universe is expanding at an accelerating rate.
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Huh? The planets further from the sun travel at a slower rate because they have further to go around the sun then the ones closer, not because of dark matter. Also the suns gravitational pull on those planets is less... g = GmM/r^2
Yes, and the stars traveling around galaxies can be observed to NOT follow the same relationships.
You're contradicting Hubble's Law. What is observed is that there is a linear relationship between redshift and distance.
The theory of dark energy came about because observation diverges from hubble's law.
P.S. The link contradicts hubble's law too.
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Dark Energy and Dark matter Particles have NOT been found yet. They're numerous experiments today to try and detect such particles (through gravitational waves though to be produced from black holes) Off the top of my head the current Experiments include the Large Hadron Collider (LHC) which is trying to produce said particles artificially for a fraction of a microsecond. They're also satelites in space which try to detect gravitons and gravitational waves as i Said earlier, however we still have no direct hard evidence for the existence of Dark Matter. (sorry had to bring that up after i skimmed some posts saying we had found particles or that Dark matter HAS to exist, its still just theoretical.
For my second part, im going to drop a twist on the big bang theory that i absolutely love. The Theory states that our universe could have been born in a black hole. Link to the story Here
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On June 28 2010 14:31 gyth wrote:Show nested quote +You're contradicting Hubble's Law. What is observed is that there is a linear relationship between redshift and distance. The theory of dark energy came about because observation diverges from hubble's law. P.S. The link contradicts hubble's law too.
....no
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Aotearoa39261 Posts
On June 28 2010 13:52 gyth wrote:I think you guys are being a little cavalier. An apple falling from a tree is an observation. But the reason is not so clear. Is it because all massive objects attract each other, or is it because massive objects distort space-time? (or is it just seeking its natural place?) Dark matter/energy make an assumption about what would be needed in order for the observation to fit current theory. But it could be that current theory just needs an overhaul. P.S. And observation based on doppler shifting would get a little dicey if assumptions, like the speed of light being constant, aren't right. To be perfectly honest, Dark Enery or Dark Matter doesn't "have" to exist. But the alternatives are really quite silly. The only other reasonable explanation is that Newton's law of gravitation behaves differently macroscopically. This really doesn't have much traction though, because at the moment there is no indication of the law breaking down at all so.... yea... Dark matter/energy is the most logical explanation for what we observe at the moment.
iirc, they ran a computer simulation of the galaxy being "born" from the big bang with the appropriate quantities of matter and dark matter and whatnot and the result was surprisingly accurate.
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I agree with Plexa for the most bit. Some of you are saying "dark energy HAS to exist" or "dark matter CANT exist" but the truth is, we don't know. We do know its the best theory we have right now. I read a few articles about how we "filled in" our lack of understanding with supernatural forces to explain why our theories don't make sense. It's akin to us inventing the mystical aether mentioned in the OP, but what scientists failed to realize was that their theories just didn't work, and a new theory was invented without use of the aether.
Note: Dark matter probably DOES exist, plenty of indirect evidence such as gravitational lensing. Dark energy..... ehh...... perhaps not.
There were a few articles on Science daily about how the cosmic microwave background radiation might be distorted, the distorition affecting the evidence for dark energy/matter. I'll have to check up on that.
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United States10328 Posts
On June 28 2010 14:31 gyth wrote:Show nested quote +Huh? The planets further from the sun travel at a slower rate because they have further to go around the sun then the ones closer, not because of dark matter. Also the suns gravitational pull on those planets is less... g = GmM/r^2 Yes, and the stars traveling around galaxies can be observed to NOT follow the same relationships.
For example, take the milky way galaxy. If there ere no dark matter and our existing theory of galactic formation (spinning glob flattens) holds, then the galaxy's rotation curve should look a certain way. Specifically, beyond the edge of the visible galaxy, objects' angular momentum should decrease... But that's not what's observed (observations indicate there's more mass inside those objects' orbit than can be seen, and we infer that mass to come from dark matter.
Show nested quote +You're contradicting Hubble's Law. What is observed is that there is a linear relationship between redshift and distance. The theory of dark energy came about because observation diverges from hubble's law. P.S. The link contradicts hubble's law too.
Hubble's law isn't contradicted; it holds at any instant in time (or so we believe). What's happening is Hubble's constant is changing.
See http://en.m.wikipedia.org/wiki/Hubble's_law, the graph on the "fate of the universe."
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as pandain said, dark matter probably does exist, just cuz of stars forming where nothing was before. could b black holes, but gravitation is not big enough for THAT. so yea, dark matter probably does exist. dark energy? idk.
btw: its just called "dark" cuz we cant observe it directly, in opposition to the rest of the universe. and, for the sake of completing the statement, most of the universe has to consist of "dark whatever". estimates are like: 74% dark energy, 22% dark matter and like 4% of visible matter. if the estimates are that high for things we cant observe, something has to be up and coming in the next few years. maybe LHC will shed some light on all that "dark" matters 
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The only other reasonable explanation is that Newton's law of gravitation behaves differently macroscopically. This really doesn't have much traction though, because at the moment there is no indication of the law breaking down at all so...
Newton's law of universal gravitation did break down. (general relativity)
Mindcrime
You're contradicting Hubble's Law. What is observed is that there is a linear relationship between redshift and distance. ]343[
Hubble's law isn't contradicted; it holds at any instant in time (or so we believe). What's happening is Hubble's constant is changing.
I was arguing over the linearity of the relationship.
My understanding is that we don't observe a linear relationship and that dark energy is the hypothetical reason for the change in slope.
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EPT
