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# Gravity is real you dumb fuckers

## Posts

• Registered User regular
Apothe0sis wrote: »
Al_wat wrote: »
Apothe0sis wrote: »
Al_wat wrote: »
The whole deal of the Big Bang with the soup of all the energy of the universe and the eventual coalescence of matter makes sense to me.

My question is... what mechanic or model is there to explain the massive expansion of space time?

Dark Energy and its repulsive force.

In what manner does this actually act on space time?

I understand this might be too complicated to answer in this thread.

I have hereby exhausted my knowledge of dark energy.

:lol:

I'm clearly not some professional physicist or anything (would I be asking dumb ass questions if I was?).

I just have a hard time picturing how matter or energy, you know, stuff, acts on Space time. Like I have trouble picturing Space-time as "stuff".

Not trying to say "I dont see how it is possible, therefore it isn't". I'm saying I am too stupid to picture it in my head.

• Registered User regular
Balloon analogy time:

Spacetime is like the surface of a balloon, in the sense that as you put air in it gets larger and larger and larger.

AFAIK stars can be considered to be dots drawn onto the surface of the balloon - as it expands they expand, naturally, but gravity holds them together tighter (locally) then the expansion of spacetime pulls them apart and so the distances between them increase.

My personal favorite end of the universe theory is that a repulsive force in the universe is increasing and eventually forces all matter apart at the subatomic level. Humankind dies screaming at t minus 5 minutes when it overcomes the elasticity of our intracellular matrix.

Dis' wrote: »
Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
• __BANNED USERS
AFAIK stars can be considered to be dots drawn onto the surface of the balloon - as it expands they expand, naturally, but gravity holds them together tighter (locally) then the expansion of spacetime pulls them apart and so the distances between them increase.

Yearghh my brain

• Registered User regular
My personal favorite end of the universe theory is that a repulsive force in the universe is increasing and eventually forces all matter apart at the subatomic level. Humankind dies screaming at t minus 5 minutes when it overcomes the elasticity of our intracellular matrix.

That is absolutely terrifying.

The list never changes: http://www.infinitebacklog.com
• Dublin, CARegistered User regular
big rip. or whatever. even heard of a cyclic version, because it is accelerating at some weird rate and eventually the math eventually brakes in a way very similar to how it breaks at the beginning. or some shit. Hell it beats a cold dead wimper.

it's sometime after our sun has burned out and turned into a giant diamond. not very pressing

RedX is taking a stab a moving out west, and will be near San Francisco from May 14 till June 29.
• Registered User, ClubPA regular
Apothe0sis wrote: »
A clue: Physics and science are not pure speculation.

An addendum: Not all "possibilities" are equal.

Well, relative to the discussion of gravity, they are. When you don't have verifiable proof what the fuck gravity is other than a "force", you would have to speculate as to what causes that force, correct? Maybe conjecture is a better way to describe it.

But it's not "a force". We know it's the curvature of spacetime as described by relativity. The question is what the curvature of spacetime is relative to the quantum mechanical model of the universe, summed up in many ways as "why is gravity so piss-weak to start with?"

Oh ho, but we don't know it's the curvature of space-time; in fact, we know that it is NOT the curvature of space-time, or at least not solely the curvature of space-time. Keep in mind if that it were absolutely true that it was the curvature of space-time, then that model would work perfectly with quantum mechanics, which it most certainly does not. The curved space-time model presents a very accurate model of macroscale gravitational effects, but it cannot be the whole story and it may in fact just be a model that happens to work out and the underlying mechanics behave like curved space-time but are in fact not curved space-time at all.

Hence my "as described by relativity". Relativity describes a very specific, continuous model of spacetime and over macroscopic scales perturbations of that are gravity in the sense that the calculations are pretty damn accurate when we use it.

Right, but the model of relativity is most certainly not complete, so we know that gravity isn't purely the curvature of space-time. You can't say "Well, we know that gravity is the curvature of space-time for these specific set of circumstances, but not for others." Gravity doesn't change it's very nature depending on what scale you look at it. There has to be one ultimate theory of gravity that applies equally well to all situations. All we can say is that for a specific set of circumstances, the model of curved space-time works rather well to describe gravity.

• Registered User regular
Apothe0sis wrote: »
There has to be one ultimate theory of gravity that applies equally well to all situations.

this is presumptuous because we love symmetry and elegance in science and math...but we keep on truckin

• Registered User, ClubPA regular
musanman wrote: »
Apothe0sis wrote: »
There has to be one ultimate theory of gravity that applies equally well to all situations.

this is presumptuous because we love symmetry and elegance in science and math...but we keep on truckin

Well, it doesn't make sense that for macroscale circumstances that gravity is actually space-time curvature, but once you get down to a small enough scale, it suddenly starts to be carried by little particles.

• Registered User regular
musanman wrote: »
Apothe0sis wrote: »
There has to be one ultimate theory of gravity that applies equally well to all situations.

this is presumptuous because we love symmetry and elegance in science and math...but we keep on truckin

Well, it doesn't make sense that for macroscale circumstances that gravity is actually space-time curvature, but once you get down to a small enough scale, it suddenly starts to be carried by little particles.

it doesn't start to be carried by little particles, it's just that all the particles are of small enough mass that it can noticeably effect them. They're just like little solar systems

• Registered User
I like how people are chiming in to say, "Yes, gravity is real". In fact, there are so many of you doing it, that I can't be bothered to name you!

I appreciate you guys, I don't know how anyone could've argued for the existence of gravity without you. They are not qualified to drop a pencil from their hand and see if it makes contact with carpet.

They need you guys.

"Bam!" - Emeril Legasse
• Registered User regular
somewhat related, entertaining post I found on slashdot
no. gravity is a secular, materialistic theory perpetrated by atheists and family-destroying liberals who deny the inspired truth of the bible. the correct interpretation, of course, is "intelligent falling".

• Per Aspera Ad Inferi Super Moderator, Moderator mod
I made the intelligent falling joke on page one, damnit!

• Registered User regular
musanman wrote: »
Apothe0sis wrote: »
There has to be one ultimate theory of gravity that applies equally well to all situations.

this is presumptuous because we love symmetry and elegance in science and math...but we keep on truckin

I don't remember saying that. Where did I say that?

You keep on truckin' you big rig driver, you.

What I see sees me.
SODOMISE INTOLERANCE
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• Registered User regular
Apothe0sis wrote: »
Al_wat wrote: »
The whole deal of the Big Bang with the soup of all the energy of the universe and the eventual coalescence of matter makes sense to me.

My question is... what mechanic or model is there to explain the massive expansion of space time?

Dark Energy and its repulsive force.

This. This here. This causes me great irritation and discontent.

Gravity works, right, except that then we discover that, err, some stuff is moving about four hundred times faster than it should be. We don't know why. Our math cannot explain it. We therefore decide that there must be four hundred times more shit in the void than we knew about, only we can't see it because it doesn't interact with anything in any way other than gravity.

I look at this, and I see a bunch of scientists going, "Why in the fuck doesn't our math work?! You know what? Fuck it. I am straight-up not smart enough for this shit and thinking about it is giving me a grade-seven Ice Cream Headache. Throw in a constant and call it dark matter."

I mean at that point you think it'd be pretty clear that the model's just fundamentally broken in backasswards fundamental ways we're not smart enough to understand yet - which is already a given due to the QM/Relativity weirdness - but we prop it up with (very very very large) space unicorn turds instead. Like, man up, dudes.

• Registered User regular
Apothe0sis wrote: »
Al_wat wrote: »
The whole deal of the Big Bang with the soup of all the energy of the universe and the eventual coalescence of matter makes sense to me.

My question is... what mechanic or model is there to explain the massive expansion of space time?

Dark Energy and its repulsive force.

This. This here. This causes me great irritation and discontent.

Gravity works, right, except that then we discover that, err, some stuff is moving about four hundred times faster than it should be. We don't know why. Our math cannot explain it. We therefore decide that there must be four hundred times more shit in the void than we knew about, only we can't see it because it doesn't interact with anything in any way other than gravity.

I look at this, and I see a bunch of scientists going, "Why in the fuck doesn't our math work?! You know what? Fuck it. I am straight-up not smart enough for this shit and thinking about it is giving me a grade-seven Ice Cream Headache. Throw in a constant and call it dark matter."

I mean at that point you think it'd be pretty clear that the model's just fundamentally broken in backasswards fundamental ways we're not smart enough to understand yet - which is already a given due to the QM/Relativity weirdness - but we prop it up with (very very very large) space unicorn turds instead. Like, man up, dudes.
I hear this argument a ridiculous number of times from people outside scientific disciplines and all I can think is "ok, what's your answer?"

Scientists work off evidence. If the evidence shows that you're model which works well in most respects is broken in some way, then you start postulating some solutions and go looking for evidence that the postulates are correct.

The thing is, just because we understand the basic theory of some process does not mean that we can automatically interpret every possible permutation of the interaction of various objects within that theory. For example, we understand the basic energy states of the atom extremely well and the mechanics of simple chemical bonding, but moving even vaguely beyond diatomic systems and very quickly we only have a number of approximate techniques for determining bond strengths and electron densities.

Do these results mean that our theory of atomic chemical bonding is wrong, or does it simply mean that we don't have the mathematical tools to apply the theory to model more complicated systems?

Dis' wrote: »
Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
• Registered User regular
Plus, dark matter ande dark energy are totally different things.

What I see sees me.
SODOMISE INTOLERANCE
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• Registered User, ClubPA regular
I thought we'd spotted dark matter? Wasn't there that one fancy image a few months back?

• Registered User regular
The Cat wrote: »
I thought we'd spotted dark matter? Wasn't there that one fancy image a few months back?

I thought it to be the case as well - we'd seen the gravitational lensing from it IIRC.

What I see sees me.
SODOMISE INTOLERANCE
Tide goes in. Tide goes out.
• Registered User regular
The Cat wrote: »
I thought we'd spotted dark matter? Wasn't there that one fancy image a few months back?

I love that image, but the modified newtonian dynamics people came out like 3 days later saying they could totally explain it.

Dis' wrote: »
Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
• Registered User regular
I could be totally wrong (too much alcohol last night... faulty brain and memory) , but I thought that dark matter image was just an overlay of where dark matter is supposed to be based on gravitational effects observed on nearby matter.

Meaning they didn't detect shit, really.

• Registered User regular
Gravity is real. I don't think dark matter is real, however. Everyone assumes that gravity can only exist where something has mass, which is silly. We don't know the first thing about how gravity actually works, so why can't a pocket of gravitation exist without being attached to some massive object?

Someone will say "we have only observed gravity existing where there is mass," but that isn't true. The entire reason people insist on some kind of "dark matter" is because we've observed gravity where there is no mass attached to it.

EDIT: Al_wat is 100% correct. They didn't detect shit. They only observed gravitational lensing, with no massive object appearing responsible for it.

3DS Friend Code: 0817-5033-8184 // Nintendo Network ID: AbsoluteZero
• Registered User regular
Apothe0sis wrote: »
Al_wat wrote: »
The whole deal of the Big Bang with the soup of all the energy of the universe and the eventual coalescence of matter makes sense to me.

My question is... what mechanic or model is there to explain the massive expansion of space time?

Dark Energy and its repulsive force.

This. This here. This causes me great irritation and discontent.

Gravity works, right, except that then we discover that, err, some stuff is moving about four hundred times faster than it should be. We don't know why. Our math cannot explain it. We therefore decide that there must be four hundred times more shit in the void than we knew about, only we can't see it because it doesn't interact with anything in any way other than gravity.

I look at this, and I see a bunch of scientists going, "Why in the fuck doesn't our math work?! You know what? Fuck it. I am straight-up not smart enough for this shit and thinking about it is giving me a grade-seven Ice Cream Headache. Throw in a constant and call it dark matter."

I mean at that point you think it'd be pretty clear that the model's just fundamentally broken in backasswards fundamental ways we're not smart enough to understand yet - which is already a given due to the QM/Relativity weirdness - but we prop it up with (very very very large) space unicorn turds instead. Like, man up, dudes.
I hear this argument a ridiculous number of times from people outside scientific disciplines and all I can think is "ok, what's your answer?"

Scientists work off evidence. If the evidence shows that you're model which works well in most respects is broken in some way, then you start postulating some solutions and go looking for evidence that the postulates are correct.

The thing is, just because we understand the basic theory of some process does not mean that we can automatically interpret every possible permutation of the interaction of various objects within that theory. For example, we understand the basic energy states of the atom extremely well and the mechanics of simple chemical bonding, but moving even vaguely beyond diatomic systems and very quickly we only have a number of approximate techniques for determining bond strengths and electron densities.

Do these results mean that our theory of atomic chemical bonding is wrong, or does it simply mean that we don't have the mathematical tools to apply the theory to model more complicated systems?

It seems more like they have been looking for ways for their model to be correct, rather than looking for a model that is correct. Dark Matter/Energy may very well be this century's "The Earth is flat" or "The Sun revolves around the Earth."

3DS Friend Code: 0817-5033-8184 // Nintendo Network ID: AbsoluteZero
• Registered User regular
Apothe0sis wrote: »
Al_wat wrote: »
The whole deal of the Big Bang with the soup of all the energy of the universe and the eventual coalescence of matter makes sense to me.

My question is... what mechanic or model is there to explain the massive expansion of space time?

Dark Energy and its repulsive force.

This. This here. This causes me great irritation and discontent.

Gravity works, right, except that then we discover that, err, some stuff is moving about four hundred times faster than it should be. We don't know why. Our math cannot explain it. We therefore decide that there must be four hundred times more shit in the void than we knew about, only we can't see it because it doesn't interact with anything in any way other than gravity.

I look at this, and I see a bunch of scientists going, "Why in the fuck doesn't our math work?! You know what? Fuck it. I am straight-up not smart enough for this shit and thinking about it is giving me a grade-seven Ice Cream Headache. Throw in a constant and call it dark matter."

I mean at that point you think it'd be pretty clear that the model's just fundamentally broken in backasswards fundamental ways we're not smart enough to understand yet - which is already a given due to the QM/Relativity weirdness - but we prop it up with (very very very large) space unicorn turds instead. Like, man up, dudes.
I hear this argument a ridiculous number of times from people outside scientific disciplines and all I can think is "ok, what's your answer?"

Scientists work off evidence. If the evidence shows that you're model which works well in most respects is broken in some way, then you start postulating some solutions and go looking for evidence that the postulates are correct.

The thing is, just because we understand the basic theory of some process does not mean that we can automatically interpret every possible permutation of the interaction of various objects within that theory. For example, we understand the basic energy states of the atom extremely well and the mechanics of simple chemical bonding, but moving even vaguely beyond diatomic systems and very quickly we only have a number of approximate techniques for determining bond strengths and electron densities.

Do these results mean that our theory of atomic chemical bonding is wrong, or does it simply mean that we don't have the mathematical tools to apply the theory to model more complicated systems?

It seems more like they have been looking for ways for their model to be correct, rather than looking for a model that is correct. Dark Matter/Energy may very well be this century's "The Earth is flat" or "The Sun revolves around the Earth."

Didn't we actually find evidence of dark matter a little while ago? Something about two gaseous masses colliding, the gaseous particles slowing each other down, but the gravetic field continuing to shift as if most of the mass hadn't been slowed?

• Registered User regular
"The earth is flat because that's how we've always thought of it and I'll murder you if you say any different" is a lot different from "our theory works pretty well but it's missing something here and this is what we propose to fill in that gap for now."

Inquisitor wrote: »
• Registered User regular
Yeah, this is just like the time from the 1886 - 1930 that astronomers tried to fix their theory of gravity and the like when they discovered that Uranus' orbit was not what was predicted by the model - it just didn't match the calculations. Instead of looking for the correct model they tried to find ways for their model to be correct.

Bastards. It's almost like they don't know how to do science.

What I see sees me.
SODOMISE INTOLERANCE
Tide goes in. Tide goes out.
• Registered User regular
jothki wrote: »
Apothe0sis wrote: »
Al_wat wrote: »
The whole deal of the Big Bang with the soup of all the energy of the universe and the eventual coalescence of matter makes sense to me.

My question is... what mechanic or model is there to explain the massive expansion of space time?

Dark Energy and its repulsive force.

This. This here. This causes me great irritation and discontent.

Gravity works, right, except that then we discover that, err, some stuff is moving about four hundred times faster than it should be. We don't know why. Our math cannot explain it. We therefore decide that there must be four hundred times more shit in the void than we knew about, only we can't see it because it doesn't interact with anything in any way other than gravity.

I look at this, and I see a bunch of scientists going, "Why in the fuck doesn't our math work?! You know what? Fuck it. I am straight-up not smart enough for this shit and thinking about it is giving me a grade-seven Ice Cream Headache. Throw in a constant and call it dark matter."

I mean at that point you think it'd be pretty clear that the model's just fundamentally broken in backasswards fundamental ways we're not smart enough to understand yet - which is already a given due to the QM/Relativity weirdness - but we prop it up with (very very very large) space unicorn turds instead. Like, man up, dudes.
I hear this argument a ridiculous number of times from people outside scientific disciplines and all I can think is "ok, what's your answer?"

Scientists work off evidence. If the evidence shows that you're model which works well in most respects is broken in some way, then you start postulating some solutions and go looking for evidence that the postulates are correct.

The thing is, just because we understand the basic theory of some process does not mean that we can automatically interpret every possible permutation of the interaction of various objects within that theory. For example, we understand the basic energy states of the atom extremely well and the mechanics of simple chemical bonding, but moving even vaguely beyond diatomic systems and very quickly we only have a number of approximate techniques for determining bond strengths and electron densities.

Do these results mean that our theory of atomic chemical bonding is wrong, or does it simply mean that we don't have the mathematical tools to apply the theory to model more complicated systems?

It seems more like they have been looking for ways for their model to be correct, rather than looking for a model that is correct. Dark Matter/Energy may very well be this century's "The Earth is flat" or "The Sun revolves around the Earth."

Didn't we actually find evidence of dark matter a little while ago? Something about two gaseous masses colliding, the gaseous particles slowing each other down, but the gravetic field continuing to shift as if most of the mass hadn't been slowed?

D:

Top of this page dude. They didn't detect shit. They only observed gravitational lensing, with no massive object appearing responsible for it. There has yet to be any direct observation of dark matter. All they detected was gravity, and they can't explain why it is there, so they are saying "dark matter must be doing it!"

3DS Friend Code: 0817-5033-8184 // Nintendo Network ID: AbsoluteZero
• Registered User regular
Apothe0sis wrote: »
Yeah, this is just like the time from the 1886 - 1930 that astronomers tried to fix their theory of gravity and the like when they discovered that Uranus' orbit was not what was predicted by the model - it just didn't match the calculations. Instead of looking for the correct model they tried to find ways for their model to be correct.

Bastards. It's almost like they don't know how to do science.

Just seems a little stupid to me to close out the possibility that x model is fundamentally broken. "There MUST be dark matter because otherwise our model doesn't work!" They must realize that the universe does not operate according to their model.

3DS Friend Code: 0817-5033-8184 // Nintendo Network ID: AbsoluteZero
• Registered User
Gravity is real. I don't think dark matter is real, however. Everyone assumes that gravity can only exist where something has mass, which is silly. We don't know the first thing about how gravity actually works, so why can't a pocket of gravitation exist without being attached to some massive object?

Someone will say "we have only observed gravity existing where there is mass," but that isn't true. The entire reason people insist on some kind of "dark matter" is because we've observed gravity where there is no mass attached to it.

EDIT: Al_wat is 100% correct. They didn't detect shit. They only observed gravitational lensing, with no massive object appearing responsible for it.

That's all it is, though. "This galaxy acts like it has way more mass than it actually does. What the fuck?" "Okay, no, calm down. What if we assume that it's full of invisible matter?" "Huh, that seems to work. Weird."

• Registered User regular
Apothe0sis wrote: »
Yeah, this is just like the time from the 1886 - 1930 that astronomers tried to fix their theory of gravity and the like when they discovered that Uranus' orbit was not what was predicted by the model - it just didn't match the calculations. Instead of looking for the correct model they tried to find ways for their model to be correct.

Bastards. It's almost like they don't know how to do science.

Just seems a little stupid to me to close out the possibility that x model is fundamentally broken. "There MUST be dark matter because otherwise our model doesn't work!" They must realize that the universe does not operate according to their model.

Congratulations, you fail at the Philosophy of Science. Please collect your coat on the way out.

What I see sees me.
SODOMISE INTOLERANCE
Tide goes in. Tide goes out.
• Registered User regular
Apothe0sis wrote: »
Apothe0sis wrote: »
Yeah, this is just like the time from the 1886 - 1930 that astronomers tried to fix their theory of gravity and the like when they discovered that Uranus' orbit was not what was predicted by the model - it just didn't match the calculations. Instead of looking for the correct model they tried to find ways for their model to be correct.

Bastards. It's almost like they don't know how to do science.

Just seems a little stupid to me to close out the possibility that x model is fundamentally broken. "There MUST be dark matter because otherwise our model doesn't work!" They must realize that the universe does not operate according to their model.

Congratulations, you fail at the Philosophy of Science. Please collect your coat on the way out.

Right.

3DS Friend Code: 0817-5033-8184 // Nintendo Network ID: AbsoluteZero
On the other hand, the orbit of mercury was only explained by the theory of relativity (which went contested for a while due to the predictions it made being hard to verify). The bullet cluster data is pretty compelling as evidence for dark matter (Basicly, 2 clusters of galaxies collided, and as a result, the matter split, which was shown by X-ray / visible light / gravitational lensing). Calculations show that the mass that went straight trough is far, far more massive then what collided. Where you expect the mass, nothing can be seen). This tends to agree with dark matter being only gravitational matter, not affected by electromagnetic forces.

This did not alter the theory of dark matter in any way (except lower the constraints about how much dark matter interacts in a non-gravitational way). It's an observed effect, pretty much perfectly confirming what theory predicted.

There are competing models out there (Modified Newtonian Dynamics) that predict much the same results, but the majority of scientists do not back this. I'm not an astronomer, so I can't really judge which one is right. MOND is rewriting the law of gravity to allow for different gravitional pull at very low strengths, and keeps on getting more complex as new observations are made which it simpler forms cannot explain. (And this creates compatibility problems with Relativity, which is very elegant, derived instead of constructed to fit data) Dark Matter keeps getting "weirder" as more and more possible types of matter (baryonic matter, neutrino's) are excluded from the possibilities of what this matter can be. The main options are now particles predicted by super symmetry, which also appear in many string theories.

There are experiments on the way in the LHC which hopefully will shine some light on this, as well as experiments to find gravitional waves (which are predicted by relativity), and dark matter interacting with normal matter (very weakly, as predicted by some of the dark matter theories).

Dark Energy is a different thing, as it is mostly a factor to explain the fact that the universe is expanding faster then it should, and that the expansion appears to be accelerating. Interesting is that this effect can be included in theory by giving totally empty space an inherent energy value. Dark matter and dark energy share a similar name because of the fact that it appears to be unobservabe.

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Top of this page dude. They didn't detect shit. They only observed gravitational lensing, with no massive object appearing responsible for it. There has yet to be any direct observation of dark matter. All they detected was gravity, and they can't explain why it is there, so they are saying "dark matter must be doing it!"

What do you mean by "direct observation"? Dark matter by definition can only be detected due to its gravitational effect. If we could see it then it wouldn't be dark matter.

• Registered User regular
If gravity roams the universe freely then the simple question is "why?" and ho-hum maybe it's attached to a type of gravity only matter? And maybe this matter doesn't interact with anything else, so it would be "dark" and invisible compared to ordinary matter.

Dis' wrote: »
Cancer is when cells stop letting the body mooch off their hard work - clearly a community of like-minded cells should isolate themselves and do the best job each can do, even if the rest of the body collapses!
• Registered User
Apothe0sis wrote: »
Yeah, this is just like the time from the 1886 - 1930 that astronomers tried to fix their theory of gravity and the like when they discovered that Uranus' orbit was not what was predicted by the model - it just didn't match the calculations. Instead of looking for the correct model they tried to find ways for their model to be correct.

Bastards. It's almost like they don't know how to do science.

Just seems a little stupid to me to close out the possibility that x model is fundamentally broken. "There MUST be dark matter because otherwise our model doesn't work!" They must realize that the universe does not operate according to their model.

Generally, if a model doesn't match the observable data, you try to modify it so that it does. This is the sensible thing to do.

• Registered User, ClubPA regular
Al_wat wrote: »
I could be totally wrong (too much alcohol last night... faulty brain and memory) , but I thought that dark matter image was just an overlay of where dark matter is supposed to be based on gravitational effects observed on nearby matter.

Meaning they didn't detect shit, really.

*facepalm*

No, we did detect it. See, matter in this universe interacts with other things via the four fundamental forces. Two of those forces (electromagnetism and gravity) are the two forces which allow us to see things far away. A lot of the time, we observe things by observing the electromagnetic energy they give off which comes to us as... light! However, we also observe things by observing the gravitational energy they give off. We've observed dark matter because we found areas that there should be massive heaps of matter and there isn't anything visible via electromagnetic energy. Tada!

• Registered User, ClubPA regular
Gravity is real. I don't think dark matter is real, however. Everyone assumes that gravity can only exist where something has mass, which is silly. We don't know the first thing about how gravity actually works, so why can't a pocket of gravitation exist without being attached to some massive object?

Someone will say "we have only observed gravity existing where there is mass," but that isn't true. The entire reason people insist on some kind of "dark matter" is because we've observed gravity where there is no mass attached to it.

Well, we know dark matter is real. There's a little particle that you probably heard of but didn't realise is dark matter: the neutrino. We have detected them in experiments based in laboratories, we've managed to get quite a bit of information from them, and they are predicted by the standard model.

So, we know there's at least one particle that has gravitational influence but almost no electromagnetic influence. So, we either accept that our models of gravity are completely wrong and there is something that goes against everything we've observed, or we take this little particle we have observed, hypothesize that there are particles like it that have gravitational influence but not electromagnetic influence, and run with it. The latter just makes more sense.

• Registered User regular
I have a question. Is there a possibility of the universe collapsing on itself? Have we thought anything about that? Einstein wasn't even sure whether the universe was infinite IIRC.

• Registered User regular
ArrBeeBee wrote: »
Apothe0sis wrote: »
Yeah, this is just like the time from the 1886 - 1930 that astronomers tried to fix their theory of gravity and the like when they discovered that Uranus' orbit was not what was predicted by the model - it just didn't match the calculations. Instead of looking for the correct model they tried to find ways for their model to be correct.

Bastards. It's almost like they don't know how to do science.

Just seems a little stupid to me to close out the possibility that x model is fundamentally broken. "There MUST be dark matter because otherwise our model doesn't work!" They must realize that the universe does not operate according to their model.

Generally, if a model doesn't match the observable data, you try to modify it so that it does. This is the sensible thing to do.

you can apply fractions and a natural log to any set of completely random data and turn that bad boy into a straight line and then write a thesis proving ridiculous shit like cloud altitude and its effects on your headshot percentages in team fortress

• Registered User regular
Gravity is real. I don't think dark matter is real, however. Everyone assumes that gravity can only exist where something has mass, which is silly. We don't know the first thing about how gravity actually works, so why can't a pocket of gravitation exist without being attached to some massive object?

Someone will say "we have only observed gravity existing where there is mass," but that isn't true. The entire reason people insist on some kind of "dark matter" is because we've observed gravity where there is no mass attached to it.

EDIT: Al_wat is 100% correct. They didn't detect shit. They only observed gravitational lensing, with no massive object appearing responsible for it.

The difference betwen "A pocket of gravitation" and "Some massive object" is only semantics.

Unless you mean something with gravitation but no inertial mass, which would be rather impossible as with no inertial mass it would move towards the center of gravity of the universe at the speed of light, which would make it rather hard for it to be relatively uniformly distributed throughout the universe, indeed there would just be a big clump of them at the center of the universe and that would be that.

Edit: Or they would just merge with whatever massive object they came into close proximity with on the way there.

Edit 2 : I guess thinking about it a bit more that you could have a particle with no mass but energy which produced gravitation like a photon does, but that particle would still have momentum (fixed as a function of its energy) and would be always be traveling at the speed of light in any case.

So in total:

A massless, energyless particle expressing the property of gravitation would immediately travel at the speed of light in whatever direction the sum of the gravitational forces on it dictated, ending up generally in the middle of some massive object or at the center of gravity of some massive system.

A massless particle with energy and gravity would act like a photon, and behave as a photon does (and this is what a photon is, essentially, and existing models already incorporate this).

Neither possibility could adequately explain observations seen by dark matter.

• Registered User, ClubPA regular
No-Quarter wrote: »
I have a question. Is there a possibility of the universe collapsing on itself? Have we thought anything about that? Einstein wasn't even sure whether the universe was infinite IIRC.

The universe is finite without boundaries as far as we can tell. In other words, it's the surface of a sphere. Is it collapsing on itself? Well, the theory is that the end of the universe would either end in a heat death or by collapsing back on itself. If mass pressure is high enough that it eventually slows and then reverses the rate of expansion of the universe, then it collapses on itself. For a long time, it was assumed the latter would occur, but now evidence seems to be suggesting that the expansion of the universe is accelerating, which means it will not collapse on itself.