Welcome to the Shroomery Message Board! You are experiencing a small sample of what the site has to offer. Please login or register to post messages and view our exclusive members-only content. You'll gain access to additional forums, file attachments, board customizations, encrypted private messages, and much more!
|
 5HTSynaptrip
Dopamine Enthusiast
Registered: 09/14/08
Posts: 4,353
Loc: USA 
Last seen: 1 month, 3 days
|
 Gravity so weak....? 
#13249220 - 09/26/10 02:59 PM (2 years, 7 months ago) |
|
|
I know very little about physics. Just want to get that out of the way...
We all know that gravity is a weak force but it does bend space-time so are there are other forces that do the same thing? Is that exclusive to gravity (and of course mass)?
--------------------
Science is a way of thinking much more than it is a body of knowledge. - My hero, who will be forever remembered, Carl Sagan.
|
 enthiangenic
Registered: 02/14/10
Posts: 470
|
|
I wouldn't call gravity at all but there are 4 forces that govern the universe: Gravity, the Electromagnetic force, the Strong Nuclear force, and the Weak Nuclear force...these are the known forces
|
enthiangenic
Registered: 02/14/10
Posts: 470
|
|
this doesn't answer your question but each of the 4 forces interact on the universe and each other in different ways
|
DieCommie
El Guapo
Registered: 12/11/03
Posts: 25,374
Loc: Street of Dreams
|
|
I believe it is exclusive to gravity. Also note that energy in general bends space time, and mass is an example of that. A massless photon also bends space time.
|
johnm214
Registered: 05/31/07
Posts: 16,557
Loc: Americas
|
|
Quote:
5HTSynaptrip said:
I know very little about physics. Just want to get that out of the way...
We all know that gravity is a weak force but it does bend space-time so are there are other forces that do the same thing? Is that exclusive to gravity (and of course mass)?
A bit of a demurrer, but I'd say gravity is the bend in space time. That being said, it is less meaningful to ask if any other fundamental force does this as if they did that they would be gravity, not a fundamental force other than gravity.
I mean, if you have a shit ton of electromagnetic energy at a point, due to the equivalence principle I'd imagine that would have to warp space time as well, but then surely the warping is a gravitational effect rather than an electromagnetic effect, right?
That's at least what I thought of when reading your question- that it kinda doesn't make sense because its like asking if another force behaves as the strong force- if it did it would be the strong force- wouldn't it?
|
SuperD
Lophophiend
Registered: 10/05/03
Posts: 5,747
Loc: My stash box
|
Re: Gravity so weak....? [Re: johnm214]
#13249414 - 09/26/10 03:46 PM (2 years, 7 months ago) |
|
|
I'm still trying to grasp the whole concept of gravity, it's a tough one. How can something millions of miles away such as our Sun affect other planets around it without any visible attachment?
--------------------
  
Manoa said:
I need to stop spending all my money on plants and take up a cheaper hobby, like heroin.
|
DieCommie
El Guapo
Registered: 12/11/03
Posts: 25,374
Loc: Street of Dreams
|
Re: Gravity so weak....? [Re: SuperD]
#13249709 - 09/26/10 04:58 PM (2 years, 7 months ago) |
|
|
The best you can do probably, is embrace the metaphors from science documentaries.
From a general relativity perspective, mass and energy bend space time. This bent space time is not like the 'regular' (euclidean) space that we intuitively know. In this bent, non-euclidean space 'straight' lines (geodesics) can curve and connect back to themselves. (Consider drawing a straight line on a globe, it connects back to itself. A globe is an example of non-euclidean geometry) So the mass and energy of the sun bend space time around it and make it so straight lines are no longer straight. The earth then does what all mass does, it follows a straight line. Only now, the space time is bent so that it travels around in a circle. This is the basic working behind general relativity. Mass and energy bend space time. Mass and energy feel the effect of bent space time. Mass and energy each bend space time and feel the effect of it.
There is also a quantum mechanical perspective on gravity which is different and not well developed. In quantum mechanics all the forces are mediated by force carrying particles. How does one thing 'reach out' and apply a force to another thing? It sends a force carrying particle. So for the strong nuclear force there is a gluon, it carrys the force in a sense. For the weak nuclear force there are some bosons that do it. For the electromagnetic force, photons are the carrying particle. These three forces are very well explained in quantum mechanics and the usage of these force carrying particles has provided one of the most accurate scientific theories man has ever created. There has been alot of difficulty trying to get gravity to fit into this frame work though. The name of gravity's force carrying particle is the graviton, and as I mentioned its not very well developed and does not yet provide new accurate predictions.
|
and yet it moves
Freeform
Registered: 08/21/10
Posts: 297
Loc: poORtland by way of en ja...
Last seen: 23 days, 19 hours
|
Re: Gravity so weak....? [Re: SuperD]
#13249734 - 09/26/10 05:05 PM (2 years, 7 months ago) |
|
|
there's also the "quintessense" force, the so-called "dark energy" or "antigraviy," which is still a fairly speculative concept. but from what i've read, that's really only noticeable on really large (galactic) scales... i don't think that bends space-time so much as it is the latent energy of the vacuum.... i should warn you that i don't really know what i'm talking about seeing as i've never passed a physics course in my life, this is just what i've picked up from the universe of pop-science...
|
johnm214
Registered: 05/31/07
Posts: 16,557
Loc: Americas
|
Re: Gravity so weak....? [Re: SuperD]
#13250271 - 09/26/10 07:33 PM (2 years, 7 months ago) |
|
|
Quote:
SuperD said:
I'm still trying to grasp the whole concept of gravity, it's a tough one. How can something millions of miles away such as our Sun affect other planets around it without any visible attachment?
I would think of it not neccesarily effecting the planets (the sun affecting the earth) but rather defining the space in which the earth and sun are located. Makes a bit more sense in that framework.
From a conceptual point of view I've also been trying to understand gravity, and the usual metaphors leave a lot to be desired. I would think a good model is mass sucking in (accelerating) space at a rate proportional to the inverse sqaure of the distance from it. So far as I can tell, not very deeply, this vacuum cleaner sucking thing is accurate and something I can conceptualize.
i.e. the balls on the rubber sheet or fabric sheet making an indentation is all well and good, but it doesn't really explain why stationary masses start to move towards massive objects, why a stationary ball will fall to the earth, nor does it explain why a force is felt by something not falling, the ball laying on the ground.
Maybe that will help you out- I'd be interested to see if qubit can punch any hole's in that.
|
SuperD
Lophophiend
Registered: 10/05/03
Posts: 5,747
Loc: My stash box
|
Re: Gravity so weak....? [Re: johnm214]
#13250485 - 09/26/10 08:23 PM (2 years, 7 months ago) |
|
|
The way you worded it does make it a bit easier to digest.
--------------------
Manoa said:
I need to stop spending all my money on plants and take up a cheaper hobby, like heroin.
|
OddEye
Registered: 10/08/04
Posts: 440
Last seen: 2 days, 32 minutes
|
Re: Gravity so weak....? [Re: SuperD]
#13259275 - 09/28/10 03:41 PM (2 years, 7 months ago) |
|
|
The only thing I don't understand about this whole thing is why the fuck do planet don't crash into each other and orbit each other instead. I actually have a "good" understanding of the universe, but I still dunno that lol. Is it the electromagnetic field?(doesn't rly make sens since only earth has one)
--------------------
I'm at the highest peak, still glad the meak is understandin' me
Artillery, thoughts of killin' me is just a fantasy
The man in me is ready for war, like Holyfield-Tyson IV
|
johnm214
Registered: 05/31/07
Posts: 16,557
Loc: Americas
|
Re: Gravity so weak....? [Re: OddEye]
#13259342 - 09/28/10 03:53 PM (2 years, 7 months ago) |
|
|
Quote:
OddEye said:
The only thing I don't understand about this whole thing is why the fuck do planet don't crash into each other and orbit each other instead. I actually have a "good" understanding of the universe, but I still dunno that lol. Is it the electromagnetic field?(doesn't rly make sens since only earth has one)
They do crash into each other, you just aren't watching long enough : )
The orbiting is because the planets have momentum with respect to the star, and this must be conserved. If you imagine a planet strolling along that suddenly gets 'captured' by a star's gravitational field (so to speak), their original relative motion doesn't disapear. This is what results in the orbiting: the planet has angular momentum with respect to the star because it had velocity with respect to the star. This is pretty much the same as one of those coin-drop funnels that have the coin orbit the funnel's hole- it doesn't drop directly in the hole because of the angular momentum. As friction causes the momentum to decrease, the orbit does too, and eventually the coin falls in the hole and the planet into the star.
(think of the tangential velocity of the planet in an orbit, it is in a direction which would take it away from the star and this momentum is what keeps it from simply dropping like a stone from our outsider's perspective).
|
DieCommie
El Guapo
Registered: 12/11/03
Posts: 25,374
Loc: Street of Dreams
|
Re: Gravity so weak....? [Re: johnm214]
#13259504 - 09/28/10 04:21 PM (2 years, 7 months ago) |
|
|
Quote:
From a conceptual point of view I've also been trying to understand gravity, and the usual metaphors leave a lot to be desired. I would think a good model is mass sucking in (accelerating) space at a rate proportional to the inverse sqaure of the distance from it. So far as I can tell, not very deeply, this vacuum cleaner sucking thing is accurate and something I can conceptualize.
Your vacuum analogy is accurate in the same way that newtonian physics is accurate. You are getting around the difficulty of conceptualizing general relativity gravity by going back to newtonian gravity.
I know you dont mean sucking literally, but its interesting that you use such an idea. What is sucking? Its when you remove pressure at one spot and then the resulting imbalance causes a flow towards the new low pressure area. The low pressure area isnt pulling anything, its the high pressure area that is pushing. After newton came up with his theory, people tried to explain gravity by a very similar idea. The idea was that a sea of unseen particles are impacting the earth from all places. But the sun blocks those particles that would have been coming from the sun's direction. The result is a net push towards the sun. http://en.wikipedia.org/wiki/Le_Sage%27s_theory_of_gravitation
Of course, this is not the case. Newton's word on how gravity works, well it might be as good as you will ever get "Hitherto I have not been able to discover the cause of those properties of gravity from the phenomena, and I frame no hypothesis; for whatever is not deduced from the phenomena is to be called an hypothesis; and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy. "
Quote:
i.e. the balls on the rubber sheet or fabric sheet making an indentation is all well and good, but it doesn't really explain why stationary masses start to move towards massive objects, why a stationary ball will fall to the earth, nor does it explain why a force is felt by something not falling, the ball laying on the ground.
It does if you kind of massage the metaphor. Remember that the sheet originally has straight lines drawn on it. These lines in our euclidean geometry perspective represent what are called geodesics in general relativity (G.R.) geometry. If there is no mass or energy around, then these two perspectives agree. G.R.'s geometry looks like 'flat' euclidean geometry with no mass/energy around. Now if you put some mass on the eucledian sheet, it will bend. If you look at it from the top the lines that were straight are no longer straight. The same thing happens in G.R., the lines are not longer what we think of as straight. These lines represent how objects will move. In the pre mass/energy sheet, the lines were straight and the object would just move along them. If you were moving with the object, it would appear to be still and you would see a point not a line. Now that we have mass/energy the lines bend. In the eucledian sheet they curve a little around the mass/energy. In G.R. they bend towards the mass/energy. So now instead of an object going straight, it will bend a little towards the mass/energy. If the mass/energy is large enough, the geodesic will curve back on itself and form a closed loop. So a planet just moves along in a 'straight' line, like we expect. But it doesn't live in a euclidean space, it lives an a G.R. space where straight lines (geodesics) can curve back on themselves.
This wikipedia may help a little: http://en.wikipedia.org/wiki/Geodesic
So for your examples, a stationary mass is being held by something. Its on a geodesic, but that which holds it is pulling it out. Once you let go, it continues on its geodesic towards the mass/energy. If something is laying on the ground, its geodesic in part points towards the center of the earth, and in part points around the sun. The electric force of the atoms on the ground are pulling it out of its geodesic, but it goes as close as it can by orbiting with the earth hugged up against the surface.
|
OddEye
Registered: 10/08/04
Posts: 440
Last seen: 2 days, 32 minutes
|
Re: Gravity so weak....? [Re: johnm214]
#13266061 - 09/29/10 07:32 PM (2 years, 7 months ago) |
|
|
Quote:
johnm214 said:
Quote:
OddEye said:
The only thing I don't understand about this whole thing is why the fuck do planet don't crash into each other and orbit each other instead. I actually have a "good" understanding of the universe, but I still dunno that lol. Is it the electromagnetic field?(doesn't rly make sens since only earth has one)
They do crash into each other, you just aren't watching long enough : )
The orbiting is because the planets have momentum with respect to the star, and this must be conserved. If you imagine a planet strolling along that suddenly gets 'captured' by a star's gravitational field (so to speak), their original relative motion doesn't disapear. This is what results in the orbiting: the planet has angular momentum with respect to the star because it had velocity with respect to the star. This is pretty much the same as one of those coin-drop funnels that have the coin orbit the funnel's hole- it doesn't drop directly in the hole because of the angular momentum. As friction causes the momentum to decrease, the orbit does too, and eventually the coin falls in the hole and the planet into the star.
(think of the tangential velocity of the planet in an orbit, it is in a direction which would take it away from the star and this momentum is what keeps it from simply dropping like a stone from our outsider's perspective).
Interesting, it makes sens! Thanks!
--------------------
I'm at the highest peak, still glad the meak is understandin' me
Artillery, thoughts of killin' me is just a fantasy
The man in me is ready for war, like Holyfield-Tyson IV
| |
|
|
You cannot start new topics / You cannot reply to topics
HTML is disabled / BBCode is enabled
Moderator: Lana, trendal, Diploid, automan, johnm214
413 topic views. 1 members, 7 guests and 0 web crawlers are browsing this forum.
[ Toggle Favorite | Print Topic ]
| | |
|
|
|
Images only 
Threaded
Previous
Index
Next
Shop for: 
Edit 
Reply 
