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Is gravity a force?
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by AnimeLover
on 2006-10-28 08:33:52
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| Hello i am new to this forum and phys...so anyway i was wondering is gravity a force? i mean if it is a force, how do you explain that black hole does not allow light to escape? wont it be better to define it as curvature of mass?? |
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Re: Is gravity a force?
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by
on 2006-10-28 12:51:53 |
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you mean "curvature of space-time due to mass". yes, that is one way of thinking about gravity. another way of thinking about it is as a force. when considering gravity as curvature of space-time, we can represent a black hole as a rip in space-time. the fabric is bend downwards so steeply that at the event horizon, it is vertical. any particle near the event horizon will roll down into the funnel shape like a coin dropped into in one of those clever little gadgets. 
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Re: Is gravity a force?
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by SuicidopoliS
on 2006-10-28 16:29:42
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AnimeLover said: "i mean if it is a force, how do you explain that black hole does not allow light to escape?" Well, you practically gave the answer yourself... It's a force, and it so darn strong it literally prevents light to get away. A "Black Hole" is in fact anything but a hole. It's a mass so concentrated that it generates such a strong gravity field that, indeed, even near-massless photons, the "light particles", can't escape. .oO° Life's THE CURE, the rest are details! °Oo. |
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Re: Is gravity a force?
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by ... I don't need one
on 2006-11-06 19:57:37 (edited 2006-11-06 20:15:46)
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Black holes contain a mass of multiple times of the sun, and that is why light cannot eschew (or avoid) it. Oh, and we might use this force to communicate with other universes. It is called the gravaton or something like that. It is only a matter of time and technology. Here's a website for information : Black Holes Here's another website for information : Gravity
... I don't care...
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Re: Is gravity a force?
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I heard somewhere that there are four universal forces, in order from weakest to strongest: Gravity Electromagnetic Weak Nuclear Strong Nuclear I also heard that once you reach certain temperatures, the differences between different forces break down. I heard it on an educational video once, but does anyone have a better description or good references?
>,>; Did I just say that...?
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Re: Is gravity a force?
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by
on 2006-11-06 22:46:28 |
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hyperphysics has a great page with lots of information on the 4 forces.
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Re: Is gravity a force?
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by
on 2006-11-07 00:07:44 |
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Well, on teh 4 forces, gravity is the weakest by far. But I feel liek discussing black holes, so just visit the afformentioned site for info on the forces. In the matter of black holes, it is a misconception that light cannot escape. In actuality, there are two instances where matter excapes form a black hole, and both are continuous. First of all, matter about to enter a black hole has a chance of being projected back into space a the last possible moment. This creates a plume of matter racing away from the black hole and is how black holes are indentified, aside form their gravitational impact. Aside from this, black holes actualy do loose a small amount of matter over time that has actualy entered into the "singularity' that is a black hole. The rate is incredibly small, but matter can and does escape a black hole. I suppose that does not actualy adress light because even though it is a particle, it has no mass and so is not matter. With light, you have to realize that light is energy just like that emitted by a microwave, except the wavelegnths are shorter. It is also important to note that energy, such as visible light, is absorbed by bodies and re-emitted at a different wavelegnth based on the energy of the emitting body. The earth for example absorbes visible light and emittes the enegy as longer-wavelegnth-than-visible light. A black hole can do the same thing. If the energy is emitted, it would not be as "light" but a different form of radiation. However, the energy required for a sigularity is enormous, so the energy is in fact utilized and consumed, if you will, much in the same way energy from food is consumed by humans to power basic motor functions. Did that help at all?  The greatest joy is the shameful joy |
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Re: Is gravity a force?
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by SuicidopoliS
on 2006-11-07 12:04:00
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ジャ-麺éºã®é”法æ¦è£…剣分身ã®è¡“ wrote: "Black holes contain a mass of multiple times of the sun, and that is why light cannot eschew (or avoid) it." Correction: the mass itself is not important, it's the massdensity that is. If you take for instance the Earth, which has a mass considerably less then the Sun's mass, and you squeeeesh it together to a sphere with a radius of 0.9cm, you'll have made yourself a nice little Black Hole! And it'll only have taken you 5 940 000 000 000 000 000 000 000 kg ;) "Oh, and we might use this force to communicate with other universes." Well... nobody has yet proven the überhaupt existence of other universes... The point is rather that gravitons are supposed to be living in the extra dimensions String Theory has been predicting. Thus, by observing the graviton ( if we discover one ), we might learn more about those mysterious extra dimensions we can't seem to fully grasp... .oO° Life's THE CURE, the rest are details! °Oo. |