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Author Topic: Does gravity have an effect light?  (Read 6844 times)

Offline qazibasit

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Does gravity have an effect light?
« on: 01/07/2004 01:11:53 »
does the gravity effects on light and if not than why light didnt return from the black hole and as the gravity of black hole has too much gravity that it can compress the whole of the space ship to a single cell.
« Last Edit: 07/07/2004 01:24:55 by Exodus »


 

Offline neilep

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Re: Does gravity have an effect light?
« Reply #1 on: 01/07/2004 02:32:30 »
I'm sure I've seen or read somewhere that extreme gravity does in fact have an effect on light, to the point where light bends so much that it acts as a lens.....I'm sure there is someone here who can answer this one far more precisely.....and the very fact that ' Black Holes' are called so, is purely because the gravity is so strong that the light can not escape, therefore making a ' black hole'.

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Offline tweener

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Re: Does gravity have an effect light?
« Reply #2 on: 01/07/2004 03:45:35 »
Yes, gravity does effect light.  A black hole is the ultimate example of this because it is an area of such high mass density that no light can escape.  Other examples are gravitational lensing, where the light from distant galaxies passing close to other galaxies or stars on the way to our telescopes is bent.  This effect has been observed and measured and is in agreement with Einstein's theory of General Relativity.

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Offline qazibasit

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Re: Does gravity have an effect light?
« Reply #3 on: 06/07/2004 00:16:18 »
well i think we all know what is the mechanism and logic of formation of black holes.
 

Offline Ultima

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Re: Does gravity have an effect light?
« Reply #4 on: 21/07/2004 20:57:20 »
I didn't think it effected the light directly? In as much as the light continues in a straight line but space itself is warped??[:I] probably got the wrong impression when i read a book about it.

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Offline tweener

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Re: Does gravity have an effect light?
« Reply #5 on: 22/07/2004 16:54:25 »
quote:
Originally posted by Ultima

I didn't think it effected the light directly? In as much as the light continues in a straight line but space itself is warped??[:I] probably got the wrong impression when i read a book about it.

wOw the world spins?



I probably used the wrong words in my post, so I stand corrected.  This is a more accurate description, but has the same observable consequence on the light.

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Offline neilep

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Re: Does gravity have an effect light?
« Reply #6 on: 27/07/2004 18:51:21 »
If you check one of my latest postings on Science Photo Of The Week, you'll see a prime example of gravitaitional effected light AKA gravitational lensing.

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Offline qazibasit

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Re: Does gravity have an effect light?
« Reply #7 on: 28/07/2004 11:33:22 »
can we perform this experiment to check the effect of gravity on light in laboratory and can we change the path of light. is their any way.
 

Offline neilep

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Re: Does gravity have an effect light?
« Reply #8 on: 28/07/2004 12:18:54 »
That's a great question Gazibasit....I'm NOT a physicist at all, but I wonder if such an experiment is possible....one would have to create (i suppose) a strong gravitational effect somehow.....I just don't know myself and will leave this one for the experts to answer......I know there have been experiments that prove the relationship between time and gravity using atomic clocks in airplanes etc, I wonder if a similar approach can be used for light.

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Offline gsmollin

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Re: Does gravity have an effect light?
« Reply #9 on: 28/07/2004 14:41:05 »
It has been done. I don't remember who gets original credit, but I seem to recall this experiment has been performed at Cambridge. Anyway, all you need is an elevator shaft, and equipment to measure the gravitational red-shift of light going up the elevator shaft.
 

Offline tweener

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Re: Does gravity have an effect light?
« Reply #10 on: 29/07/2004 03:12:22 »
I thought the experiment had been done with sun occluding distant galaxies (during an eclipse).  The amount the light from the galaxy was "bent" by the sun's gravity was measured and agreed perfectly with the prediction by general relativity.

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Offline qpan

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Re: Does gravity have an effect light?
« Reply #11 on: 29/07/2004 11:53:17 »
Yeah - i do remember an article similar to what tweener described.

gsmollin - are you sure that we have sensitive enough equipment to measure the redshift of light going up an elevator? The Earth's gravitational field is extremely weak, and we're only talking tens of metres in terms of elevator shaft length! The differences in time with and withought a red shift due to gravity would be truely miniscule!

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Offline gsmollin

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Re: Does gravity have an effect light?
« Reply #12 on: 30/07/2004 03:18:10 »
Yes, it was done at Harvard. An isotope of iron, which has a very narrow emission line was used. Two samples of the isotope were used, one an emitter, the other a receiver. When the two samples were side-by-side, the emitted radiation was received by the receiver sample. As the receiver was raised above the emitter in the elevator shaft, and the emitted light red-shifted, the receiver reduced its absorption of the red-shifted light.
 

Offline gsmollin

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Re: Does gravity have an effect light?
« Reply #13 on: 30/07/2004 03:22:55 »
The gravitational bending of the starlight during an eclipse was the first "verification" of General relativity, and made Einstein a household word. The main problem was that this experiment had poor accurcy. Since then, many better experiments have ben devised, many using spacecraft. The most accurate one of all used the transmitters of the Viking spacecraft on Mars. The reason this was best, was because a spacecraft on the surface of a planet has its velocity kept very stable by the mass of the planet.
 

Offline Titanscape

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Re: Does gravity have an effect light?
« Reply #14 on: 14/08/2004 16:40:18 »
I ponder and picture the idea of liquid light flowing over the surface of a black hole. Is it possible, do you think?

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Offline OmnipotentOne

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Re: Does gravity have an effect light?
« Reply #15 on: 17/08/2004 01:17:50 »
Wait wait Ultima got me confused, is the density of the object warping the space the light travels through, or the photon itself?  Or did i just get everything confused in general.  A nice refresher would be appreciated.

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Offline tweener

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Re: Does gravity have an effect light?
« Reply #16 on: 17/08/2004 03:23:59 »
Ultima has one way of looking at the situation.  The mass warps the spacetime continuum and the photon follows the curvature of the space.  A simpler way to look at it is that the photon is travelling along and gets attracted to the massive object by its gravity.  

I'm sure gsmollin can explain it better - he knows a lot more than I do.

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Re: Does gravity have an effect light?
« Reply #16 on: 17/08/2004 03:23:59 »

 

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