spacetime

[alextwo]

was watching tv about Einstein's curved spacetime and the experiments during eclipses. How do we know that spacetime is curved rather then simply light bending because of gravity? I think it's just another way of saying the same thing. Please explain.

[swansont]

They are the same thing. Relativity explains that bending with geometry, i.e. space not being described by a Cartesian (flat) system.

[MolecularEnergy]

Well, in 1919, Arthur Eddington took pictures of photon energy bedning round the star we call the sun. This bending was seen to be evidence, if not the proof of relativity that the curvature of spacetime was the effect of a distortion in spacetime itself, or the presence of matter, if you will.

[thedarkshade]

How do we know that spacetime is curved rather then simply light bending because of gravity?.

Spacetime is curved near massive objects, and when a photons moves near that massive object, it bends becuase the spactime is curved. The photon will still me travelling in a straight line, but that line is passing through curved space, which makes it look like it bends.

[swansont]

While these last two posts are certainly true, I think they miss the question of the OP. Gravity manifests itself as the curving of spacetime. They are indeed the same thing, which was the conjecture.

[granpa]

gravitational time dilation would also cause light to bend (refract) around massive objects.

[north]

Spacetime is curved near massive objects, and when a photons moves near that massive object, it bends becuase the spactime is curved. The photon will still me travelling in a straight line, but that line is passing through curved space, which makes it look like it bends.

 

this so called space-time is curved is very , very , very misleading

 

light is curved or bends because of the energy and/or matter in that region of space

 

neither space or time has ANY and I mean ANY substance associated with them

 

which means that neither space or time can AFFECT anything at all

[iNow]

Nonsense.

 

You may as well have said that purple unicorn farts cause erections in leprechauns. Let's see some evidence in support of your claims, north.

[north]

Nonsense.

 

You may as well have said that purple unicorn farts cause erections in leprechauns. Let's see some evidence in support of your claims, north.

 

I already have in other threads I'm sure of which you are aware

 

first lets look at space

 

can you give me a block of space , without confinment ( such as walls )

 

go outside and bring me a block of space and present it to me as a seperate block of space to the space of which you are in

 

can you do that ?

[iNow]

You cannot avoid the request for a reference, citations, or supporting mathematics with a question to me. Please address my request or stop posting. I want to remind you that you're posting in a physics forum, not a metaphysics or philosophy forum.

[north]

You cannot avoid the request for a reference, citations, or supporting mathematics with a question to me.

 

I'm not avoiding reference

 

but who do I reference too ?

 

who has thought the way I do about the subject ?

 

no one that I know of

[swansont]

gravitational time dilation would also cause light to bend (refract) around massive objects.

 

Not "also" since gravitational time dilation stems from the same effect.

 

this so called space-time is curved is very , very , very misleading

 

light is curved or bends because of the energy and/or matter in that region of space

 

neither space or time has ANY and I mean ANY substance associated with them

 

which means that neither space or time can AFFECT anything at all

 

You appear to agree that light bends.

 

Then, end of story. One way to represent that is geometrically, i.e. non-Euclidean space.

 

Any suggestion that relativity is incorrect (if that's what you are suggesting) should be discussed in its own thread. Not here.

[north]

Not "also" since gravitational time dilation stems from the same effect.

 

 

You appear to agree that light bends.

 

yes

 

 

Then, end of story. One way to represent that is geometrically, i.e. non-Euclidean space.

 

not end of story

 

yes one way is to represent this geometrically

 

but geometrics does not go deep enough

 

geometrics merely describes the consequence of energy/matter angles but does not tell me why ?

 

 

 

 

 

Any suggestion that relativity is incorrect (if that's what you are suggesting) should be discussed in its own thread. Not here.

 

light bends BECAUSE of the ENERGY and /or matter in space

[thedarkshade]

light is curved or bends because of the energy and/or matter in that region of space

Dude, ligh is curved becuase it is going through curved space, which is a manifestation of gravity.

"Gravity manifests itself as the curving of spacetime." -swansont

 

who has thought the way I do about the subject ?

 

no one that I know of

Is that relevant in determing whether you post was true or not?

[granpa]

does spacetime curve or do objects in a gravitational field simply shrink and become time dilated like they do when moving near the speed of light?

 

since light cant shrink then it would only be affected by time dilation. hence post 6.

Edited December 22, 2008 by granpa

[thedarkshade]

does spacetime curve or do objects in a gravitational field simply shrink and become time dilated like they do when moving near the speed of light?

have a look at post #5:-)

[swansont]

light bends BECAUSE of the ENERGY and /or matter in space

 

Which brings nothing new to the discussion. Matter and energy bend space/cause gravity. I'm failing to see why this is being repeated in umpteen different ways as if some new insight were being delivered. It would seem that you think your statement is saying something new.

 

does spacetime curve or do objects in a gravitational field simply shrink and become time dilated like they do when moving near the speed of light?

 

since light cant shrink then it would only be affected by time dilation. hence post 6.

 

Light's path changes because of the curvature. The excess path due to this, as viewed by someone in flat spacetime, is one way of accounting for the time dilation (Shapiro delay)

[granpa]

if one clock is deeper in a gravity well than another then they will tick at different rates. 'excess path' cant account for that.

[swansont]

if one clock is deeper in a gravity well than another then they will tick at different rates. 'excess path' cant account for that.

 

I was discussing the path of photon travel and last time I checked stationary clocks weren't photons.

 

Time dilation is a gravitational effect. It's misleading to explain the warping as being caused by time dilation; all of the effects are from a common cause.

[granpa]

that doesnt make any sense. why would gravitational time dilation for light be any different than for a clock?

 

I'm now (typo for 'not') explaining warping as being due to time dilation but if it is objects that shrink,not space that stretches, then light cant shrink so it can only be affected by time dilation.

Edited December 22, 2008 by granpa

[iNow]

As addressed already, time dilation is an effect, not a cause.

[granpa]

As addressed already, time dilation is an effect, not a cause.

meaningless.

 

cause of what? time dilation causes many things. gravitational redshift for instance.

[iNow]

cause of what?

Oh, for the love of Thor, granpa. My reply was in response to your post, so clearly I was referring to "warping being due to time dilation." Please look up the word context and try again when you have.

 

 

I'm now explaining warping as being due to time dilation but if it is objects that shrink,not space that stretches, then light cant shrink so it can only be affected by time dilation.

[granpa]

whoops. major typo.

 

that doesnt make any sense. why would gravitational time dilation for light be any different than for a clock?

 

I'm now (typo for 'not') explaining warping as being due to time dilation but if it is objects that shrink,not space that stretches, then light cant shrink so it can only be affected by time dilation.

Edited December 22, 2008 by granpa
multiple post merged

[iNow]

Thanks for the clarification. That certainly helps, but I still wonder about your closing words: "[light] can only be effected by time dilation."