On Curved Space

[LeRepteux]

Hi everybody,

 

Here is a drawing representing two light rays curved by the sun's mass: a blue ray coming from a star that brushes past the sun, and a red ray coming from the periphery of the sun itself.

 

 

The two rays are parallel when they begin to travel together at the sun's periphery (dotted red and blue arrows), and they thus hit the earth later at the same angle since, being very close to one another, they almost suffer the same curvature (plain red and blue arrows), what gives to the earth observers the impression that both rays come from the same spot in the sky (dotted red and blue lines that lead to the dotted star).

Einstein predicted that the ray coming from the star would get curved by the presence of the sun, but without noticing that the ray from the periphery of the sun itself should also get curved, so he did not realize either that the sun would look wider during this observation, and that he thus would have to shrink it on the mapping of the sky made when the sun was not there to curve the rays.

If he had shrunk his sun on the mapping made when the sun was on the other side of the earth, it would have hidden the same stars than the ones that were hidden during the eclipse, so he could not have concluded that light was effectively curved by gravitation as he had predicted, but instead, that the sun's presence was affecting the direction of the rays in such a way that a mapping made in it's presence kind of widened the sky compared with the one made when it wasn't there.

Notice that this reasoning does not contradict the observations, it only contradicts the explanation of the observations, reason why I placed it on a science forum, but if it's right, then there must be another explanation, and I did not find it yet, except that gravitation kind of widens the sky when our observations are made from a much less massive body than the one we are gravitating around, which means that it could be the real acceleration of the earth observers towards the sun at the microscopic level that would affect the direction of the rays. So far so good, but as I said, it doesn't seem to work, because moving at an angle through a light ray should bend it in the direction of the movement as for the aberration of star light, which would shrink the sky during an eclipse instead of widening it as the observations show, so I am still looking for an explanation.

Anybody finds the idea interesting? Anybody thinks that the rays coming from the sun should also be curved by the gravitation of the sun?

Edited September 26, 2015 by LeRepteux

[phillip1882]

well, you couldn't see a star directly behind the sun because of this, i would agree. but you can still see stars slightly behind the sun. you're correct, the suns rays are also curved, which means the sun appears a little bigger than it actually is. but this size increase isn't sufficient enough to block a a star light trajectory if its in the right spot.

[LeRepteux]

Hi phillip,

 

If the sun's light is also curved by the gravitation of the sun, it changes Einstein's predictions, because the only way to prove the curving is to use the diameter of the sun as measured optically, and superpose it to the mapping of the sky when it isn't there to curve the rays. If the sun's light is really curved, then it increases the sun's diameter, which has thus to be shrunk on the mapping made when it isn't there. But if we do that, it won't hide the stars that Einstein predicted it would, the ones that, as you say, were just at the right spot, and we would thus have to find another explanation than bending to explain the observations.

Edited September 29, 2015 by LeRepteux

[LeRepteux]

I think I found a way to test my point!

If the sun's light was really curved by its own gravity, it follows that a spiral galaxy light would also be, which means that its apparent diameter would also look larger than it really is. In the case of galaxies, the measure of their rotational speed made at different heights would thus be attributed to larger heights than the real ones, which could explain the lack of gravitational pull that we attribute to Black Matter. Anybody wants to help me with the maths?

[LeRepteux]

I found a discussion about that on another forum, here is an insight on the maths and my answer after:

 

Janus said...

let's work out an example and see if this is even feasible. We'll assume a galaxy 100,000 light years across with a mass of 100,000,000,000 solar masses which is 1 billion light years away.

The light from a source behind this galaxy and just skimming its edge, would by gravitational lensing be deflected by 0.258 sec of arc. Since 1/2 of this deflection occurs on the inbound path, the most we can expect light coming from a star at the edge to be bent on its outward path to us is 0.129 sec of arc.

At a distance of 1 billion light years, this equates to an apparent displacement of ~625 light years ( meaning the galaxy would appear to be 50,625 light years in radius instead of 50,000.)

Calculating the difference in orbital speed at 50,000 vs. 50625 light years produces orbital velocities of 167 km/sec vs. 168 km/sec.

If we work out how much extra mass it would take to make that 1 km/sec difference at a fixed radius of 50625 light years, it works out to a difference of ~1.2%, or far short of the amount of dark matter needed to make up for the missing mass according to the actual orbital velocities we measure.

In addition, gravitational lensing in fact gives us additional evidence for dark matter. Because of the extra mass due to DM, the light passing galaxies bends more than and differently from what we would expect from just the matter we see.

On top of that, we have the case of the Bullet Cluster, in which dark matter has been "knocked loose" from the visible matter in a collision between galaxy clusters. In this situation we see gravitational lensing of objects behind the cluster where there is no visible matter to cause it.

Galaxy rotation curves may have set us on the road to dark matter, but there has been a great deal of other supporting evidence uncovered since the first step on that path.

 

 

I answered...

 

Thanks for the calculations Janus. So you came to the conclusion that this kind of bending cannot account for dark matter, but it sure can account for the flatness of the curve though, because both the exaggerated speed and the apparent bending are caused by the same importance of the curved space at the same distance from the center of mass, so if we do the calculations for different distances, we should get a rotation curve which would be similar to the predicted one, but a bit higher on the graph. Am I right?

http://www.thescienceforum.com/astronomy-cosmology/49499-can-dark-matter-optical-illusion-caused-gravitational-lensing.html#post658865

 

Janus accepts that the light from the galaxy might be curved by its mass, so he does the maths, and conclude that there would not be enough curving to justify the observed speed. I answer him that the curving of light should be proportional to the orbital speed since both are due to the same curved space. I can't see his answer since I have been banned for two weeks for having insisted with this type of curving, but I still think that the new speed/distance curve should follow the predicted one, and I have an answer for the speeds still being too fast at the corrected distances. Somebody wants to hear it?

Edited October 22, 2015 by LeRepteux

[phillip1882]

hmm sure i doubt ill agree, but post away, ill see if i can find a flaw.

[phillip1882]

If the sun's light was really curved by its own gravity, it follows that a spiral galaxy light would also be, which means that its apparent diameter would also look larger than it really is. In the case of galaxies, the measure of their rotational speed made at different heights would thus be attributed to larger heights than the real ones, which could explain the lack of gravitational pull that we attribute to Black Matter. Anybody wants to help me with the maths?

 

i'm fairly confident the sun's light is curved by it's own gravity, it would have to be since light is considered at least in part to be a particle, and all particles, even mass less ones such as light, are considered to be effected by gravity. i have no idea how to calculate how much curvature the would be however, and i agree galaxies would also appear to be larger than the really are because  of this, but i doubt this would answer the dark matter paradox.

 

i should give fair warning here as several users already know, i don't particularity care for Einsteins theory, i personally disagree with it. there are other ways of explaining our observations with light other than resorting to warped space time.

Edited October 22, 2015 by phillip1882

[phillip1882]

i head an idea, using keplers third law of plaentary motion, v^2 r = k we can caluate how much curvature there will be.

for the sun, k = 3,250,000,000,000,000,000 m^3/s^2

light = (300,000,000 m/s)^2 = 90,000,000,000,000,000 m^2/s^2  = 361 m. so we can  approximate that the sun appears 361 meters larger than it really is.

Edited October 23, 2015 by phillip1882

[LeRepteux]

Hi Philip,

 

Can you calculate if these extra meters give an optical angle of about 1.7 arc sec seen from the earth? I'm afraid it is much too small to match that data though. Anyway, sketching a speed curve for galaxies without accounting for light bending should flatten the curve, and its exactly what we get, but as Janus points out, it is not enough to account for the whole increase. My explanation for this supplementary increase is simple, but its nevertheless difficult to grasp. I think that if we retrieve the redshift from the equations, it should give the right speeds. A receding of galaxies not only lowers the frequencies of their light, but it also slows their normal rotation periods, so we have to increase them in the equations. If we took them as they are, I think it might give the right speeds. But it follows that we would have to look for something else than expansion to explain the redshift. 

Edited October 23, 2015 by LeRepteux