Shapiro Effect and Gravitational Lensing

In summary, the conversation discusses a website that proposes alternative explanations to BBT and the doppler effect, specifically through the use of the Shapiro effect and gravitational lensing. The participants question the validity of these ideas and debate the constant speed of light in a vacuum. There is also mention of the limitations of current models and the need for further mathematical analysis.
  • #1
shrumeo
250
0
I have been searching for alternatives to BBT and the doppler effect to explain everything, and have been dissapointed to find a lot of crackpots out there. I have recently found this website:

http://www.geocities.com/newastronomy/Index.htm

and the thing makes all kinds of sense (to my limited intellect)

But, there are a few problems I have with the explanation of "extra" gravity from stars and the explanation of neutron stars.

Are there any real physicists out there that are willing to debunk these ideas?
I've seen physicists "ruling out" the Shapiro Effect for redshifts on their websites, but their explanations were always "over my head". Can anyone do it in semi-plain english??

Also, what about his ideas about gravitational lensing ? I think it's pretty cool and makes a little too much sense. Am I blind?? :confused:
 
Astronomy news on Phys.org
  • #2
I have not read the whole webpage, but only the part describing the hypothesis of cosmological redshift due to the Shapiro effect.

As far as I know, a remote observer would indeed measure a modification of the speed of light when light passes through a gravitational potential, since it experiences a time-delay wrt to a trayectory through empty space.

But I am not sure that this will produce a redshift. To calculate the redshift due to gravitation one has to make use of the formula for gravitational redshift derived from a Schwarzschild spacetime. This will lead to a prediction of redshift as well as blueshift when light falls into and comes out from potentials.

May be I am missing something.

Regards.
 
  • #3
i think the gravitational lensing ideas on this webpage havent' been totally thought out, mathwise especially.

wouldn't there be at least a little distortion? smudging, arcing, that type of thing?

and OH! I guess I didn't read carefully. The shapiro effect is on the SPEED of the light? hmm, i guess I was under the assumption that light in a vacuum has ONE speed, period. I thought it reduced the energy! here i was thinking everyone thinking doppler effect and expanding space were retarded.

I think this webpage is just some bozo like me, who doesn't do this for a living, but tries to wrestle with the concepts without doing any of the math.
 
  • #4
shrumeo said:
The shapiro effect is on the SPEED of the light? hmm, i guess I was under the assumption that light in a vacuum has ONE speed...
Yes, locally always c, but seen from far away (wrt a potential) one will measure a differend speed as c.

Regards.
 
  • #5
again, i thought that light in a vacuum went c
in ALL inertial reference frames and wrt any other reference frame
 
  • #6
if you use 'c' as the local reference frame, it solves every objection to what is observed. this is not an arbitrary measure. as a predictive model, it has flaws. the singularity at the beginning of time breaks down the math of all currently known models.
 
  • #7
shrumeo said:
again, i thought that light in a vacuum went c
in ALL inertial reference frames and wrt any other reference frame
This is true in a globally flat spacetime, but I think a Schwarzschild spacetime is usually assumed in order to calculate the gravitational redshift and the Shapiro effect. In a Schwarzschild spacetime there is a dependence of the speed of light with the gravitational potential when measured by distant observers (but not when measured in a local experiment). Regards.
 

1. What is the Shapiro Effect?

The Shapiro Effect, also known as the Shapiro Time Delay, is a phenomenon in which light is delayed as it passes near a massive object, such as a star or planet, due to the curvature of spacetime caused by the object's gravitational field.

2. How does the Shapiro Effect relate to General Relativity?

The Shapiro Effect is a consequence of Einstein's theory of General Relativity, which describes how massive objects curve the fabric of spacetime. According to this theory, light traveling through curved spacetime will follow a curved path, resulting in a delay in its arrival time.

3. How is the Shapiro Effect measured?

The Shapiro Effect is typically measured by comparing the arrival times of light from a distant source, such as a pulsar, when it passes close to a massive object, such as a white dwarf or neutron star. The difference in arrival times can then be used to calculate the magnitude of the time delay caused by the object's gravitational field.

4. What is Gravitational Lensing?

Gravitational Lensing is a phenomenon in which the path of light from a distant object is curved by the gravitational field of an intervening massive object, such as a galaxy or cluster of galaxies. This can result in the appearance of distorted or magnified images of the distant object.

5. How is Gravitational Lensing related to the Shapiro Effect?

The Shapiro Effect is a type of gravitational lensing, but it is specifically caused by the time delay of light passing through a gravitational field. Gravitational lensing can also occur through the bending of light, resulting in multiple images of a single source, which is known as strong lensing. Both the Shapiro Effect and strong lensing are important tools for studying the properties of massive objects and the nature of gravity.

Similar threads

  • Cosmology
Replies
4
Views
1K
Replies
2
Views
1K
  • Astronomy and Astrophysics
Replies
13
Views
1K
  • Astronomy and Astrophysics
Replies
5
Views
2K
Replies
18
Views
2K
  • Special and General Relativity
Replies
6
Views
1K
  • Astronomy and Astrophysics
Replies
19
Views
4K
  • Astronomy and Astrophysics
Replies
12
Views
4K
Replies
72
Views
5K
  • Special and General Relativity
Replies
11
Views
1K
Back
Top