Thursday

February 26, 2015

February 26, 2015

Posted by **Greg** on Wednesday, May 28, 2008 at 11:31am.

- physics -
**drwls**, Wednesday, May 28, 2008 at 1:43pmAlthough the mass m of a photon is zero, if you use Newton's law of gravity with an m term in it and divide by m to get the acceleration towards the sun, the m's cancel out. Compute the integrated impulse to a photon as it passes by the sun at nearest distance d from the center.

I get something like

(G M/cd) cos^3 theta d(sin theta) = (GM/cd)cos^4theta d theta

integrated from theta = -pi/2 to pi/2

M is the solar mass and c is the speed of light

That equals the momentum change toward the sun as the photon passes by. Divide by the forward photon momentum h f/c to get the angular deflection. f is the frequency and h is Planck's constant.

The deflection is proportional to GM/d

This will not give you the right answer; you need Einstein's General Relativity theory for that.

**Answer this Question**

**Related Questions**

Physics / Astronomy - Here is my question: Consider the bending of light by the ...

Physics - Astronomers find that light emitted by a particular element at one ...

Math/Physics - The Milky Way Galaxy is 100000 light years across. The Sun is ...

Physics - The sun is 1.40•10^11m away and light travels at 3.00•10^8m/s. ...

Physics - The sun is 1.40•10^11m away and light travels at 3.00•10^8m/s. ...

Physics - The sun is 1.40•10^11m away and light travels at 3.00•10^8m/s. ...

Physics - The sun is 1.40•10^11m away and light travels at 3.00•10^8m/s. ...

physics - In astronomy, distances are often expressed in light-years. One light-...

physics - The light from the sun is found to have a maximum intensity near the ...

physics - The light from the sun is found to have a maximum intensity near the ...