Newton's Law of Gravity can predict gravitational lensing
william chan
Posts: 1,326
Some Food for Thought.
Everybody thought that it was Einstein's General Theory of Relativity about mass distorting space-time that first predicted that light can be bent by gravity.
However, if we consider light as balls of photon which has a mass, then by applying
F = G(M1M2/R*R) it becomes common sense that gravity would surely attract and bend light.
General Theory of Relativity is only one of many models that can predict gravitational lensing.
Why should we be so lucky that the first model that we can think of becomes the truth?
Everybody thought that it was Einstein's General Theory of Relativity about mass distorting space-time that first predicted that light can be bent by gravity.
However, if we consider light as balls of photon which has a mass, then by applying
F = G(M1M2/R*R) it becomes common sense that gravity would surely attract and bend light.
General Theory of Relativity is only one of many models that can predict gravitational lensing.
Why should we be so lucky that the first model that we can think of becomes the truth?
Comments
Hence the fatal flaw. Photons do NOT have mass.
A lot of people assume that E=MC^2 is the correct formula to apply here, which would mean that because the photon has energy, then it must have mass. But it doesn't apply because E=MC^2 isn't the full equation... it only applies when the mass has zero momentum (Rest Mass is the term, like Tor said.) The full equation is E^2 = M^2C^4 + P^2C^2. If the photon was at rest, then P=0 and our formula becomes E=MC^2. Instead, however, for a photon with momentum but no mass, M=0... and our formula is actually P=E/C.
Bill
For example, 2 protons crashing into each other at high speed can produce anti-electrons.
Newton's equation can be expanded to be used for non-rest mass.
<sigh> You are my hero. I want one!
I only minored in physics but I distinctly remember someone asking a professor about this exact thing. Using the attraction from gravity does not give the correct answer (to the about light is bent).
All of our general relativity questions were qualitative. I never learned the math necessary to calculate quantitative results for general relativity (I got pretty good at special relativity equations though).
Duane
Duane:
Physics was one of my majors and the teacher went far beyond the MIT Physics book.. making every day a quantitative dream come true. As I recall, the chalk board running across the full width of the big room was not enough to contain all the equations.
At first, I turned 8 1/2 x 11-inch paper sideways to print long equations using a hard lead pencil and very tiny numbers. By the time I was senior, I was much smarter and used the back side of recycled very wide computer printer paper from a big IBM 360.
Spiral_72:
I think you should have one. Do you have any smaller telescopes so far? I began with a 30mm scope in grade school, then years later a view of Saturn's rings through an Edmunds 3-inch reflector telescope got me started! It was like an addiction and a need for increasingly larger telescopes to see more. The next one was a 4.25-inch, some refractors, and then I made more, several 8-inch Newtonians, 8-inch Schmidt, 12.5-inch reflector, 40-inch reflector, and the massive 50-inch.
BTW, Celestron is offering a 3-inch reflector telescope which can be purchased from Amazon.com for $35. Do a search for "Celestron FirstScope."
http://www.amazon.com/Celestron-21024-FirstScope-Telescope/dp/B001UQ6E4Y
Wow, it sounds like you have some neat toys at your disposal
I used to use my uncle's "Telescope" when I were about 8yrs old to see Jupiter and Saturn's rings..... and of course the moon. This "Telescope" was actually an old 60mm rifle scope on a camera tripod.
Now I have a 8" reflector on an equatorial mount. I use a Canon Rebel 8Mp, with a single axis clock drive. It does alright.I have some images here: http://s250.photobucket.com/albums/gg256/spiral_72/
Spiral_72: That's a really great page of your astro photos. Thanks for sharing! I did telescope testing with the Celestron FirstScope last night and will post the results later today on this page: http://forums.parallax.com/showthread.php?124495-Fill-the-Big-Brain/page71