And God said, "Let there be light," and there was light
Interesting coincidence, huh ;)
Physicists discover that gravity can create light
91–100 of 108 posts
Re: Physicists discover that gravity can create light
#92Earlier quoted context omitted.
Ok, why all the downvotes even after starting a healthy discussion thread? And can someone help me understand in layman terms how current physics posits that gravitation is generating light or even hawking radiation?
Gravity couples with anything that carries energy (in more precise terms with the energy-momentum tensor). Photons carry energy. Therefore there is interaction between photons and gravity. In particular, you can write Feynman diagrams for the interaction between a quanta of gravity (a graviton) and a photon. Some of the simplest ones look like this: https://www.researchgate.net/figure/Tree-level-Feynman-diagr... Ther…
Thank you so much, this was the explanation I was looking for.
Re: Physicists discover that gravity can create light
#93Gravity makes heavy; gravity makes light.
Re: Physicists discover that gravity can create light
#94All this time I thought that gravity creates heavy, not light.
It’s the light side of the gravitational force, bringing balance to the universe.
Re: Physicists discover that gravity can create light
#95All quantum fields have their vacuum energy fluctuations. When we change the parameters of the space (e.g. stretch or compress it), the current state is no longer the ground state but becomes a so-called squeezed vacuum state. This effect is used in laser physics to "split photons" in spontaneous parametric downconversion. That is, an intense laser changes the refractive index of a medium periodically. These oscillat…
That's a nice explanation. Finally some high falutin physics I can understand in terms of paramps.
I, on the other hand, looked at this and thought "I know these words". I don't think a cup or to of coffee is going to help.
Re: Physicists discover that gravity can create light
#96Re: Physicists discover that gravity can create light
#97Thomas Pynchon was ahead of his time with his book title https://en.wikipedia.org/wiki/Gravity%27s_Rainbow
Isn’t that about the arc a rocket makes?
He picked a metaphor with many possible interpretations : )
My main take away is something like "gravity" is ~ death / extensional pain of life & the "rainbow" is the beauty that exists/we make under that
Re: Physicists discover that gravity can create light
#98Earlier quoted context omitted.
Or gravity is just bending of space around a mass. And not a force.
Not a physicist, but how do you get something to bend without a force exerted upon it?
the simplest way to describe it is that an object in freefall moves in geodesic in spacetime, which is a is not straight line in 3dimensional classical physics but produces gravitational motion.
https://en.wikipedia.org/wiki/Geodesics_in_general_relativit...
The basic idea is that depending on your frame of reference, you might experience what is called a fictitious or psuedo force that disappears in a more simple frame of reference. Examples of these include centrifugal force, the Coriolis effect.
https://en.wikipedia.org/wiki/Fictitious_force
Einstein's great revelation in the theory of general relativity was that there was no difference between gravity and free fall - which is called the equivalence principle.
https://en.wikipedia.org/wiki/Equivalence_principle
In special relativity, einstein's theory had a preference for inertial frame observers where the observer essentially became the origin of coordinate system to map space by, but in general relativity einstein does away with inertial frames as privileged, and an observer is literally decided by what light it can see, and their coordinate system cannot be universal because of curved space.
https://en.wikipedia.org/wiki/Inertial_frame_of_reference#Sp...
https://en.wikipedia.org/wiki/Observer_%28special_relativity...
Re: Physicists discover that gravity can create light
#99Re: Physicists discover that gravity can create light
#100We know that light can create gravity, so it stands to reason that there should be a reciprocal relationship!
E=mc^2. If you have enough energy, in any form, it is equivalent to mass and should disturb spacetime equivalently.
Light can also be used to push objects. Interestingly, sunlight exerts a pressure of 6.56e-10 [psi = lbs/in^2] or 4.53e-6 [N/m^2] on the Earth. This is roughly 5.75e8 [N] or 46 Space Shuttle SRBs. The gravitational force between the Earth and Sun is 3.52e22 [N], or + ~14 orders-of-magnitude.
Objects on Earth at the rotational equator at MSL weigh 0.2% less than at the rotational poles due to the centrifugal force.