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ETpro's avatar

If photons have no mass, why are they affected by gravity? (Strange Universe series)

Asked by ETpro (34605points) November 17th, 2010
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RealEyesRealizeRealLies's avatar

Perhaps the conditional is dependent upon having an anti particle, of which the photon has none, allowing it to be simultaneously both wave and particle. But that hypothesis would be rejected if the neutrino theory is ever confirmed.

When considering the lensing effect, one must acknowledge that the photon in is two different places at the same moment. Not only is it bending around the gravity lens, but it is also striking the solid body which creates the gravity lens. Could be a unique property of not having an antiparticle counterpart.

Nullo's avatar

It is my belief that our present model of the universe either needs tweaking or replacement.

Rarebear's avatar

They are actually not affected by gravity. They travel the straightest line. But gravity warps spacetime so that the photon travels along the warped spacetime and therefore the path appears curved.

Rarebear's avatar

And actually, that goes for everthing. Gravity IS the warping of spacetime, so my answer goes for everything. Think of the equivalence principle. You throw a ball in an elevator accelerating at 1g, and it looks indistinguishable from throwing the ball in your living room, and would travel a parabolic arc. But if an outside observer were to visualize the ball and graph out its motion, from the outside observer’s point of view it would be moving in a straight line. The elevator would be what is changing, not the ball. Being in a gravitation field is exactly like standing in an accelerating elevator, but the accelerating is caused from the warping of spacetime.

ETpro's avatar

@RealEyesRealizeRealLies I don’t follow why having or not having an anti-particle would affect the photon’s response to the Higgs mechanism. Could you explain that thought further. Or review what @Rarebear siad. I believe that is the answer.

@Nullo I happened onto this online copy of a lecture by Physicist Lawrence Krauss. ‘A Universe from Nothing’. which I would encourage you to watch and see if it allays some of your concerns with the challenges to the Standard Model. You’ll need a spare hour to listen to it, I am sure you’ll find it enjoyable and revealing, plus get a laugh now and then in the process.

RealEyesRealizeRealLies's avatar

oh no I’m just speculating. I’m with the Rarebear on this one.

You might imagine me to be fascinated about this subject from many angles… so to speak. You’d be correct.

Lucky for all of you that I’m typing from the droid and unable to express details in comfort…;)

ETpro's avatar

@RealEyesRealizeRealLies Ha! If you get back on your workstation and feel called to deliver a wall of words on the subject, please do. I know all too well how time consuming the writing can be, but aI love reading them and pondering the points you raise.

iamthemob's avatar

What @Rarebear said was how I thought it might work – I was muddling over the duality part of it all.

I always like to think of the fabric analogy when it comes to the spacetime questions. For me, I picture spacetime like a canvas stretched over a frame. Massive objects like stars are balls placed on the canvas, creating dips in the once flat surface. Previously, anything traveling in a straight line on the canvas would have continued in a straight line. Once it passes the star (ball), it dips into the warped canvas a bit and the line curves towards it.

An object doesn’t require any mass to be affected by the gravity of these objects, as the objects warp and curve the path on which the object or wave is traveling.

ETpro's avatar

@iamthemob The stretched canvas anology works well for me too. I know we are really dealing with 3 dimensional space-time, 4-dimensional with time included, but it’s the same thing happening in every possible intersecting plane of stretched canvas.

What light is doing as it travels through a gravitational well is similar to what airplanes do in traveling the great circle between two distant points on earth. New York City and Madrid both lie approximately on the 40th parallel north..Nut if a pilot were to fly directly along the 40th parallel (assuming both cities were exactly on it, the plane would travel 3,723.4 miles. whereas the great circle cuts the distance to 3589.50 miles. Light is simply traveling the shortest path like navigators plot for planes.

RealEyesRealizeRealLies's avatar

Interesting canvas analogy. I do large format canvas inkjet printing. It’s different from painting. The canvas is micro porous, whereas the ink sinks into the fabric, becoming a part of it, rather than lying on top in a different layer. Perhaps an analogy is due to depict our physical reality as actually being the artwork within the canvas of space/time.

ETpro's avatar

@RealEyesRealizeRealLies Small wonder astrophysicists speak of the “fabric” of space-time.

RealEyesRealizeRealLies's avatar

Thinking for a moment, the analogy is even more appropriate than a ball floating on top of a canvas as a different layer. Consider instead, that a heavy ink load in one spot will change the dynamic of the canvas differently than a light ink load in another spot. When I stretch these canvas’, I must be careful to overstretch the dark areas, otherwise they wrinkle compared to the light areas.

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ETpro's avatar

@RealEyesRealizeRealLies So that’s where you have been. Off carefully stretching canvasses with highly variable ink loads. Thought so. :-)

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