Comment on Do straight lines and flat planes exist in nature?
bitwaba@lemmy.world 6 months agoLight travels along geodesics that curve because spacetime itself is curved. Geodesics are curves that minimize distance between two points in a curved space. They are considered straight lines in a curved space, but it’s right there in the definition. Geodesics are curves. Our reality is a curved space, therefore straight lines in our curved space are curves. They are not straight.
Our reality is not matiematically flat. It is matiematically curved.
Blue_Morpho@lemmy.world 6 months ago
From the point of view of light, it is traveling in a straight line. It does not observe the curve therefore spacetime isn’t curved to it. There is no preferred reference frame.
It is the same with special relativity. If a particle is moving at near light speed, you observe it as heavier. But from the particle’s point of view it is you who are moving and you are heavier.
Curved spacetime is a mathematical transformation to reconcile the different reference frames in the same way time dilation is a transform between reference frames.
There is no absolute frame of reference.
bitwaba@lemmy.world 6 months ago
You’re not taking about the same thing as everyone else.
You’re comparing reality to reality, curvature to curvature. We’re talking mathematical theory. There’s nothing about our reality of spacetime that meets the definition of mathematically flat.
Type however many paragraphs you want about reference frames. None of them adhere to being mathematically flat. They are all curved spacetime.
Blue_Morpho@lemmy.world 6 months ago
There is no absolute frame of reference!
Light travels mathematically straight in one frame of reference but curved in another. Both are correct. You use mathematical transforms to map one coordinate system onto another in the same way you can map a mathematical straight line into curved geometry.
www.einstein-online.info/en/…/equivalence_light/
Look at the example they gave of light in an accelerating elevator (which is actually an example from Einstein book on relativity). One has straight light and the other is curved. Both reference frames are correct.
bitwaba@lemmy.world 6 months ago
There’s no absolute frame refrence in physics. We’re talking math theory here.
Light in an accelerating elevator is physics. Light in an anything is physics.
xkcd.com/435/