GR explanation of Newtonian Phenomena

aachenmann
Messages
11
Reaction score
0
1. How would a general relativist explain why an object falls towards the earth?

2. Is it correct to say that it is not the apple that falls towards the Earth but it is the Earth that accelerates towards the apple? Why is this ok to say?
 
Physics news on Phys.org
The apple follows a geodesic path through space-time. One way o describing the mathematical characteristics of this path is to say that it satisfies the principle of extremal aging.

see for instance http://www.bun.kyoto-u.ac.jp/~suchii/extrem.aging.html
http://www.eftaylor.com/pub/chapter2.pdf

and look for past PF posts with this keyword.

2) The question is really irrelevant in GR - it doesn't matter which viewpoint you use.
 
Last edited by a moderator:
aachenmann said:
1. How would a general relativist explain why an object falls towards the earth?
Science does not explain, it describes. To say that it explains leads one into a logical circle.
2. Is it correct to say that it is not the apple that falls towards the Earth but it is the Earth that accelerates towards the apple? Why is this ok to say?
What accelerates is actually doing the acceleration is a coordinate dependant statement. Once you choose a coordinate system you can state whose coordinates in that system represents an accelerating object. Here I speak of 3-acceleration since the 4-acceleration of each object, i.e. Earth and apple, is zero.

Pete
 
Since the OP is no longer with us, there seems no point in keeping this thread open.
 
Thread 'Can this experiment break Lorentz symmetry?'
1. The Big Idea: According to Einstein’s relativity, all motion is relative. You can’t tell if you’re moving at a constant velocity without looking outside. But what if there is a universal “rest frame” (like the old idea of the “ether”)? This experiment tries to find out by looking for tiny, directional differences in how objects move inside a sealed box. 2. How It Works: The Two-Stage Process Imagine a perfectly isolated spacecraft (our lab) moving through space at some unknown speed V...
Does the speed of light change in a gravitational field depending on whether the direction of travel is parallel to the field, or perpendicular to the field? And is it the same in both directions at each orientation? This question could be answered experimentally to some degree of accuracy. Experiment design: Place two identical clocks A and B on the circumference of a wheel at opposite ends of the diameter of length L. The wheel is positioned upright, i.e., perpendicular to the ground...
According to the General Theory of Relativity, time does not pass on a black hole, which means that processes they don't work either. As the object becomes heavier, the speed of matter falling on it for an observer on Earth will first increase, and then slow down, due to the effect of time dilation. And then it will stop altogether. As a result, we will not get a black hole, since the critical mass will not be reached. Although the object will continue to attract matter, it will not be a...
Back
Top