What happens to time when gravity is absent

  • Context: Graduate 
  • Thread starter Thread starter quantify
  • Start date Start date
  • Tags Tags
    Gravity Time
Click For Summary

Discussion Overview

The discussion revolves around the nature of time in the absence of gravity, exploring concepts from both general and special relativity, as well as philosophical implications related to the mind-body problem. Participants examine how time is perceived relative to gravitational fields and question whether time can exist independently of gravity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Philosophical

Main Points Raised

  • Some participants suggest that time is always relative to gravity, questioning if time ceases to exist without it.
  • Others argue that special relativity describes time/space without gravity, prompting inquiries about the nature of time in that context.
  • A participant raises the question of whether time stops at the center of the Earth, referencing Newton's laws and gravitational pull.
  • There is a discussion about gravitational time dilation, with some asserting that clocks in stronger gravitational fields tick more slowly than those in weaker fields.
  • Some participants challenge the idea that time and space can only be defined in relation to gravity, questioning the existence of time without mass and gravitational influence.
  • A philosophical angle is introduced regarding the mind-body problem, questioning how the mind, which lacks mass, fits into the framework of relativity.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between time and gravity, with no consensus reached on whether time can exist independently of gravitational influence. The discussion includes both technical and philosophical perspectives, highlighting ongoing debates in the field.

Contextual Notes

Some claims about gravitational effects and time dilation are not fully resolved, and there are various assumptions about the definitions of time and space that remain unaddressed.

quantify
Messages
4
Reaction score
0
If it has been determined that time/space is always relative to gravity as observed in several equations (correct me if I'm wrong), then does time cease to exist if viewed from a relative plane perspective that lacks any form of gravity? Could a relative plane perspective even exist without being relative to a mass that observes gravity?

edit: and say you can never have rule out gravity, can a comparable state be formed by having to gravitational fields directly and perfectly counter act each other creating some sort of equilibrium?
 
Last edited:
Physics news on Phys.org
Special Relativity is space/time without gravity(curvature).
 
so i guess my question would be what is time in relation to special relativity

edit: According to Newton when you enter into the exact center of Earth you observe an equal gravitation pull on all sides, so does time stop there?
 
Last edited:
quantify said:
so i guess my question would be what is time in relation to special relativity

edit: According to Newton when you enter into the exact center of Earth you observe an equal gravitation pull on all sides, so does time stop there?

The force of gravity at the centre of the Earth (or anywhere inside the hollow of a sphere with a solid shell) is zero. Gravitational time dilation is determined by gravitational potential, sqrt(GM/R) and the potential does not go to zero at the centre of the Earth. As an object goes towards the centre of the Earth its gravitational potential is always increasing, reaching a maximum at the centre of the Earth.
 
quantify said:
so i guess my question would be what is time in relation to special relativity

edit: According to Newton when you enter into the exact center of Earth you observe an equal gravitation pull on all sides, so does time stop there?

As kev points out, the gravitational potential increases. GR predicts that the clock rate will decrease with respect to the surface. The clocks will not stop, their rate will decrease by a very small amount. See also here: http://en.wikipedia.org/wiki/Pound-Rebka_falling_photon_experiment
 
quantify said:
If it has been determined that time/space is always relative to gravity as observed in several equations (correct me if I'm wrong)
I think you're wrong, I've never heard general relativity described in this way.
 
quantify said:
If it has been determined that time/space is always relative to gravity as observed in several equations (correct me if I'm wrong), then does time cease to exist if viewed from a relative plane perspective that lacks any form of gravity? Could a relative plane perspective even exist without being relative to a mass that observes gravity?

edit: and say you can never have rule out gravity, can a comparable state be formed by having to gravitational fields directly and perfectly counter act each other creating some sort of equilibrium?

JesseM said:
I think you're wrong, I've never heard general relativity described in this way.

It is true that, in general relativity, if two clocks are at rest relative to one another but one is in a stronger gravitational field, it will tick more slowly than the one in the weaker gravitational field. I presume that was what was meant.
 
HallsofIvy said:
It is true that, in general relativity, if two clocks are at rest relative to one another but one is in a stronger gravitational field, it will tick more slowly than the one in the weaker gravitational field. I presume that was what was meant.
I initially took "time/space is always relative to gravity" to mean something more--that in some sense they can't even be defined except in relation to gravity--but you may be right.
 
How can you define space-time without gravity? Isn't every clock embedded in mass, And so too the observers?
 
  • #10
All clocks and observers are contained within the gravitational affect of all matter in the universe - Mach and many modern theorists claim this defines the magnitude of the inertial reaction force (commonly condensed to F = ma). But since the G field is isotropic, we don't have a good way of investigating its local influence upon mass - specifically no one has yet related the magnitude of Newton's reaction to distant matter in a way that does not at some point require some ad hoc physics. You might take a look at Garth's paper "SCC" if you have an interest in seeing how difficult it is to arrive at plausible syllogism
 
  • #11
So I just signed up to post on this topic, and I'm sorry to swing it into a philosophical direction, but this seems the best way to make the question feasible.

In reference to the mind-body problem, Descartes proposed that the mind exists in time and not in space. The mind has no mass and no gravitational force is being exerted on it - so does this even make sense with reference to relativity?
 
  • #12
morphine said:
So I just signed up to post on this topic, and I'm sorry to swing it into a philosophical direction, but this seems the best way to make the question feasible.

In reference to the mind-body problem, Descartes proposed that the mind exists in time and not in space. The mind has no mass and no gravitational force is being exerted on it - so does this even make sense with reference to relativity?

There is no evidence for the mind existing as something independent of the brain. Descartes didn't have the knowledge of human physiology that we have now.
 

Similar threads

  • · Replies 35 ·
2
Replies
35
Views
5K
  • · Replies 9 ·
Replies
9
Views
936
  • · Replies 37 ·
2
Replies
37
Views
6K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 38 ·
2
Replies
38
Views
5K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
6
Views
3K
  • · Replies 23 ·
Replies
23
Views
3K
  • · Replies 21 ·
Replies
21
Views
5K