If you were out in space, motionless

  • Context: Undergrad 
  • Thread starter Thread starter taybot
  • Start date Start date
  • Tags Tags
    Space
Click For Summary

Discussion Overview

The discussion revolves around the concept of time dilation in the context of being motionless in space. Participants explore how time is perceived when not influenced by gravity or motion, questioning whether a watch would tick faster in such a scenario.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that if one were motionless in space, their watch would tick faster due to not traveling through space.
  • Others argue that being motionless is relative and that one cannot be truly motionless with respect to all reference frames, which complicates the question of time perception.
  • A participant references a formula for time dilation, indicating that the rate of a watch's proper time relative to coordinate time is influenced by velocity, achieving a maximum when at rest.
  • There is uncertainty about how much faster a watch would tick when motionless in space, with some participants expressing confusion about the formula and its implications.
  • One participant mentions that while they may be falling in a vacuum, they would still be considered almost motionless, raising further questions about the effect on time measurement.
  • Another participant clarifies that the rate of a clock appears to change relative to other moving clocks or clocks in different gravitational fields, rather than the clock itself ticking faster or slower in absolute terms.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether a watch would tick faster when motionless in space, with multiple competing views and uncertainties remaining about the implications of motion and reference frames.

Contextual Notes

Limitations include the dependence on definitions of motionlessness, the complexity of reference frames, and unresolved mathematical interpretations of time dilation.

taybot
Messages
26
Reaction score
0
If you were in a spaceship going the speed of light you wouldn't travel through time because you would be traveling through space instead. I got that.

So if you were to sit out in space completely free from gravity, motionless, and you were wearing a watch, does that mean time would go faster?

Since you aren't traveling through space at all, wouldn't that mean you are traveling through time at light speed and wouldn't that mean your watch would go faster?
 
Physics news on Phys.org
taybot said:
If you were in a spaceship going the speed of light you wouldn't travel through time because you would be traveling through space instead.
No, you wouldn't be going the speed of light because you have mass.

taybot said:
So if you were to sit out in space completely free from gravity, motionless, and you were wearing a watch, does that mean time would go faster?

Since you aren't traveling through space at all, wouldn't that mean you are traveling through time at light speed and wouldn't that mean your watch would go faster?
In in any inertial frame the rate of any watch's proper time wrt coordinate time would be given by:
[tex]\frac{d\tau}{dt}=\frac{1}{\gamma}=\sqrt{1-\frac{v^2}{c^2}}[/tex]

This expression indeed achieves a maximum of 1 for v=0.
 
not sure what that formula means but since you wrote indeed, I take it that the watch will tick faster if you are out in space, motionless...

So how much faster? I figure it wouldn't be that much faster than normal time that passes for us, right?

Because already if you are sitting somewhere, you're accelerating through space, just not accelerating that much I figure, so probably your watch wouldn't tick that much faster if you were out in space, motionless.

Is that right?
 
taybot said:
not sure what that formula means ...

So how much faster?
Sorry, I don't know I can answer you in a satisfactory manner then. The answer to "how much faster" is given by the formula.
 
not sure what that formula means but since you wrote indeed, I take it that the watch will tick faster if you are out in space, motionless...
What do you mean by motionless ? I think you are failing to take into account that phenomena like clocks slowing refer to observations from different frames of reference. You would not notice anything as long as your motion is uniform ( unaccelerated).

But someone traveling at uniform velocity relative to you would notice your clock apparently slowing.
 
You can never be motionless with respect to every reference frame. In some reference frame you are motionless, and in others you are moving. I don't think your question can obtain a satisfactory answer because one of your assumptions is wrong.
 
I read this book, The Fabric of the Cosmos and he says you can be motionless if you jump into a shaft that has air removed from it.

Even if you can't be motionless, you would be falling, pretty much motionless. Closer to motionless than when you are sitting in front of your computer, because if you're doing that, you're accelerating.

Anyways, let's say you jump into that airless shaft and you are falling, motionless, or almost motionless. And if you're wearing a watch, would it tick faster, or wouldn't it?Edit:

I looked at Dale's answer again and he says:

"The answer to "how much faster" is given by the formula."

So at least I know your watch would indeed tick faster. I was just wondering if it would tick twice as fast, or less. I don't know how to do that equation. Thanks!
 
DaleSpam said:
In in any inertial frame the rate of any watch's proper time wrt coordinate time would be given by:
[tex]\frac{d\tau}{dt}=\frac{1}{\gamma}=\sqrt{1-\frac{v^2}{c^2}}[/tex]

This expression indeed achieves a maximum of 1 for v=0.

taybot said:
... I looked at Dale's answer again and he says:

"The answer to "how much faster" is given by the formula."

So at least I know your watch would indeed tick faster. I was just wondering if it would tick twice as fast, or less. I don't know how to do that equation. Thanks!

The watch on your wrist always appears to tick at the same rate whether you are motionless far out in space or on the surface of a neutron star or in a rocket traveling at 0.999c relative to the Earth. It is the rate of other clocks moving relative to you or located at different heights in a gravitational field that appear to be running faster or slower than your own watch.

Using the equation given by Dale, the rate of a clock moving at at 0.866c relative to you is:

[tex]\frac{d\tau}{dt}=\frac{1}{\gamma}=\sqrt{1-\frac{v^2}{c^2}} = \sqrt{1-0.866^2} \approx 1/2[/tex]

In other words the clock moving at 0.866c relative to you appears to be ticking twice as slow as your watch, but this factor of 2 only happens at this precise velocity relative to you. If the other clock was moving at 0.99498c relative to you, then the other clock would appear to be running 10 times slower than your own watch because:

[tex]\frac{d\tau}{dt}=\frac{1}{\gamma}=\sqrt{1-\frac{v^2}{c^2}} = \sqrt{1-0.99498^2} \approx 1/10[/tex]
 

Similar threads

  • · Replies 25 ·
Replies
25
Views
3K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 11 ·
Replies
11
Views
1K
  • · Replies 12 ·
Replies
12
Views
4K
  • · Replies 9 ·
Replies
9
Views
1K
  • · Replies 98 ·
4
Replies
98
Views
9K
  • · Replies 150 ·
6
Replies
150
Views
5K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K