I Do we know how many meters long one second is?

  • I
  • Thread starter Thread starter student34
  • Start date Start date
student34
Messages
639
Reaction score
21
TL;DR Summary
Do we know how many meters long one second is?
In other words, how many meters long is the world line of a particle at rest for 1 second?
 
Physics news on Phys.org
student34 said:
Summary:: Do we know how many meters long one second is?

In other words, how many meters long is the world line of a particle at rest for 1 second?
The conversion factor from time to length is the speed of light. For an object at rest in some IRF for proper/coordinate time ##t##, the worldline has length ##ct##.

If ##t = 1s##, then the length of the worldline is approximately ##3 \times 10^{8} \ m##.
 
Possibly illuminating:
 
I guess this means that we pass through time at the speed of light. Interesting.
 
Reply
  • Skeptical
Likes weirdoguy and PeroK
student34 said:
I guess this means that we pass through time at the speed of light.
While there is a sense in which this is true, it is a very limited sense and you can't really draw any useful inferences from it. We have had a number of previous PF threads dealing with the confusion caused by taking this statement too far.
 
Reply
  • Like
  • Informative
Likes PeroK and Keith_McClary

Thread 'Euclidean geometry and gravity'

I asked a question here, probably over 15 years ago on entanglement and I appreciated the thoughtful answers I received back then. The intervening years haven't made me any more knowledgeable in physics, so forgive my naïveté ! If a have a piece of paper in an area of high gravity, lets say near a black hole, and I draw a triangle on this paper and 'measure' the angles of the triangle, will they add to 180 degrees? How about if I'm looking at this paper outside of the (reasonable)...
View full post »

Thread 'Jackson: justification of the Poynting vector by GR'

The Poynting vector is a definition, that is supposed to represent the energy flow at each point. Unfortunately, the only observable effect caused by the Poynting vector is through the energy variation in a volume subject to an energy flux through its surface, that is, the Poynting theorem. As a curl could be added to the Poynting vector without changing the Poynting theorem, it can not be decided by EM only that this should be the actual flow of energy at each point. Feynman, commenting...
View full post »

Similar threads

I How many meter sticks are there in this length contraction reasoning?
Replies
12
Views
2K
B Calculating Time taken to reach speed with Time Dilation
Replies
18
Views
1K
I How fast does the particle go through spacetime?
Replies
20
Views
2K
B Meaningfulness of the speed of light
Replies
25
Views
2K
I Arguments leading to the speed of light as a dimensionless constant
2
Replies
64
Views
4K
B "Spacetime Physics" by Taylor and Wheeler
Replies
32
Views
5K
I Spacetime expansion - time dimension expansion
Replies
48
Views
3K
I Black Hole: Knock on the horizon
Replies
34
Views
2K
A When and Why Was the Definition of the Meter Changed?
3
Replies
101
Views
11K
I Is the concept of a one-way speed of light meaningful and measurable?
Replies
25
Views
4K

Hot Threads

Recent Insights

Back
Top