Speed of light? Or velocity of free space?

Click For Summary

Discussion Overview

The discussion revolves around the nature of light's speed, particularly questioning why it is referred to as the "speed of light" when it may vary in different environments, such as a vacuum versus a medium. Participants explore concepts related to the interaction of light with space and matter, and the implications of these interactions on the understanding of light's velocity.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants propose that light travels at approximately 186,000 m/s in its "natural" environment but suggest that this speed changes in a vacuum, raising questions about the terminology used to describe it.
  • Others argue that space is effectively a vacuum and that light's speed remains constant, with variations in speed attributed to interactions with matter rather than changes in the properties of space itself.
  • A participant suggests that the unique properties of space may influence light's characteristics, implying that space could be composed of some substance that affects light's propagation.
  • There is a philosophical assertion that theories are never complete and that constants are subject to change, reflecting a broader view on scientific understanding.
  • Another participant emphasizes that while light may experience delays when interacting with atoms, the speed of light in a vacuum remains constant at 186,000 m/s, suggesting a distinction between speed in a vacuum and speed in a medium.

Areas of Agreement / Disagreement

Participants express differing views on whether light's speed is fundamentally altered by its environment or remains constant, leading to an unresolved debate on the nature of light's velocity and the implications of space's properties.

Contextual Notes

Participants reference the interaction of light with matter and the concept of propagation delays, but the discussion does not resolve the underlying assumptions about the nature of space or the definitions of speed and velocity in this context.

dgoodpasture2005
Messages
199
Reaction score
0
Light travels at approximately 186,000 m/s. as long as it is in its "natural" environment(space)... but put it in a vacuum and things change. So tell me then... Why do we call it the speed of light still? How about the velocity of space. So now... let's discuss this... please do not lock this thread, it is completely feasible.. and is not coming from a speculative pedestrian.. so i think it fits inside the S&D forum guidelines.
 
Last edited:
Astronomy news on Phys.org
dgoodpasture2005 said:
Light travels at approximately 186,000 m/s. as long as it is in its "natural" environment(space)... but put it in a vacuum and things change.


How so? Space is a vacuum, or at least the closest thing we have to a vacuum. Even when light is interacting with matter it still travles at the same velocity. We only say the speed is different because the atoms absorb then re-emmit the photons causing a delay in the propigation.

Unless you can prove that the vacuum of space is made of some kind of "substance" I don't see how we can give it a velocity. What it the velocity of nothing?
 
Yes, this is my point... when placed in an artificial vacuum light acts/interacts and travels at different speeds... let light flow in space and it flows back at 186,000 m/s. Space must be made of some substance.(energy/atoms/molecules, make up) Can you prove it's not? "...the velocity of nothing?" this is what I'm trying to get at. Right now it's nothing.. unfortunately i cannot blast off into space and do experiments.. I'd much like that :) The way light acts and loses its characteristics when placed in a vacuum(or taken out of space) would lead one to believe that, yes... space has a unique make up that gives light its unique properties in that environment. It's not light that is allowing light to travel at 186,000 m/s, it's space.
 
Last edited:
Theories are never complete, laws are made to be broken, the only thing that never changes is a constant, and the only thing constant is change.
 
The speed of light in vacuum is ~186,000 mps. If a photon encounters something in space such as a hydrogen atom, it is absorbed, or absorbed and re-emitted. In the case that it is re-emitted, a propagation delay results but the speed in between atoms is still the 186,000... So in reality the speed of light is always the same.

Again, if you have science questions then please post to a regular physics forum. If you wish to post a theory, then please review the independent research posting guidelines.
https://www.physicsforums.com/showthread.php?t=82301
 
Last edited:

Similar threads

High School What Medium Does Light Travel Through in Space?
  • · Replies 3 ·
Replies
3
Views
2K
High School Does Gravitational Time Dilation Affect the Speed of Light in Outer Space?
  • · Replies 32 ·
2
Replies
32
Views
4K
High School Did anyone actually see the space moving faster than light?
  • · Replies 24 ·
Replies
24
Views
4K
High School Speed of Light in Free Space - Einstein's Second Principle
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad Why measure the speed of light in one direction?
  • · Replies 7 ·
Replies
7
Views
1K
High School How Can We Prove That Space is Expanding?
  • · Replies 25 ·
Replies
25
Views
3K
Undergrad Perceived Speed of Objects in Space
  • · Replies 5 ·
Replies
5
Views
2K
High School Traveling through space at zero km/s
  • · Replies 11 ·
Replies
11
Views
1K
High School What If We Could See the Past by Placing a Mirror on the Sun?
  • · Replies 13 ·
Replies
13
Views
3K
High School One-Way Speed of Light
  • · Replies 93 ·
4
Replies
93
Views
6K