Speed of photons and its effect on us

  • Context: High School 
  • Thread starter Thread starter giananimohit
  • Start date Start date
  • Tags Tags
    Photons Speed
Click For Summary

Discussion Overview

The discussion revolves around the nature of photons and their behavior at the speed of light, particularly focusing on the implications for perception and the concept of time. Participants explore theoretical aspects, including Lorentz transformations and the idea of rest frames, as well as the challenges in reconciling the properties of light with classical physics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that if photons travel at the speed of light, then time for them stops relative to an observer, leading to confusion about whether photons are stationary.
  • Others argue that it is incorrect to apply Lorentz transformations to photons, as they do not have a rest frame, and thus the notion of time stopping for them is not valid.
  • A participant expresses difficulty in understanding why classical laws, such as Lorentz transformations, cannot be applied to light, highlighting a gap in their comprehension of the topic.
  • One participant provides a spacetime diagram to illustrate how proper time changes with speed and emphasizes that proper time does not apply to photons.
  • Another participant points out the contradiction between the concepts of "traveling at the speed of light" and "stationary," indicating that these terms cannot coexist in the context of photons.
  • Some participants mention that while Maxwell's equations apply to light, there are limitations to how other physical laws can be interpreted at light speed.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and confusion regarding the nature of photons and the application of physical laws. There is no consensus on the implications of photons being at the speed of light, and multiple competing views remain regarding the interpretation of time and motion in relation to light.

Contextual Notes

Participants acknowledge limitations in their understanding of advanced concepts such as Lorentz transformations and the implications of massless particles, which may affect their interpretations and conclusions.

giananimohit
Messages
3
Reaction score
0
If something is traveling at the speed of light, its time stops to a relative outsider.
But photons (basically light) are traveling at the speed of light... So does that mean that to me the photons are stationary? But if they are stationary, then they're not being reflected off an object and coming to my eyes. So then how do we see?

Also, it's my first post here. So if I didn't do something right, let me know.
And I'm definitely not as knowledgeable as you guys, so use "baby words" please?
 
Physics news on Phys.org
Hi mohit. You can't apply the Lorentz transformations from an observer's frame to that of a photon because a photon has no rest frame. The Lorentz transformations take you from one rest frame to another so it makes no sense to apply it to a photon. As such the result that "time stops for a photon relative to an observer" is not really valid.
 
giananimohit said:
If something is traveling at the speed of light, its time stops to a relative outsider.
But photons (basically light) are traveling at the speed of light... So does that mean that to me the photons are stationary? But if they are stationary, then they're not being reflected off an object and coming to my eyes. So then how do we see?

Also, it's my first post here. So if I didn't do something right, let me know.
And I'm definitely not as knowledgeable as you guys, so use "baby words" please?
It is hard to reconcile 'stationary' and 'travelling at the speed of light'. So you must choose one of these and as you say, experience shows that light is not stationary.

Of course, by definition, everything that has mass can be said to be stationary in some frame, but this is not true of massless stuff like light.
 
Hm. I think I might be more confused than I was before I asked this question.
Thanks for your answers though! I'll read up on Lorentz transformations.
 
Well, your original question was "But photons (basically light) are traveling at the speed of light... So does that mean that to me the photons are stationary?"
Do you not see that "traveling at the speed of light" and "stationary" are contradictory?
 
HallsofIvy said:
Well, your original question was "But photons (basically light) are traveling at the speed of light... So does that mean that to me the photons are stationary?"
Do you not see that "traveling at the speed of light" and "stationary" are contradictory?

That's exactly why I was confused. I know they're contradictory but I didn't know why. I was unaware of Lorentz transformations and how you can't compare things with different frames of motion.
Also I can't wrap my brain around why so many laws can't be applied to light. I know all of physics pretty much breaks down when traveling at those speeds but it's still hard for me to imagine why.
 
giananimohit said:
I was unaware of Lorentz transformations and how you can't compare things with different frames of motion.
No one said this. The Lorentz transformations can always be applied to boost from the rest frame of an inertial observer to that of another inertial observer. They can't be used to boost from the rest frame of an inertial observer to that of light because it makes no sense to define an inertial rest frame for light.
 
giananimohit said:
If something is traveling at the speed of light, its time stops to a relative outsider.
But photons (basically light) are traveling at the speed of light... So does that mean that to me the photons are stationary?
I'm not going to address all your points, some of them have already been addressed by others. I just want to show you how the Proper Time of an object traveling at some speed relative to you changes with speed and why we can't talk about the Proper Time for a photon. To do this, I have made a spacetime diagram showing you in blue and a bunch of green objects traveling away from you at different speeds, every 10% of the speed of light up to the last red object which is traveling at 99.9% of the speed of light. The speed of light in this diagram is one foot per nsec. I have drawn in a black line at the Coordinate Time of 10 nsecs so that you can easily see how far each object has traveled in that amount of time. You can see that they each travel 1 foot farther than the previous one.

The dots on each line show one nsec increments of Proper Time and I have shown ten increments for you (in blue) and for all the green objects but for the last one in red I have shown only one increment because if I had shown ten, the diagram would be ten times larger. If I had shown an object traveling at 99.99%c it would have had its first increment of Proper Time at 70 nsec and 70 feet. At 99.999%c these numbers would be over 223 and at 99.9999%c they would be over 707. As the speed of an object approaches that of light, the first increment approaches infinity so we don't want to make a drawing of an object traveling too close to it.

I have shown a photon as the thin red line extending out from the red object. Proper Time does not apply to it.

attachment.php?attachmentid=59332&stc=1&d=1370527545.png


Any questions?
 

Attachments

  • TenSpeeds.PNG
    TenSpeeds.PNG
    24 KB · Views: 1,418
  • #10
giananimohit said:
Also I can't wrap my brain around why so many laws can't be applied to light.
Classically speaking Maxwells equations apply to light. I am not sure what other laws you think should apply.
 
  • #11
giananimohit said:
If something is traveling at the speed of light, its time stops to a relative outsider.
But photons (basically light) are traveling at the speed of light... So does that mean that to me the photons are stationary?
No, time in a moving objects frame of reference has nothing to do with how we see it moving. It has no effect upon us. If ball bouncing vertically were to pass you, horizontally, at near the speed of light, you would see it going up and down very slowly by that would not afffect how fast it was passing.

But if they are stationary, then they're not being reflected off an object and coming to my eyes. So then how do we see?

Also, it's my first post here. So if I didn't do something right, let me know.
And I'm definitely not as knowledgeable as you guys, so use "baby words" please?
 

Similar threads

High School Let me ask a thing about the Speed of Light
  • · Replies 6 ·
Replies
6
Views
2K
High School Why Do Events Freeze For Me at the Speed of Light?
  • · Replies 4 ·
Replies
4
Views
1K
Undergrad A question about the speed of light and electromagnetism
  • · Replies 51 ·
2
Replies
51
Views
5K
High School Energy loss of a photon
  • · Replies 1 ·
Replies
1
Views
1K
High School Do photons travel instantaneously?
  • · Replies 41 ·
2
Replies
41
Views
6K
High School Time and Space Distortions of Photons: What Am I Misunderstanding?
  • · Replies 6 ·
Replies
6
Views
2K
High School Kugelblitz at the speed of light misconception
  • · Replies 10 ·
Replies
10
Views
3K
High School Experience Travel on a Photon: Hitch-Hiker's Guide to the Universe
  • · Replies 7 ·
Replies
7
Views
2K
High School Why Does the Speed of Light Max Out at 186,282 Miles Per Second?
  • · Replies 120 ·
5
Replies
120
Views
9K
High School Thought Experiment: Behavior of shadow of object moving at speed c
  • · Replies 14 ·
Replies
14
Views
2K