Can the speed of light be constant and absolute?

In summary, light behaves as both a wave and a particle. This is based on the assumption that it has mass, and the effects of heat and vacuum environments. Without going into more detail, it is unclear what you are looking for.
  • #1
Matthew Bristow
12
0
Hi all
I have struggled with the assumptions that the speed of light is absolute and constant. I have some logic to this which is based on the common assumptions that light behaves both as a wave and a particle. It is also based on light having mass, the effects of heat and vacuum environments. Without going into details, does anyone have views on this or study it?

Cheers
Matt
 
Science news on Phys.org
  • #2
Matthew Bristow said:
Hi all
I have struggled with the assumptions that the speed of light is absolute and constant. I have some logic to this which is based on the common assumptions that light behaves both as a wave and a particle. It is also based on light having mass, the effects of heat and vacuum environments. Without going into details, does anyone have views on this or study it?
Welcome to PF!

Constant and the same for all observers is a subset of absolute, isn't it?

In any case, I'm sorry but basically everything else you said about light is wrong. Please start by reading this and let us know if there are things you still need cleared up:

https://en.m.wikipedia.org/wiki/Special_relativity
 
  • Like
Likes BvU
  • #3
russ_watters said:
Welcome to PF!

Constant and the same for all observers is a subset of absolute, isn't it?

In any case, I'm sorry but basically everything else you said about light is wrong. Please start by reading this and let us know if there are things you still need cleared up:

https://en.m.wikipedia.org/wiki/Special_relativity

Thanks Russ. Will do.
 
  • #4
It's not clear what you're looking for. Are you asking for papers or articles giving the theoretical foundation supporting the invariant nature of the speed of light? If so, I recommend Einstein's original paper on special relativity:
https://einsteinpapers.press.princeton.edu/vol2-trans/154
 
  • #5
russ_watters said:
Welcome to PF!

Constant and the same for all observers is a subset of absolute, isn't it?

In any case, I'm sorry but basically everything else you said about light is wrong. Please start by reading this and let us know if there are things you still need cleared up:

https://en.m.wikipedia.org/wiki/Special_relativity
Hi Russ
Thanks for the link and direct feedback. I should have posted the comment as a question, not statement so I understand why you said it was wrong.

I have read through the link you sent and it does make me ask more questions. One in particular is that if space-time cannot tolerate or prohibits motion faster than the speed of light (c) then c squared cannot be achieved, making e=mc2 a false formula?
 
  • #6
Matthew Bristow said:
I have read through the link you sent and it does make me ask more questions. One in particular is that if space-time cannot tolerate or prohibits motion faster than the speed of light (c) then c squared cannot be achieved, making e=mc2 a false formula?
C2 has units of m2/s2. It isn't a speed. It really isn't anything except most of the units for energy. Completed, it is kg-m2/s2, or just J (Joules); the unit for energy. This should look similar to you to the equation for Newtonian kinetic energy, which also contains speed squared.

This is a common misunderstanding, caused by not recognizing how integral the units are to the equations. They aren't just doing math to numbers. Indeed, it is often useful to use the units without numbers!
 
  • #7
russ_watters said:
C2 has units of m2/s2. It isn't a speed. It really isn't anything except most of the units for energy. Completed, it is kg-m2/s2, or just J (Joules); the unit for energy. This should look similar to you to the equation for Newtonian kinetic energy, which also contains speed squared.

This is a common misunderstanding, caused by not recognizing how integral the units are to the equations. They aren't just doing math to numbers. Indeed, it is often useful to use the units without numbers!
Got it thanks.

To ask a question in my most logical way and why I joined this forum...if it is pure supposition and wrong, let me know. Likewise if it is an interesting question for a layperson.

I was speculating in my layperson mind that: if it is true that light behaves / has properties of both waves and particles (is this wrong?)
Then
Particles behave differently under both extreme pressure and heat.
If
We look at a macro level, pressure and heat exist to extremes is black holes and supernovas respectively.
So
Particle light behaviour should be different and it's speed should be faster.
Then
Our assumptions about celestial bodies being x million light years away is false and they are in fact closer.

To tell me these factors have been considered could be naive because "postulates" that support current thinking have not been proven in these conditions.
 
  • #8
russ_watters said:
C2 has units of m2/s2. It isn't a speed. It really isn't anything except most of the units for energy. Completed, it is kg-m2/s2, or just J (Joules); the unit for energy. This should look similar to you to the equation for Newtonian kinetic energy, which also contains speed squared.

This is a common misunderstanding, caused by not recognizing how integral the units are to the equations. They aren't just doing math to numbers. Indeed, it is often useful to use the units without numbers!
Thanks. So it's an acceleration formula not velocity.
 
  • #9
Matthew Bristow said:
Got it thanks.

To ask a question in my most logical way and why I joined this forum...if it is pure supposition and wrong, let me know. Likewise if it is an interesting question for a layperson.

I was speculating in my layperson mind that: if it is true that light behaves / has properties of both waves and particles (is this wrong?)
Then
Particles behave differently under both extreme pressure and heat.
I would usually answer this question "yes", which could get me in trouble with the physicists here (I'm an engineer) and in this case would lead you down this wrong path you are on. Simply put, just because light has some behaviors in common with particles (or waves), doesn't mean it has all the behaviors in common with particles (or waves). At this point, to avoid the confusion over what it does and doesn't have in common with particles and waves, physicists would say light is neither [classical] particles or waves, but a separate type of entity that has its own specific set of properties/behaviors.

Fluid pressure is not one of those properties/behaviors.
To tell me these factors have been considered could be naive because "postulates" that support current thinking have not been proven in these conditions.
While it's true that there are some limitations to our knowledge/understanding, I'd caution you to not speculate on where those limitations are. You're basically suggesting that thousands of PhD physicists who individually have spent tens of thousands of hours studying the behavior of light haven't thought this through as far as you have. You may get some gruff responsese to that suggestion...
 
  • #10
Matthew Bristow said:
Thanks. So it's an acceleration formula not velocity.
No, acceleration is m/s2. As I said, C2 is most of a forumula for energy.
 
  • #11
russ_watters said:
I would usually answer this question "yes", which could get me in trouble with the physicists here (I'm an engineer) and in this case would lead you down this wrong path you are on. Simply put, just because light has some behaviors in common with particles (or waves), doesn't mean it has all the behaviors in common with particles (or waves). At this point, to avoid the confusion over what it does and doesn't have in common with particles and waves, physicists would say light is neither [classical] particles or waves, but a separate type of entity that has its own specific set of properties/behaviors.

Pressure is not one of those properties/behaviors.

While it's true that there are some limitations to our knowledge/understanding, I'd caution you to not speculate on where those limitations are. You're basically suggesting that thousands of PhD physicists who individually have spent tens of thousands of hours studying the behavior of light haven't thought this through as far as you have. You may get some gruff responsese to that suggestion...
Thanks Russ
I am a middle aged person who enjoyede matriculation physics only. These types of questions have stuck with me for a long time and, based on your reply, is a somewhat valid and inquisitive question? By no means do I want to be disrespectful to anyone regarding the postulates comment. Sorry.
 
  • #12
russ_watters said:
No, acceleration is m/s2. As I said, C2 is most of a forumula for energy.
OK but e is the output here (being joules or energy). The two inputs are mass and C...I never memorised formula but rembered them by the story...if you take a mass and accelerate it to the speed of light squared it will give off a huge amount of joules. The key here for me was accelerate it to c2. It will give off joules over the acceleration curve but you will/cannot reach the end velocity of c2...you will respond huge joules even before you get to c1...
 
  • #13
Matthew Bristow said:
Thanks Russ
I am a middle aged person who enjoyede matriculation physics only. These types of questions have stuck with me for a long time and, based on your reply, is a somewhat valid and inquisitive question? By no means do I want to be disrespectful to anyone regarding the postulates comment. Sorry.
Somewhat. But mostly at the starting question. You took the logic pretty far based on the incorrect premise though. You're doing fine, I just don't want you to waste your own time or get in trouble going so far down a closed road, when reading the sign at the intersection could have avoided it.
 
  • #14
Matthew Bristow said:
OK but e is the output here (being joules or energy). The two inputs are mass and C...I never memorised formula but rembered them by the story...if you take a mass and accelerate it to the speed of light squared it will give off a huge amount of joules. The key here for me was accelerate it to c2. It will give off joules over the acceleration curve but you will/cannot reach the end velocity of c2...you will respond huge joules even before you get to c1...
Wowie, that makes no sense... :wink:
 
  • Like
Likes russ_watters and Vanadium 50
  • #15
berkeman said:
Wowie, that makes no sense... :wink:
Really? And your feedback is constructive how?
russ_watters said:
Somewhat. But mostly at the starting question. You took the logic pretty far based on the incorrect premise though. You're doing fine, I just don't want you to waste your own time or get in trouble going so far down a closed road, when reading the sign at the intersection could have avoided it.
Thanks. Appreciate the constructive advice. I will keep reading before posting.
 
  • #16
Matthew Bristow said:
OK but e is the output here (being joules or energy). The two inputs are mass and C...I never memorised formula but rembered them by the story...if you take a mass and accelerate it to the speed of light squared it will give off a huge amount of joules. The key here for me was accelerate it to c2. It will give off joules over the acceleration curve but you will/cannot reach the end velocity of c2...you will respond huge joules even before you get to c1...
Well, that's actually not what that equation is for. What it tells you is the energy equivalent of mass; it's what you get when an amount of mass is converted to energy.
https://en.wikipedia.org/wiki/Mass–energy_equivalence

What you are describing is [kind of] the Relativistic Kinetic Energy equation (which the mass/energy equivalence is simplified from). It actually goes to infinity as you approach C.
https://en.wikipedia.org/wiki/Kinetic_energy#Relativistic_kinetic_energy_of_rigid_bodies

And again: the speed is just C. Not C2.
 
  • Like
Likes Matthew Bristow
  • #17
Matthew Bristow said:
Really? And your feedback is constructive how?
Well, I couldn't find one thing correct in it to try to build on, sorry.

For example, this makes no sense no matter how hard I try to figure out what you are trying to say:
Matthew Bristow said:
It will give off joules over the acceleration curve
It seems it would be best for you to spend some time at Wikipedia or Hyperphysics learning some basic stuff. I'll see if I can find some links to recommend...
 
  • #18
berkeman said:
Well, I couldn't find one thing correct in it to try to build on, sorry.

For example, this makes no sense no matter how hard I try to figure out what you are trying to say:

It seems it would be best for you to spend some time at Wikipedia or Hyperphysics learning some basic stuff. I'll see if I can find some links to recommend...
It is fine. Russ actually understood it and has already clarified it for me.
 
  • #19
Yeah, Russ is pretty good at that! :smile:
 
  • #20
Matthew Bristow said:
OK but e is the output here (being joules or energy). The two inputs are mass and C...I never memorised formula but rembered them by the story...if you take a mass and accelerate it to the speed of light squared it will give off a huge amount of joules. The key here for me was accelerate it to c2. It will give off joules over the acceleration curve but you will/cannot reach the end velocity of c2...you will respond huge joules even before you get to c1...

If you choose units where ##c = 1## then ##c## and ##c^2## disappear from the formulas. You then have, for example:

##E = m##

In any case, this is the formula for the energy of a massive particle at rest. Speed doesn't come into it. And it doesn't apply to light, which has no mass and no rest energy.
 
  • #21
Something I see I'm going to need to keep pointing out:
Matthew Bristow said:
The key here for me was accelerate it to c2. It will give off joules over the acceleration curve but you will/cannot reach the end velocity of c2...you will respond huge joules even before you get to c1...
Here's how this conversation keeps going:

Me: I'm driving my car at 60 mph.
You: That's impossible, your car can't go 3,600 mph!
 
  • #22
russ_watters said:
Something I see I'm going to need to keep pointing out:

Here's how this conversation keeps going:

Me: I'm driving my car at 60 mph.
You: That's impossible, your car can't go 3,600 mph!
Thanks Russ. Got it.
 
  • #23
Matthew Bristow said:
Thanks Russ. Got it.
Unless it's Elon musk roadster.
 
  • #24
Matthew Bristow said:
Unless it's Elon musk roadster.
Only with the rocket booster option (not sold in stores).
 
  • #25
russ_watters said:
Only with the rocket booster option (not sold in stores).
Haha. Seriously though, why did a visionary guy who loves the universal environment send a piece of redundant trash up there...
 
  • #26
Matthew Bristow said:
...if you take a mass and accelerate it to the speed of light squared it will give off a huge amount of joules.
The equation ##E = mc^2## has nothing to do with accelerating an object. As already stated, it states the equivalence between the mass of some object at rest and the amount of energy that mass represents.

In any case, it's not physically possible to accelerate an object of any nonzero mass to the speed of light, let alone to the square of this speed. When objects are accelerated to appreciable fractions of the speed of light, their mass increases, which means that an ever larger force is needed to continue accelerating that object.
 
  • #27
Mark44 said:
let alone to the square of this speed
Laymen tend to think that the speed of light is a big number and that squaring it results in a bigger number. It is not so.

Expressed in megaparsecs per second, the speed of light is about 9.7 x 10-15. The square of that speed (in megaparsecs squared per seconds squared) would be some kind of accelerating areal coverage rate at 9.45 x 10-29

Pretty small numbers in those units.
 
  • Like
Likes eudo, Dale, russ_watters and 1 other person
  • #28
Matthew Bristow said:
Haha. Seriously though, why did a visionary guy who loves the universal environment send a piece of redundant trash up there...

because it's a classic and because he could :wink::smile:
 
  • #29
Matthew Bristow said:
..space-time cannot tolerate or prohibits motion faster than the speed of light (c) then c squared cannot be achieved, making e=mc2 a false formula?
c2 is a constant of proportionality.
If you set c equal to one, you still have to include it in the formula because of its associated measurement units (L2/T2).
 
  • #30
Look up some articles on the Lorentz transform. There are some with excellent explanations of the speed of light and relativity and different frames of reference.
 

1. Can the speed of light be constant and absolute?

Yes, according to Einstein's theory of relativity, the speed of light in a vacuum is a universal constant and is not affected by the speed or motion of the observer.

2. How was the constant speed of light discovered?

The constant speed of light was first measured by Danish astronomer Ole Rømer in the late 17th century, who observed the changing speed of light as the Earth moved in its orbit around the Sun.

3. Can anything travel faster than the speed of light?

No, according to the theory of relativity, the speed of light is the maximum speed at which all matter and information in the universe can travel.

4. Is the speed of light affected by gravity?

Yes, the speed of light can be affected by gravity. This was confirmed by the famous experiment conducted by Sir Arthur Eddington in 1919, where he observed the bending of light near a massive object such as the Sun.

5. What are the practical implications of the constant speed of light?

The constant speed of light has many practical implications, including its use in GPS technology and telecommunications. It also plays a crucial role in our understanding of the universe and the laws of physics.

Similar threads

Replies
40
Views
14K
Replies
4
Views
2K
  • Special and General Relativity
Replies
18
Views
1K
Replies
4
Views
2K
Replies
8
Views
1K
Replies
12
Views
916
  • Special and General Relativity
2
Replies
45
Views
3K
  • Special and General Relativity
Replies
13
Views
1K
Replies
12
Views
2K
Replies
9
Views
1K
Back
Top