Thread: An Idea about light and it speed

Hi.
This morning I had an idea about light and how it moves.

So as we know light moves at light speed which is about 299 792 458 m/s.

Watching some documentaries I noticed something. When something moves at light of speed (or any speed), the distance of the moving object, shrinks a little bit.

So the first idea is this :

• What if the light traveling at the speed of light shrinks the distance, lets say from sun(as the light source) to earth, so much that it reaches earth almost(ALMOST) instantly (or atleast faster than 8 minutes) ?

And another idea I had.

• Maybe the light itself somehow creates(or uses) wormholes and skips a lot of space , instead of traveling the whole distance?

So what do you think about this ? Is this totally false or the idea could be good ?

Originally Posted by robis97

Watching some documentaries I noticed something. When something moves at light of speed (or any speed), the distance of the moving object, shrinks a little bit.

I think you need to explain what you mean by this assertion. What "documentaries?" What does "the distance of the moving object shrinks a little bit" mean?

Originally Posted by robis97

What if the light traveling at the speed of light shrinks the distance, lets say from sun(as the light source) to earth, so much that it reaches earth almost(ALMOST) instantly ?

By what mechanism would light shrink spacetime? (Hint: I said spacetime.)

Originally Posted by robis97

Maybe the light itself somehow creates(or uses) wormholes and skips a lot of space , instead of traveling the whole distance?

If light did this, it would create observed gapping and basic stellar Spectroscopy would not work at all. There would be a noticeable curvature to every entrance and exit point.

Originally Posted by robis97

So what do you think about this ? Is this totally false or the idea could be good ?

I think it is good that you're putting a lot of thought into this and are interested in the topic. The idea- could use a lot more education.
While education is essential for understanding the necessity of willingness to learn, interest and desire are the motives.
Stay interested- even if the idea could use some work. (Or a total scrapping... )

Okay I found one video where it mentions this "distance shrinking thing"

https://www.youtube.com/watch?v=tflf05x-WVI

He talks about it around 6:45

Maybe I misunderstood him ?

Or I just wrote the "distance of the moving object"

I meant like this:

For example light is traveling from sun to earth. Imagine that as a road. And while it is traveling on that road(concerning to the video I posted) the road shrinks and so the light can move to the destination faster.


EDIT: Here I found something interesting.
http://www.webring.org/l/rd?ring=toe...relativity.htm

It has alot of information about this "shrinking thing" (just search in CTRL-F - shrink)

Originally Posted by robis97

Okay I found one video where it mentions this "distance shrinking thing"

https://www.youtube.com/watch?v=tflf05x-WVI

He talks about it around 6:45

Maybe I misunderstood him ?

Ok, I watched the full video and I see that what I suspected is accurate.
Pardon the pun... but you are are the right track.
But yes, you misunderstood- but in a very understandable way.

First off, the video is a good clip. But it is not a documentary. Rather, it appears to be a fun educational video that this guy did in his own time for grins.
And he does well.

What I thought you may have been thinking of was Lorentz Contraction. You can get a bit more detail here: Length contraction - Wikipedia, the free encyclopedia
Not exactly lightweight stuff and you can see why I said- Totally understandable.

So going back to your O.P.- No, light does not shrink Spacetime.
However, matter within spacetime does contract.
So we're back to your first idea, "What if light shrinks spacetime so that it arrives at Earth near instantaneously?" No, because there is no mechanism for light to alter spacetime itself and remember: Everything is relative.
For the sake of simplicity, let's replace the beam of light with you in a starship.
You start out very near the Sun and hit the button marked, "Lightspeed (Only push in an emergency)" As you press this button, you hit a button on a stop watch.
You streak to earth at 0.99999999999999999% the speed of light. Upon arrival, you press the button on the stop watch and look at your time. A little bit over 8 minutes.
Remember- Everything is relative so from your perspective- time continued to move at the same rate. But when you land on Earth after the experiment, you will find many years have passed.
And that deals with length contraction and Relativity.
Give me a minute (at light speed) and I will see if I can find another good video that explains it well. Carl Sagans Cosmos series did a good job- along with many others.
EDIT: Suggested a short series in the post below.

EDIT:

Originally Posted by robis97

EDIT: Here I found something interesting.
http://www.webring.org/l/rd?ring=toe...relativity.htm

That site will lead you astray- it contains certain inaccuracies to Relativity- Unless it is your intention to support the hypotheses proposed on that site with strong mathematics and convincing observational evidence, I highly recommend you stick to more reliable Mainstream sources. Understand the Mainstream First. Only when you fully understand current theory should you attempt to question it as much of it is counter-intuitive.

https://www.youtube.com/watch?v=yB0vWbVviTg
You can start with chapter one and work your way through chapter 6. I did not have time to do much more than glaze over this, but it seems pretty well and hopefully others can make recommendations for videos that explain in clear terms for the average person how the concepts work.
For more in depth discussions, there are many threads on the topic on the forums, but you're best off starting a thread with any specific questions that you have. Guitarist, Markus Hanke, Speedfreek, xyzt (he will kill me for listing them both together), and many others are reliable sources for answers on Relativity. There are some who are less reliable but we can cross that bridge only if they try injecting pseudoscience into any of your threads.
If you inject any of your own, expect some harshness.

Well probably it's really hard to tell what is right and what's not. A lot of theories which are used as basis are just theories and are hard to test. So we can't tell what is true and what is not unless we test it.

EDIT: "Remember- Everything is relative so from your perspective- time continued to move at the same rate. But when you land on Earth after the experiment, you will find many years have passed."

So there's no actual point to move in speed of light just because it's even longer(from the point that many years have passed,but you felt it as 8 minutes).

Originally Posted by robis97

Well probably it's really hard to tell what is right and what's not. A lot of theories which are used as basis are just theories and are hard to test. So we can't tell what is true and what is not unless we test it.

No theory can be believed unless it is tested or logically explained.

Originally Posted by robis97

Well probably it's really hard to tell what is right and what's not. A lot of theories which are used as basis are just theories and are hard to test. So we can't tell what is true and what is not unless we test it.

True. But for the record...
Tests of general relativity - Wikipedia, the free encyclopedia
Tests of special relativity - Wikipedia, the free encyclopedia
A Hypothesis is just a hypothesis. But a theory is a hypothesis that has been rigorously tested.
Keep in mind that in common lingo, the word, "Theory" is often misapplied when the speaker means "hypothesis."
A theory is a Model that is used to describe reality as accurately as possible. Theory is supported by observational evidence and testing.
So, the words, "Just a theory" have little meaning.
Unless you mean to say, "Just a hypothesis."

Originally Posted by robis97

So there's no actual point to move in speed of light just because it's even longer(from the point that many years have passed,but you felt it as 8 minutes).

Yes. This is why the idea of some kind of Warp Drive is so appealing.

And at this point we can't actually tell if this time passing is true. If thinking like that : The light we are recieving right now from sun is not 8 minutes old but some years old from our point of view. For the point of view of the sun it's only 8 minutes,but for us it isn't.

EDIT: For me it always bothered that some theories sometimes cancel each other out. Sometimes it sound like scientists are talking about one thing and then they talk about other and the second thing is somehow telling that the first is not true.

Originally Posted by robis97

And at this point we can't actually tell if this time passing is true. If thinking like that : The light we are recieving right now from sun is not 8 minutes old but some years old from our point of view. For the point of view of the sun it's only 8 minutes,but for us it isn't.

You'll hurt your brain thinking like that... "Light" doesn't perceive.

I don't quite understand what it is that you want. But from the perspective of light, it arrives at the same time as it left.

I'm interested in this thread as i've seen this misconception before many times (I believe it is a misconception but I don't have enough understanding to prove the misconception wrong). I've heard that if you were to travel at the speed of light and you wore a watch and timed yourself traveling at the speed of light for 1 second before stopping. The observer watching you would have experience a significantly greater amount of time. And so from here the connection is made that light actually travels faster than light.

This idea does my head in.

The way I deal with this idea, is that velocity and mass is proportional and that mass and time are also related. For example, if i were to stand next to a black hole (somehow), I would experience less time than someone standing on earth. And with this idea, if your physical body was traveling at the speed of light, you would have the mass similar to that of the black hole (or greater) which would cause you to experience that time dilation.

My ideas are more assumptions than anything. Can you guys shine some more light on this seemingly flawed idea?

well by simple recursion; light cannot travel faster then itself. just as much as you cannot overtake yourself.also you can't travel at the speed of light. if you did. the notion of time would no longer be relevant and the internal mechanics would no longer be observable for the outside world. your problem doesn't exist

Originally Posted by SkyNet_Blue

I'm interested in this thread as i've seen this misconception before many times (I believe it is a misconception but I don't have enough understanding to prove the misconception wrong). I've heard that if you were to travel at the speed of light and you wore a watch and timed yourself traveling at the speed of light for 1 second before stopping. The observer watching you would have experience a significantly greater amount of time. And so from here the connection is made that light actually travels faster than light.

This idea does my head in.

The way I deal with this idea, is that velocity and mass is proportional and that mass and time are also related. For example, if i were to stand next to a black hole (somehow), I would experience less time than someone standing on earth. And with this idea, if your physical body was traveling at the speed of light, you would have the mass similar to that of the black hole (or greater) which would cause you to experience that time dilation.

My ideas are more assumptions than anything. Can you guys shine some more light on this seemingly flawed idea?

Well no, for a couple of reasons. For one, you can't travel at the speed of light, only just close to it. Secondly, traveling at near the speed of light does not effect your gravity. The thing to remember is that for the person traveling at this speed, nothing special happens, things are normal for him, and it is everything else that is traveling at near c. His gravity does not increase to equal that that of a black hole.

Here's a different way of thinking of it. Instead of having space and time we have space-time. What's the difference? Space and time might be considered like the directions North/South and East/West. Time is North/south and space is East/West. Ask bunch of people to point North and they will all point the same direction no matter how they are facing. There is a distinction between time and space that everyone agrees to. If you were to ask these people where a particular city was with respect to them they would all say the same answer in terms of North/South and East/West

Space-time is more like front/back and Left/Right. Ask the same bunch of people to point Left and they will point in different directions depending on how they are facing. Their is no Front/back or Left/Right that they all cab agree on. Each defines them relative to himself. Ask them where a particular city is and they will all give different answers in term of front/back and Left/Right. One person would says that it is 40 miles forward and 50 miles to the Left, while another will say that it is 50 miles forward and 40 miles to the left, even though they are standing at the same spot, just facing different directions. Neither is more correct than the other.

Space-time is like this. But instead of facing different directions and a difference in front/back and Left/right measurements, you have relative motion and a difference in space and time measurements.

Ask two people passing each other at a relative speed as to the "location" of an event, and they will give you different answer in terms of time and distance. Oe might say that it takes place x meters away and y sec from now, while the other say that it takes place w meters away and z secs from now. They measure time and space differently.

I can see how this can be confusing, since we don't see this in everyday life. A person standing on the street and a car zipping by on the road don't disagree as to how far it has to drive and how long it will take to reach a given city. But the thing is, they really do, it is just that at the speed that a car drives, the disagreement is so unimaginably tiny, that we don't notice it. It isn't until speeds start to reach a significant fraction of the speed of light that it becomes noticeable. (in our people facing different directions analogy, the car and person so nearly face the same direction, that they don't notice the difference.).

Originally Posted by robis97

Hi.
This morning I had an idea about light and how it moves.

So as we know light moves at light speed which is about 299 792 458 m/s.

Watching some documentaries I noticed something. When something moves at light of speed (or any speed), the distance of the moving object, shrinks a little bit.

So the first idea is this :

• What if the light traveling at the speed of light shrinks the distance, lets say from sun(as the light source) to earth, so much that it reaches earth almost(ALMOST) instantly (or atleast faster than 8 minutes) ?

And another idea I had.

• Maybe the light itself somehow creates(or uses) wormholes and skips a lot of space , instead of traveling the whole distance?

So what do you think about this ? Is this totally false or the idea could be good ?

How light can find shortcut or decrease way
Explain logically
I do not find any fact in it

Originally Posted by Janus

Originally Posted by SkyNet_Blue

I'm interested in this thread as i've seen this misconception before many times (I believe it is a misconception but I don't have enough understanding to prove the misconception wrong). I've heard that if you were to travel at the speed of light and you wore a watch and timed yourself traveling at the speed of light for 1 second before stopping. The observer watching you would have experience a significantly greater amount of time. And so from here the connection is made that light actually travels faster than light.

This idea does my head in.

The way I deal with this idea, is that velocity and mass is proportional and that mass and time are also related. For example, if i were to stand next to a black hole (somehow), I would experience less time than someone standing on earth. And with this idea, if your physical body was traveling at the speed of light, you would have the mass similar to that of the black hole (or greater) which would cause you to experience that time dilation.

My ideas are more assumptions than anything. Can you guys shine some more light on this seemingly flawed idea?

Well no, for a couple of reasons. For one, you can't travel at the speed of light, only just close to it. Secondly, traveling at near the speed of light does not effect your gravity. The thing to remember is that for the person traveling at this speed, nothing special happens, things are normal for him, and it is everything else that is traveling at near c. His gravity does not increase to equal that that of a black hole.

Here's a different way of thinking of it. Instead of having space and time we have space-time. What's the difference? Space and time might be considered like the directions North/South and East/West. Time is North/south and space is East/West. Ask bunch of people to point North and they will all point the same direction no matter how they are facing. There is a distinction between time and space that everyone agrees to. If you were to ask these people where a particular city was with respect to them they would all say the same answer in terms of North/South and East/West

Space-time is more like front/back and Left/Right. Ask the same bunch of people to point Left and they will point in different directions depending on how they are facing. Their is no Front/back or Left/Right that they all cab agree on. Each defines them relative to himself. Ask them where a particular city is and they will all give different answers in term of front/back and Left/Right. One person would says that it is 40 miles forward and 50 miles to the Left, while another will say that it is 50 miles forward and 40 miles to the left, even though they are standing at the same spot, just facing different directions. Neither is more correct than the other.

Space-time is like this. But instead of facing different directions and a difference in front/back and Left/right measurements, you have relative motion and a difference in space and time measurements.

Ask two people passing each other at a relative speed as to the "location" of an event, and they will give you different answer in terms of time and distance. Oe might say that it takes place x meters away and y sec from now, while the other say that it takes place w meters away and z secs from now. They measure time and space differently.

I can see how this can be confusing, since we don't see this in everyday life. A person standing on the street and a car zipping by on the road don't disagree as to how far it has to drive and how long it will take to reach a given city. But the thing is, they really do, it is just that at the speed that a car drives, the disagreement is so unimaginably tiny, that we don't notice it. It isn't until speeds start to reach a significant fraction of the speed of light that it becomes noticeable. (in our people facing different directions analogy, the car and person so nearly face the same direction, that they don't notice the difference.).

When an object goes with speed of light, there must be some force or other natural effect gravity or some other that decrease with speed.
This is reason why motion occurs fast (Change in time flow)

Originally Posted by RAJ_K

When an object goes with speed of light, there must be some force or other natural effect gravity or some other that decrease with speed.

What?

This is reason why motion occurs fast (Change in time flow)

Double what?

If change in flow time occurs when one travel with speed of light, there must be reasons
And it may be reason some effects decreased due to high speed

Originally Posted by RAJ_K

If change in flow time occurs when one travel with speed of light, there must be reasons
And it may be reason some effects decreased due to high speed

What "effects" are "decreased"?
The "change in time flow" occurs at all speeds up to light speed (although negligibly small at low speeds).

If I said about speed of light this does not mean I said opposite to other speed its common sense

Originally Posted by RAJ_K

If I said about speed of light this does not mean I said opposite to other speed its common sense

Your "common sense" has failed you again.
The time dilation occurs AT ALL SPEEDS, not JUST light speed.
You specifically stated "with speed of light" - that implies exclusion of any other speed.
What you should have written was:
if change in flow time occurs when one travels at any speed, there must be reasons

Originally Posted by Dywyddyr

Originally Posted by RAJ_K

If I said about speed of light this does not mean I said opposite to other speed its common sense

Your "common sense" has failed you again.
The time dilation occurs AT ALL SPEEDS, not JUST light speed.
You specifically stated "with speed of light" - that implies exclusion of any other speed.
What you should have written was:
if change in flow time occurs when one travels at any speed, there must be reasons

I never said other time flow remain same at all speed except speed of light

If I say " Eagle can fly" IF take meaning from this that only eagle can fly no other birds fly
than your logic is really great
You did not discuss or even not condemn what I want to say
Just tried to catch words
Great logical man

Moving to New Hypothesis section.

My post before was incited by rage at my inability to prove this guy Speed of Light does *Not* Prove the Universe is Billions of Years Old - YouTube wrong because I myself don't have enough understanding of subject and the maths that goes with it. Turns out i'm the fool because he's a creationist no matter what i tell him. That is beside the point, I want to improve my understanding of relativity one bit at a time.

Originally Posted by Janus

Well no, for a couple of reasons. For one, you can't travel at the speed of light, only just close to it. Secondly, traveling at near the speed of light does not effect your gravity. The thing to remember is that for the person traveling at this speed, nothing special happens, things are normal for him, and it is everything else that is traveling at near c. His gravity does not increase to equal that that of a black hole.

I agree his gravity won't increase with speed. However his relativistic mass does, this is where I make the connection with mass and time dilation.

Originally Posted by Janus

A person standing on the street and a car zipping by on the road don't disagree as to how far it has to drive and how long it will take to reach a given city. But the thing is, they really do, it is just that at the speed that a car drives, the disagreement is so unimaginably tiny, that we don't notice it. It isn't until speeds start to reach a significant fraction of the speed of light that it becomes noticeable.

Does this disagreement occur because the car moving has gained an extremely tiny amount of relativistic mass from motion? If not, why?

Originally Posted by Janus

(in our people facing different directions analogy, the car and person so nearly face the same direction, that they don't notice the difference.).

Is this because effects on the person from gravity of the earth, the location in space and his velocity are so very nearly the same as the car? Even though his velocity is 0 and the car may be 100kmh, in respect to light speed it is a very tiny difference.

Originally Posted by SkyNet_Blue

My post before was incited by rage at my inability to prove this guy Speed of Light does *Not* Prove the Universe is Billions of Years Old - YouTube wrong because I myself don't have enough understanding of subject and the maths that goes with it. Turns out i'm the fool because he's a creationist no matter what i tell him. That is beside the point, I want to improve my understanding of relativity one bit at a time.

Originally Posted by Janus

Well no, for a couple of reasons. For one, you can't travel at the speed of light, only just close to it. Secondly, traveling at near the speed of light does not effect your gravity. The thing to remember is that for the person traveling at this speed, nothing special happens, things are normal for him, and it is everything else that is traveling at near c. His gravity does not increase to equal that that of a black hole.

I agree his gravity won't increase with speed. However his relativistic mass does, this is where I make the connection with mass and time dilation.

Originally Posted by Janus

A person standing on the street and a car zipping by on the road don't disagree as to how far it has to drive and how long it will take to reach a given city. But the thing is, they really do, it is just that at the speed that a car drives, the disagreement is so unimaginably tiny, that we don't notice it. It isn't until speeds start to reach a significant fraction of the speed of light that it becomes noticeable.

Does this disagreement occur because the car moving has gained an extremely tiny amount of relativistic mass from motion? If not, why?

Originally Posted by Janus

(in our people facing different directions analogy, the car and person so nearly face the same direction, that they don't notice the difference.).

Is this because effects on the person from gravity of the earth, the location in space and his velocity are so very nearly the same as the car? Even though his velocity is 0 and the car may be 100kmh, in respect to light speed it is a very tiny difference.

Time dilation due to relative motion has nothing to do with gravity. Special Relativity, which deals with relative motions is a subset of General Relativity, but it is a subset that assumes no gravitational effects.

Even the term "Relativistic mass" has fallen into disfavor as of late. It is generally just called energy.

Originally Posted by SkyNet_Blue

My post before was incited by rage at my inability to prove this guy Speed of Light does *Not* Prove the Universe is Billions of Years Old - YouTube wrong because I myself don't have enough understanding of subject and the maths that goes with it. Turns out i'm the fool because he's a creationist no matter what i tell him. That is beside the point, I want to improve my understanding of relativity one bit at a time.

Originally Posted by Janus

Well no, for a couple of reasons. For one, you can't travel at the speed of light, only just close to it. Secondly, traveling at near the speed of light does not effect your gravity. The thing to remember is that for the person traveling at this speed, nothing special happens, things are normal for him, and it is everything else that is traveling at near c. His gravity does not increase to equal that that of a black hole.

I agree his gravity won't increase with speed. However his relativistic mass does, this is where I make the connection with mass and time dilation.

Originally Posted by Janus

A person standing on the street and a car zipping by on the road don't disagree as to how far it has to drive and how long it will take to reach a given city. But the thing is, they really do, it is just that at the speed that a car drives, the disagreement is so unimaginably tiny, that we don't notice it. It isn't until speeds start to reach a significant fraction of the speed of light that it becomes noticeable.

Does this disagreement occur because the car moving has gained an extremely tiny amount of relativistic mass from motion? If not, why?

Originally Posted by Janus

(in our people facing different directions analogy, the car and person so nearly face the same direction, that they don't notice the difference.).

Is this because effects on the person from gravity of the earth, the location in space and his velocity are so very nearly the same as the car? Even though his velocity is 0 and the car may be 100kmh, in respect to light speed it is a very tiny difference.

Time dilation due to relative motion has nothing to do with gravity. Special Relativity, which deals with relative motions is a subset of General Relativity, but it is a subset that assumes no gravitational effects.

Even the term "Relativistic mass" has fallen into disfavor as of late. It is generally just called energy.

Wow, I research what you just explained, I spent 5 years convinced what I was talking about before to be the way it was (well really just and easy way for me to understand how it is) until now i didn't even know the term invariant mass existed. I looked into relativistic mass which gets messy when using it in maths (didn't fully understand but i kinda get why it is disfavoured), apparently relativistic mass is just an "easy way" of explaining the effects of an object traveling close to speed of light instead of going into invariant mass (i'll do more homework on this). I'll stop talking about this soon, since we're off the main topic of this thread, but i do want to confirm one more thing. Gravity causes time dilation because it bends or warps space-time (like the standing near a black hole compared to standing in space with no masses around you) But completely separate from gravity, just traveling through space causes time dilation just because of the nature of space-time. I'll look into this more, but so far it already seems more complicated than my previous understanding.

Off topic :
I just imagined interesting thing... For example I would have a space ship that can travel at speed of light. Someone would observe me from earth. If I start moving(e.g from sun) at speed of light, he wouldn't see me moving - right? And I would literary appear right after 8 minutes and no one would be able to predict that I'm coming to earth.That's just mind blowing if You think about it. Or there actually is again something different ?

Originally Posted by robis97

Hi.
This morning I had an idea about light and how it moves.

So as we know light moves at light speed which is about 299 792 458 m/s.

Watching some documentaries I noticed something. When something moves
at light of speed (or any speed), the distance of the moving object, shrinks a little bit.

1
When something ( for example - photon ) moves at light of speed
( about 299 792 458 m/s .c=1) then photon itself shrinks into
a flat geometrical figure ( light - photon doesn't shrink outside
distance, road or spacetime )
Conclusion:
According to SRT photon is not a firm particle,
it can change its geometrical form.
2
When photon moves at light of speed ( about 299 792 458 m/s. c=1 )
its own time is zero ( infinite )
Question:
Where does the time come from?
3
Gravity can change the straight movement of photon,
Question:
Where does the gravity come from?
4
In which reference frame photon moves, if gravity ( as an outside object)
can change photon's movement ?
===...

I wish people would stop commenting on things which they really don't understand at all, while making their comments look like physical facts. So to clear this up :

Originally Posted by socratus

According to SRT photon is not a firm particle, it can change its geometrical form.

Photons do not have any "shape", and SRT says no such thing.

When photon moves at light of speed ( about 299 792 458 m/s. c=1 ) its own time is zero ( infinite )

The concept of "proper time" is not defined for a photon, so the above is not only plain wrong, but also completely meaningless.

Where does the gravity come from?

From its source.

In which reference frame photon moves, if gravity ( as an outside object) can change photon's movement ?

The frame of reference of its source.

Originally Posted by socratus

When something ( for example - photon ) moves at light of speed ...

I have the same complaint as Markus, socratus. You are totally clueless about these topics, but you post authoritatively, nonetheless. Then the rest of us have to mop up your pollution.

Please stop.

Learn some physics.

You already have your own blog. You can post your nonsense there all day long. Stay there.

Originally Posted by Janus

Even the term "Relativistic mass" has fallen into disfavor as of late. It is generally just called energy.

I'm not surprised.

Mass in special relativity - Wikipedia, the free encyclopedia

Thus, invariant mass is a natural unit of mass used for systems which are being viewed from their center of momentum frame (COM frame), as when any closed system (for example a bottle of hot gas) is weighed, which requires that the measurement be taken in the center of momentum frame where the system has no net momentum. Under such circumstances the invariant mass is equal to the relativistic mass (discussed below), which is the total energy of the system divided by c (the speed of light) squared.

Compton wavelength - Wikipedia, the free encyclopedia

When the Compton wavelength is divided by 2 * Pi, one obtains a smaller or “reduced” Compton wavelength:
...
The reduced Compton wavelength is a natural representation for mass on the quantum scale, and as such, it appears in many of the fundamental equations of quantum mechanics.