# Has Light got a decay factor?

• 10 months ago · Quote · #1

One either accepts the Standard Model of an expanding universe with galaxies moving at close to the speed of light and getting faster !!!

OR

a non Big bang Universe which doesn't need theories like Dark Matter and Dark Energy to describe it .

The Red Shift is in question as an accurate measurement of distance, and as a consequence, movement. IF light has a decay factor and I highlight the word IF,as it's unproven, then the SS universe model holds.

We don't have to invent new physics to explain the decay factor we only have to find a way how light can decay within the present perameters of current physics.A bit like light being constant to the observer.It took an Einstien to solve the problem by making time a variable.

We have to change or make a variable in the constitusion of light...so as to allow a red shift due to decay rather than just motion.

A possible candidate for a variable component perhaps is when a Photon comes into existance it's massless and then 'aquires' a very small amount of mass through interaction with the Higgs field ,via the Higgs Mechanism, over huge distances but can't be detected or measured because its too small .So small that it doesn't change the maths!?

If a Photon comes into existance  massless and then 'aquires' a very small amount of mass through interaction with the Higgs field ,via the Higgs Mechanism, over huge distances but almost can't be detected or measured because its too small .So small that it doesn't change the maths!? It may be possible to 'weigh' the light from a distant star against light generated in the laboratory. There should be a detectable difference in their 'weight'...if i'm right!

• 10 months ago · Quote · #2
cwwiss wrote:

Has light got a decay factor in exactly the same way as ripples in a pond get longer over distance and time?

There you go.  :)              ;)

• 10 months ago · Quote · #3

Light is always represented with the letter C.Where did you get this formula from?

• 10 months ago · Quote · #4
cwwiss wrote:

Light is always represented with the letter C.Where did you get this formula from?

I don't really understand the decay factor question, but C is the speed of light and as far as I know that's still considered to be an universal physical constant.

• 10 months ago · Quote · #5

The way you are asking the question suggests the following answerable question:

Given a point source, does the intensity of light decrease over distance in the same way the intensity of ripples in a pond from a stone dropped in the center get smaller with distance?

The answer to that is "Yes," and the rate of decrease of the intensity of light over distance from a point source as measured by energy per unit of area perpendicular to the wave propigation is known to follow a formula known as the inverse square law.

$I = \frac{P}{A} = \frac{P}{4 \pi r^2}. \,$

The law says that given a total power output from your point source of P, then at a distance of r from the source, the total intensity (power per unit area) is given by the total power at the source, divided by the area of a sphere of radius r centered on the source.  In other words, the light energy propigates spherically and uniformally from the point source, and intensity decreases over distance inversely proportional to the square of teh distance. Hence, the "inverse square law."

• 10 months ago · Quote · #6

No, i'm asking if there is a decay factor in the wave length..like ripples on a pond or sound waves which lengthen with distance and time. The increased wave length would result in an apparent 'red shift'. The speed will stay the same it's just the wave length that should change.I believe it 'must' change or contravene the law governing the Conservation of Energy.

• 10 months ago · Quote · #7

I just know that with fluorescent light bulbs, it takes them ages to warm up!

• 10 months ago · Quote · #8

Water and air molecules have mass, photons do not.

Light is electromagnetic energy. A photon is a unit of measure of that energy. For the purposes of equations, light can be represented as particles or as wave packets, but those are modeling considerations of how we represent energy.

Sound waves and waves in water are mechanical energy. Mechanical waves degrade over distance because of friction, and the energy is transformed from mechanical energy to heat. Eventually all of the potential energy (represented by whatever is dropped into the water, or making a sound) which has been converted into mechanical energy will be converted again to heat or preserved as potential mechanical energy within a system. That's how mechanical energy functions.

The rules of conservation of energy tell you that energy can not be created or destroyed. That's why when you release potential energy to kinectic energy, the total energy in a mechanical system remains constant. The fact that mechanical energy tends to convert to heat energy due to friction is why we don't have perpetual motion. However, to have light decay is to destroy energy unless it is converted to something else. But there's nothing to convert it too besides another form of energy.

It is possible that light can be absorbed by some material or another, but what happens then is that light is converted to heat. That process can change the wavelength of the light. What happens when you look at a blue object, after all, is that those wavelengths that are blue are being reflected and other wavelengths are being absorbed. But that is not decay, that is simply energy conversion.

• 10 months ago · Quote · #9

I understand that but I think something is wrong somewhere with that model. If light has some energy surely it must therefore have some mass ie E=mc2 . Even if it's almost infinitely small it must have 'some' mass .

• 10 months ago · Quote · #10

That's misapplying Einstein's equation. Total energy is conserved in a system where energy and mass are being converted, such as a nuclear reaction. It does not say that energy _HAS_ mass.

Mass is related to energy because the invariant mass of an object is defined by the equation:  m = sqrt{E2/c4 - p2/c2}

Where E = energy, c- the speed of light, p equals the momentum. It is concievable that you could construct a relativistic frame of reference (a box with perfect mirrored surfaces where absolutely no conversion of light to heat could ever take place), and place within that box some light. In principle the light would add relativistic mass because of the total momentum in the box.

But relativistic mass is not what is meant by 'mass' in the sense of "weighable substance," and the distinction is non-trivial!! What would be being measured in our experiment is not substance, but Energy!

The important point is that E=pc for light. So based on our equation:

m2 = E2/c4 - p2/c= (pc)2/c4 - p2/cp2c2/c4 - p2/c2=p2/c2- p2/c= 0

• 10 months ago · Quote · #11

And if light would have mass it couldn't move at the speed of light

• 10 months ago · Quote · #12

Kingpatser -

Taken from Wiki -

Light exerts physical pressure on objects in its path, a phenomenon which can be deduced by Maxwell's equations, but can be more easily explained by the particle nature of light: photons strike and transfer their momentum.

How can light exert a pressure if it has no mass?

Are you saying that a photon doesn't really exist but can still exert a pressure from it's momentum alone?

• 10 months ago · Quote · #13

E=mc^2 is not the full equation, though.  E^2 = p^2 * c^2 + m^2 * c^4 is more complete (E is energy, p is momentum, m is mass, and c is the speed of light).  For most objects, p is near enough to zero (comparatively, p << m*c) that we can simplify this to E = m*c^2.  For light (and other massless particles), m=0 and E = pc.  Light does have momentum (which is related to its wavelength), and it is this momentum which exerts pressure.

Remember, pressure is force over an area and force can be expressed as a function of momentum: F=m*a, but also F=(dp/dt), which if your not familiar with the notation is the basically the change of momentum with respect to time.  So if a massless particle changes its momentum when it strikes a massive object, then a force is exerted.  And if a force is exerted over an area (even a small area), then there is a pressure.

• 10 months ago · Quote · #14

Cwwiss, yes energy can exert pressure from momentum alone.

And it's not correct to say a photon doesn't exist. But it is incorrect to think of it as a particle. It can be treated as a particle for some modeling considerations. But it is not a particle. It can also be treated as a wave packet for some modelsing considerations, but it is also not a wave. It is energy. Perhaps the best way to think of a photon is as an irreducable event.

• 10 months ago · Quote · #15

not to be rude but how is that a person who can understand all that has a rating that low? (kingpatzer)

• 10 months ago · Quote · #16

Yes, i'm starting to get it now. That full equation  E^2 = p^2 * c^2 + m^2 * c^4

makes much more sense. Light then can have no mass and the equation not end with a big fat zero for E.

However, further research has revealed that though theory predicts zero mass for photons there isn't an experiment to confirm it.All that can be said with confidence is that a photon can not have a mass at rest higher than 3x 10^-27 eV. So a photon may still have a mass between zero and 3 x 10^-27 eV even though it may be at odds with current theory. Is it possible current theory is wrong? We don't have a unifying theory of everything so perhaps something seems to be wrong..somewhere!

• 10 months ago · Quote · #17

Taken from above ref "It is almost certainly impossible to do any experiment that would establish the photon rest mass to be exactly zero.  The best we can hope to do is place limits on it.  A non-zero rest mass would introduce a small damping factor in the inverse square Coulomb law of electrostatic forces.  That means the electrostatic force would be weaker over very large distances".

Could this be the 'decay factor' i'm looking for?

Could it result in the lengthening of the wave over huge distances into the red part of the spectrum ?

• 10 months ago · Quote · #18

The notion of a rest mass for a photon misses the point that  photon is not a particle except for modeling purposes. It is a wave packet of energy.

Our experiments tell us that a very, very small resting mass could be stil be measured. However, that tells us something about our tools, not about photons :)

A photon "at rest" wouldn't be a photon. And if it has any mass at all, it can't move at the speed of light in a vacuum. And the standard model will break. The real question is if photons interact with the Higgs field. If they do, then in some sense they have relativistic mass -- but that mass isn't what one normally means when they talk about mass - it doesn't mean physical substance. It just means that energy is interacting with the Higgs field in some way as the photon moves. If we could stop the photon from moving, without converting that energy in anyway, then the energy would have to do something -- so we'd have some sort of energy/matter conversion in order to conserve energy. But that is entirely a theoretical question that doesn't say anything about reality because we can't remove all momentum from light energy without energy loss in reality.

Remember models aren't the universe. The upper limits of mass that you are seeing are the result of the lower limits of our precision in measuring effects predicted by Coulomb's law. That is, the model doesn't say the photon can have mass. The experimental limits of measuring extremely small events is simply what it is.

And no, it isn't the decay factor you're looking for. The decay factor you're looking for can't exist an the law of conservation of energy hold.

• 10 months ago · Quote · #19
iksarol wrote:

not to be rude but how is that a person who can understand all that has a rating that low? (kingpatzer)

ROFL - not rude, good question :)

Well, unlike math, which I've been doign all my life, I only have really been playing chess seriously for a few years. I played a little  bit in my 30s and  got myself up to 1400 after 2 or 3 years of playing occassionally. I took a decade off due to other interest, and then came back when my OTB rating plummetted to 1200. I am getting better though, my OTB rating has gone from 1200 to over 1500 in the last year. And I'm playing seriously for the first time in my life.

So I'm going through all the learning curve stuff one would expect. And I suck, 'cause, well, relatively novice players suck!

And anything that approaches blitz is simply too much for my old adled brain to deal with :)

• 10 months ago · Quote · #20

As you are a relative novice to chess I am to Physics (pretty obvious I suppose)and I just can't get my head around the idea that a photon of light can travel for billions of years without experiencing some 'decay' .To me that would be perpetual motion which is impossible.

Einstein suspected the big bang model based on the 'red shift' was flawed.Carl Sagan posed the question that all the 'red shift' may not be due entirely to bodies moving away from us. Dark matter,Dark Energy, string theory all seem to have been born out of the need to prop up the big bang theory.We have no idea what they might be..not even a clue! Isn't it much more logical to say that the 'red shift' is due to light decaying and that there aren't distant galaxies moving away from us at nearly the speed of light? That the only reason over 90% of the universe is 'missing' is because we just can't see it ?That the universe is many times larger than the observable universe? That the universe is much older than 13.7billion years?

Humour me - IF the red shift was due to light decaying in the way I have suggested ,based on observable measurements for 'red shifts' is it possible to formulate an equation to calculate that decay factor and if yes what would it be ?