The nature of light

[Bendy Demon]

I have often pondered the nature of visible light; we were told in school how light from the sun, for example, takes about eight minute to travel from its source to us (the earth, that is).

This always seemed odd to me because as I understood, science has not really determined if visible light is a particle, a wave, both or perhaps something else. (maybe I am wrong on that too)

After all we are not really that far from the sun in terms of astronomical distances so why would it take so long and if this were true then why would we not see any flickering?

If light is that slow then the other forms of energy released from the sun would be obviously slower so if the sun was to go out right now, we are told that we would not know of it for a full eight minutes and I suspect that we would still have a few minutes of life left anyways because the other wavelengths that the sun produced will not have reached us yet so even in the total darkness we'd still live...for a tiny bit anyways.

I am no scientist and I have no intentions of pretending to be one but for some reason some of these theories just do not seem quite...I don't know...accurate.

[Imaginarynumber1]

On average the earth is 150 million kilometers from the sun. Light travels at 300000 kilometers a second. Divide and you get 500 seconds, or 8 minutes and 20 seconds.

Photons exhibit wave particle duality. The have properties of both waves and particles.

Edited October 14, 2014 by Imaginarynumber1

[Bendy Demon]

Well.yes, I kind get that but it just seems to me that while photons can exhibit the properties of both waves and particles, it still seems to imply that there is something in physic scientists have yet to identify.

Photons may have the properties of both wave and particle but they still seem to be something else; something outside of what science currently understands.

I did say I was not a scientist so trying to adequately express my thoughts on this matter are a tad cumbersome.

[Imaginarynumber1]

Well.yes, I kind get that but it just seems to me that while photons can exhibit the properties of both waves and particles, it still seems to imply that there is something in physic scientists have yet to identify.

Photons may have the properties of both wave and particle but they still seem to be something else; something outside of what science currently understands.

I did say I was not a scientist so trying to adequately express my thoughts on this matter are a tad cumbersome.

Its easier if you think of it as a particle with waves encompassing it.

The photon is on of the most understood elemetry particles.

[pallidin]

Technically, a photon is not a particle. Though it can behave as such under certain circumstances.

It's defined as a "wavicle", simultaneously possessing the properties of a particle and a wave.

[Bendy Demon]

Kind of an odd concept considering that one would think of a particle of any frequency to either be one or the other at any given time, not both.

Still, it would seem that a new category is needed to define particles (I use the term loosely) whose nature does outside of known or established parameters.

Edited October 14, 2014 by Ryu

[pallidin]

Kind of an odd concept considering that one would think of a particle of any frequency to either be one or the other at any given time, not both.

Still, it would seem that a new category is needed to define particles (I use the term loosely) whose nature does outside of known or established parameters.

Bear in mind that a photon is NOT considered a "pure" particle. It's a "wavicle"

A photon, though affected by strong gravity, has ZERO rest mass. This allows it to express itself immediately at the speed of light... there is no acceleration.

[Sylus]

What is a photon? What is it made up of? Why does it exist? Why is it immaterial? Why is it massless? Why does it observe no passing of time (or infinitely slow)? Why does it exhibit dual properties of particles and waves? Why is the constant of light constant? For what sufficient reason should light travel at this speed rather than that speed? If a photon is massless, how can a black hole 'swallow' it? Why are no photons visible in a black hole?

[Merc14]

What is a photon? What is it made up of? Why does it exist? Why is it immaterial? Why is it massless? Why does it observe no passing of time (or infinitely slow)? Why does it exhibit dual properties of particles and waves? Why is the constant of light constant? For what sufficient reason should light travel at this speed rather than that speed? If a photon is massless, how can a black hole 'swallow' it? Why are no photons visible in a black hole?

You need to get a degree in physics. Hell, if photons drive you nuts, wait till you look into quantum physics. Some very smart people here, though, that I so enjoy learning from and you have asked some great questions. I'll enjoy seeing what is posted but this stuff is far above my paygrade.

Edited October 15, 2014 by Merc14

[StarMountainKid]

For what sufficient reason should light travel at this speed rather than that speed? If a photon is massless, how can a black hole 'swallow' it? Why are no photons visible in a black hole?

Light travels at the speed it does because of the vacuum permittivity and vacuum permeability in free space, or the electromagnetic conductivity and resistivity of space.

Photons follow the curvature of space, which is due to gravitational fields. The gravitational field of a black hole deforms space in such a way that within the event horizon the paths of photons always point into the black hole.

Edited October 15, 2014 by StarMountainKid

[Sylus]

What is a vacuum? Space devoid of matter? Then what is space? But even then, given the physical constant in a 'vacuum', the real question is why the constant is this number of units rather than one unit above or below -- why did nature choose the constant she did? Why does light travel 186,282 miles per second in a vacuum rather than 186,283 miles per second? And bringing up quantity of measure does not viably answer the question.

How and why does a black hole deform space? What is a black hole, actually? Where do the photons go once they pass the event horizon?

[back to earth]

I suppose I should say something about the construction of light ...

In essence it consists ( like the theories, and this thread) in a series of ? ! ? ! ? ! ? ...

[Jacques Terreur]

What is a vacuum? Space devoid of matter? Then what is space? But even then, given the physical constant in a 'vacuum', the real question is why the constant is this number of units rather than one unit above or below -- why did nature choose the constant she did? Why does light travel 186,282 miles per second in a vacuum rather than 186,283 miles per second? And bringing up quantity of measure does not viably answer the question.

How and why does a black hole deform space? What is a black hole, actually? Where do the photons go once they pass the event horizon?

Is this a "stream of conciousness" essay? Do you know the answers to those questions already? Or are you actually looking for an answer? Are you a physics Professor that just can't let go? Or a person who had just one coffee too many? Or 12?

[StarMountainKid]

Why, why, why? Why Existence and not Non-Existence?

The answer is, Existence is the result a Hyper-Dimensional Probability Generating Dynamo kicking out discrete random variables of probability mass functions in which the radius of convergence is a first order geometric probability distribution with a variance of (1 - p)/p^2, in which the parameter estimation of maximum likelihood conjugate follows a negative binomial distribution. The recurrence relation is independent of negative distribution parameters, derived from a psudorandom number generator that precludes hypergeometric covariance matrix vectors. Of course, the conditional mean variance density function is statistically deferred by multivariate analysis and multidimensional scaling.

I could go on in greater detail, but you get the idea. The question of why does this Hyper-Dimensional Probability Dynamo exist and why is it kicking out all these probabilities (of which our universe is one) is a meaningless question, due to the fact that the question itself is one of the probabilities the Dynamo kicks out, so to say. The entire process is a recursive closed loop, in that any questions of the nature of the Dynamo itself are an intrinsic result of the Dynamo's function.

Resistance is useless.

Edited October 15, 2014 by StarMountainKid

[+Noteverythingisaconspiracy]

What is a vacuum? Space devoid of matter? Then what is space? But even then, given the physical constant in a 'vacuum', the real question is why the constant is this number of units rather than one unit above or below -- why did nature choose the constant she did? Why does light travel 186,282 miles per second in a vacuum rather than 186,283 miles per second? And bringing up quantity of measure does not viably answer the question.

How and why does a black hole deform space? What is a black hole, actually? Where do the photons go once they pass the event Horizon?

A vacuum is defined as "a Space that is devoid of matter". Most of the times the term vacuum is used, it is actually a partial vacuum. Even in the deepest of space, there are nearly allways some stray atoms present.

Space is "the boundless three-dimensional extent in which objects and events have relative position and direction". Basically space is everywhere in the universe. The term outer space is legally considered to be anything more than 100 km above the earth's surface.

The rest of your questions are, as Merc14 put it, far above my pay grade !

[spud the mackem]

So where does the light go when you turn the switch to Off in a room.

[+Noteverythingisaconspiracy]

So where does the light go when you turn the switch to Off in a room.

Isn't it obvious: It goes to sleep

[Bendy Demon]

Bear in mind that a photon is NOT considered a "pure" particle. It's a "wavicle"

A photon, though affected by strong gravity, has ZERO rest mass. This allows it to express itself immediately at the speed of light... there is no acceleration.

Sorry..for a moment when I seen "wavicle" I thought of some sort of cosmic popsicle.

So if a photon is affected by gravity even though it lack mass (matter) then this apparently indicates that gravity itself is not what we originally assumed it was.

However we are also told that gravity is relatively weak which then puts into question the nature of black holes which are said to be so strong that not even light escapes.

Well..if light is comprised of photons, has no mass and is affected by gravity nonetheless then light is not being trapped or "sucked" into anything but merely bent/distorted, right.

So therefore it would seem that the speed of light is not a constant if there are variables that can so easily affect what is basically mass-less stuff.

Also it would seem, from my perspective, that a field of gravity has a rather limited reach and would seem to become..I don't know...spotty and unstable the further out it emanates from its source.

P.S: A reminder..I am not a scientist so my ramblings, no doubt, seems stupid and all.

[sepulchrave]

I have a Ph.D. in physics.

Here goes nothing:

I have often pondered the nature of visible light; we were told in school how light from the sun, for example, takes about eight minute to travel from its source to us (the earth, that is).

This always seemed odd to me because as I understood, science has not really determined if visible light is a particle, a wave, both or perhaps something else. (maybe I am wrong on that too)

Pallidin addressed this by calling a photon a ``wavicle'', but he made a serious error in his explanation.

ALL objects (including macroscopic composite ones, like you and I) exist in a definite state that is determined by their interaction with the environment.

In some situations, this state is very localized in space; we call this state a ``particle''.

In other situations, this state is very localized in momentum; we call this state a ``wave''.

The Heisenberg uncertainty relation puts a lower limit on the amount of localization that can occur in both states simultaneously.

Pallidin's error was claiming a ``wavicle'' simultaneously possesses the properties of a particle and a wave; it definitely does not. Rather a photon, like any object, can be described as a wave in some situations and as a particle in other situations.

I also think it is very important to stress that ``particles'' and ``waves'' are only two of an infinite number of states that an object can have.

For example, students of undergraduate quantum mechanics should recognize that the ground state of a hydrogen atom or the ground state of a quantum harmonic oscillator are neither particles nor waves.

Personally, I think there is a lot of unnecessary confusion about ``wave-particle duality''; since in my experience most people don't have a clear grasp of what a ``particle'' or a ``wave'' is to begin with.

After all we are not really that far from the sun in terms of astronomical distances so why would it take so long and if this were true then why would we not see any flickering?

The astronomical distance was already accurately addressed. We do not see any flickering because the Sun is constantly emitting photons, and (more to the point) the Sun is so bright it saturates our vision.

The intensity of the Sun does oscillate a bit, but we cannot see this because most of the oscillation occurs outside our visible range, and the oscillation within the visible range is too small - we are always blinded by looking directly at the Sun regardless of any minor ``flickering''.

If light is that slow then the other forms of energy released from the sun would be obviously slower so if the sun was to go out right now, we are told that we would not know of it for a full eight minutes and I suspect that we would still have a few minutes of life left anyways because the other wavelengths that the sun produced will not have reached us yet so even in the total darkness we'd still live...for a tiny bit anyways.

All electromagnetic radiation travels at the same speed.

Of course you are correct, we would not die after 8 minutes if the Sun somehow went out.

If I had to guess, I'd say we could live for two or three days before we all froze to death. Consider how cold it gets at night, and extrapolate.

What is a photon? What is it made up of? Why does it exist?

A discrete excitation of the electromagnetic field.

As other posters have alluded to, we understand electricity and magnetism from subatomic to galactic scales. We understand these phenomena better than we understand anything else in the Universe.

Photons exist because we live in a Universe that possesses a vector gauge field with one degree of freedom, and this Universe also possesses a maximum propagation speed which concenquently doubles this vector gauge field (electric+magnetic parts), and finally this Universe also possesses some sort of lower limit to information/entropy density which consequently only admits discrete excitations of this vector gauge field.

Why is the Universe the way it is? I have no idea.

Why is it immaterial?

It isn't. A photon, like every other thing in the Universe, is composed of energy.

Why is it massless?

It isn't. A photon has an effective mass via the relationship E = mc².

However the only mechanism a photon has to store this mass/energy is through motion.

The reasons have to do with electroweak symmetry breaking; there are several other gauge bosons that do have an ``intrinsic potential energy'', or a ``rest mass''.

Why does it observe no passing of time (or infinitely slow)?

No elementary particle observes any passing of time, because elementary particles have no intrinsic entropy.

Because our Universe possesses a maximum propagation speed (otherwise known as the speed of light), composite objects must experience a slowing of time when approaching this speed limit in order to preserve Lorentz invariance.

Why is the Universe the way it is? See my answer above.

Why does it exhibit dual properties of particles and waves?

See my answer above.

The succinct answer is: ``Ever object naturally adopts an eigenstate of the Hamiltonian imposed by its environment''.

Sometimes that state is a wave, sometimes that state is a particle, most of the time it is something else.

Why is the constant of light constant? For what sufficient reason should light travel at this speed rather than that speed?

Our Universe possesses a maximum propagation speed, and this speed appears to be constant.

StarMountainKid addressed the rest of this issue.

If a photon is massless, how can a black hole 'swallow' it? Why are no photons visible in a black hole?

StarMountainKid addressed this issue as well, but to add to his answer:

In the absence of an external force, all objects will follow a geodesic that is defined by the curvature of space. Inside the event horizon of a black hole the curvature is so intense that no geodesics can pass back beyond the event horizon.

Secondly, photons, like all elementary particles, exist until they decay or are annihilated. Photons cannot decay, but they are annihilated (or absorbed) by matter quite easily (this should be obvious; black objects always appear darker than white objects subject to the same lighting because black objecst absorb more photons than white objects do). There is obviously plenty of matter inside a black hole.

What is a vacuum? Space devoid of matter? Then what is space? But even then, given the physical constant in a 'vacuum', the real question is why the constant is this number of units rather than one unit above or below -- why did nature choose the constant she did? Why does light travel 186,282 miles per second in a vacuum rather than 186,283 miles per second? And bringing up quantity of measure does not viably answer the question.

Irrelevant. Only the value of dimensionless constants are significant. The speed of light is 1.0 in natural units.

Why is the fine structure constant approximately 1/137; or why is pi 3.14159... are far more relevant questions.

How and why does a black hole deform space?

All space is deformed by the presence of mass and energy.

Basically, the curvature of space - most generally described by the Reimannian Curvature Tensor - can be related to the Stress-Energy tensor consisting of mass, energy, pressure, and stress.

A black hole is simply a case of sufficiently high density causing some rather extreme deformations.

What is a black hole, actually?

Any object of sufficient density to create an event horizon. For most situations, the Schwarzschild radius is an appropriate measure of the event horizon and it is quite easy to calculate.

As soon as an object is entirely contained within its event horizon, it becomes a black hole.

Whether that object truly collapses into a singularity is unknown (it probably doesn't due to quantum mechanical effects, but who knows).

Where do the photons go once they pass the event horizon?

Same thing that they normally do. They propagate along a geodesic until they are absorbed by some matter.

If a black hole truly is a singularity, then the photons probably spiral around it for a very long time.

[Emma_Acid]

After all we are not really that far from the sun in terms of astronomical distances so why would it take so long and if this were true then why would we not see any flickering?

Why would it flicker?

I am no scientist and I have no intentions of pretending to be one but for some reason some of these theories just do not seem quite...I don't know...accurate.

In the nicest possible way, just because you don't understand something, doesn't mean no one does.

So if a photon is affected by gravity even though it lack mass (matter) then this apparently indicates that gravity itself is not what we originally assumed it was.

Gravity is just the curving of space. Around a black hole is curves so much that light has to travel along these curves, and can't spread freely away from the object.

However we are also told that gravity is relatively weak which then puts into question the nature of black holes which are said to be so strong that not even light escapes.

The important word here is "relatively". Gravity is weak only when compared to the other fundamental forces - the two nuclear forces and the electromagnetic force, which are much much stronger.

Also it would seem, from my perspective, that a field of gravity has a rather limited reach and would seem to become..I don't know...spotty and unstable the further out it emanates from its source.

Not spotty, but it of course becomes weaker. It's called the inverse square law, and its the same ratio that radiowaves etc reduce by when you get further from the source. But this is obvious - otherwise there would be no variations in gravity anywhere in the universe.

[Bendy Demon]

All electromagnetic radiation travels at the same speed.

Thank you for the explanations however this one quote seems a bit..puzzling to me.

The electromagnetic spectrum (what we loosely call 'light' ) has different aspects, right? From gamma to microwave and so on. My understanding is that certain frequencies are used because they travel faster and farther than others and some need less energy when being sent.

Otherwise it just wouldn't matter.

However I agree that a particle has to be one thing or another, not both even though it acts like it. Kind of like saying a bird is both a mammal and a reptile because it shares similar properties at the same time (being warm blooded yet laying eggs, for example. It is neither of course and has its own category.)

Also the concept that anything can exist without some discernible mass, no matter how minute seems bizarre to me. If it exists and has an effect on its surroundings even the extent is miniscule then it has to have some mass.

Anyways, thanks for taking the time to explain. I am still puzzled but not as much now.

Why would it flicker?

If light takes eight minutes to reach us then it would indicate it travels in waves, right? Therefore I figured some visual oscillation would be detected.

In the nicest possible way, just because you don't understand something, doesn't mean no one does.

Whoa there! Where did I EVER say that?

All I did was indicate that I am not a scientist. I NEVER said that no one else understood these theories.

Edited October 15, 2014 by Ryu

[Bendy Demon]

Edited and combined

Edited October 15, 2014 by Ryu

[Sylus]

"The answer is, Existence is the result a Hyper-Dimensional Probability Generating Dynamo kicking out discrete random variables of probability mass functions in which the radius of convergence is a first order geometric probability distribution with a variance of (1 - p)/p^2, in which the parameter estimation of maximum likelihood conjugate follows a negative binomial distribution. The recurrence relation is independent of negative distribution parameters, derived from a psudorandom number generator that precludes hypergeometric covariance matrix vectors. Of course, the conditional mean variance density function is statistically deferred by multivariate analysis and multidimensional scaling."

Does anybody really believe this pseudointellectual mumble jumble? Medieval thinker Roger Bacon, in his work titled "Open Majus", identified 4 sources of ignorance, one of which is the "display of wisdom that simply covers up ignorance". This is the most nihilistic answer a person could produce. You basically said that the universe is random and meaningless and even to question why this is so is simply the dead universe spiting out a random, meaningless function. I can tell you, you are 100% wrong.

Where were the laws of physics before the Big Bang?

[Sylus]

"A photon, like every other thing in the universe, is composed of energy."

What is energy and why can it not be destroyed or created?

The answer to the 'wavicle' paradox is this: a photon (or any other 'wavicle') is a particle that has a wave trajectory inherently built into it (defined by the generalized Euler formula).

Photons are not particles that magically shapeshift into waves due to some situational necessity. How would this shapeshift be even possible and what laws would guide this?

[J. K.]

Not a physicist here either.

1) I have always wondered where photons go after they strike our rods and cones.

2) With all the photons flying around, how can we see distinction in objects rather than just diffused random static? There's probably a better way to phrase that question.

3) We see light reflected from objects in our field of vision, correct? So...we don't actually see the objects themselves, just reflected light. That makes my brain hurt.