Ask any question you want about Physics

originally posted by: darkorange
you said
They are densely packed, but they are photons, not sardines. Two sardines can't occupy the same space at the same time, but I don't know of any reason why millions or even billions of photons can't be on top of each other, as they leave the star.

On the top of each other. Cool. How about photons are waves on emit and these waves overlap normally, like waves do?


You said
If you set up an array of photon detectors around the annihilation event, and a detector detects a photon, doesn't the location of that detector tell you what direction the photon went?

And on every number of collisions same detector catches photon or it might be different detector other try around?


Thanks.

DO.

Ok im going to differ with Arbitrageur slightly on this. First this subject is a matter of debate between physicists. Does photons collide or more interfere with each other. What it comes down to is definition here some say photons do not interact with each other. This is true sort of got to love physics. we know that light can certainly interact in a medium. In a vacuum it is more different but ill come back to that. Light interacts with things like glass,water or even a wall. We see it refract, scatter, reflect and it is emitted from materials like in a light bulb or LED. There is an effect called frequency mixing For example if i took a green laser and a red laser infra red laser bounce them off a mirror i get a blue laser. This is simply two waves combining. Now im sort of cheating here slightly because of course as we talked about earlier electrons are absorbing the two lasers and remitting them as stream of photons at a different energy level. Nonlinear optics requires a medium which has a strong optical response. But the reason i mention this is because we are dealing with the sun. As was mentioned photons in the sun do indeed interact eventually forming white light. We can break down the suns light into its individual parts again by say using a prism. So in the sun they all interact and combine.

But now lets look at light in a vacuum shall we im going to refer to whats called quantum imaging. So let us think what happens with just a pair of photons coming onto this beamsplitter we get two out put beams will call them 1 and 2, this is what we would expect to happen. However If the phase is correct between the two photons remember that you have to think of them as both particle and waves. Instead of getting two streams of photons we again get 1 beam either travelling along beam 1 or 2. So whats happening here?? Simple were getting interference from our beamsplitter. Now we lets put 4 photons or 2 pair into our splitter So now we have 4 photons hitting our splitter. Now we can see that when we have two pairs of photons this interference has twice the frequency as for a single pair. If we now try it for three pairs the frequency is tripled and so on. This is no longer interference, but direct proof that photons do indeed interact and the interaction is dependent on the number of photons in the system. This is how we can use this for quantum holography or quantum imaging. Now not to mislead here this does require our photons to have the same charge and frequency but they definitely interact. So can photons interact under certain circumstances yes they can. And thats why i only partially disagree with him under most circumstances he is correct.

Got to love physics we always find exceptions to the rule but thats what makes it fun,

originally posted by: Arbitrageur
You can click the quote symbol on top of the reply box to quote me, instead of writing out "you said".

originally posted by: darkorange
On the top of each other. Cool. How about photons are waves on emit and these waves overlap normally, like waves do?

In some ways they are like waves and in some ways they are like particles. Sure you can think of waves overlapping, but if you try to think of them as just waves, your hypothesis will fail. The photons detected at the hubble telescope do not show the type of effect we would observe if photons were just waves. It might detect one photon, then 20 seconds another photon, then 30 seconds later another photon, from a given distant star. This is not wave-like behavior.

And on every number of collisions same detector catches photon or it might be different detector other try around?

I don't understand the question. If you repeat the experiment, the photon from the next experiment can go in the same direction or in a different direction.

I just needed to highlight not quote entire jam from you.

So, in between those 20 seconds the star is not visible?
You have to come up with better argument than this. Honestly.

DO.

originally posted by: darkorange

originally posted by: Arbitrageur
You can click the quote symbol on top of the reply box to quote me, instead of writing out "you said".

originally posted by: darkorange
On the top of each other. Cool. How about photons are waves on emit and these waves overlap normally, like waves do?

In some ways they are like waves and in some ways they are like particles. Sure you can think of waves overlapping, but if you try to think of them as just waves, your hypothesis will fail. The photons detected at the hubble telescope do not show the type of effect we would observe if photons were just waves. It might detect one photon, then 20 seconds another photon, then 30 seconds later another photon, from a given distant star. This is not wave-like behavior.

And on every number of collisions same detector catches photon or it might be different detector other try around?

I don't understand the question. If you repeat the experiment, the photon from the next experiment can go in the same direction or in a different direction.

I just needed to highlight not quote entire jam from you.

So, in between those 20 seconds the star is not visible?
You have to come up with better argument than this. Honestly.

DO.

A distant star like the sun, thousands of light years away, could be so faint that only one photon might arrive per square meter every few hundred seconds. As you get further away the light is spread out over a larger area so that the brightness (intensity per area) decreases. Why distant stars a dimmer. What does this mean well it means the number of photons per meter decreases. So with distance our photons have to be very accurate to hit the lens of the Hubble telescope. And some could miss by a meter others by a kilometer. What was a constant stream of photons has been broken up by distance as it expands into space. This would happen if light was just a wave but also we would see something else happen most of our sky would go black. Because as the waves increased with distance they could end up kilometers wide again that doesnt happen.

a reply to: dragonridr

How much of our comprehension of the fundamental nature of light is effected by the fact that we always ultimately measure light using 'a lens like thing' and a 'discrete sensor like thing' and maybe even wires? And then again that information transported through lens (eye) and wires (optical nerve) onto a screen (mind/imagination/memory) which then has to travel through yet another set?

Also with the telescopes on that get 1 per photon per whatever, could it be that light from those planets gets 'broken up' in some way by the gravity well of the sun, by interacting with gravity fields of other bodies rotating and dark matter, and then also the earths gravity well, which may be rotating as the earth rotates, you can consider if either scenario would force non trivial conclusions in relation to my question. And so light may be purely a wave, but the way that the earth is spinning so faster and moving so fast and with all the gravity wells in the way of a distance star, as even that interstellar space is itself the galaxies gravity well and may not only be rotating itself, but also travling through intergalactic space linearly (via expansion), that the light from a distant star just out of all the directions it can aim, of course because there is so much energy release there is so much directional release, from a relative sphere and how the points would separate as distance increases, even a perfect sphere must be composed of ultimately a finite quantity of points, and these points then extended away from the sphere surface in all their finite point directions, will prove over space and time to have increasing distance between them? Quite the interesting seeming fact.

How would a PION beam work?
What would it look like if used?

When I was a kid I tried jumping off the roof of a 2 story house with an umbrella as a parachute...Mary Poppins style.
It was a total failure.
The supporting rungs collapsed upwards and I dropped like a rock...breaking my ankle in the process.
I am curious if it would be possible to make a portable umbrella/parachute that would make it possible to make a 20 foot jump successfully.
What sort of surface area would be necessary and what sort of force would the braces have to sustain?
Is this possible with something the size of a portable umbrella?

a reply to: ImaFungi

Ok a lens Focuses photons to a single point usually a detector or say photographic paper, It increases the number we see so not sure how you figure this somehow decreases it. As ras as optic nerve and such your over thinking it has nothing to do with it our brain was built to comprehend visual stimuli 100s of thousands of years ago. Now gravity can have an effect on light causing it to bend but if it was a continuous wave would matter word it. Only because its discrete packets that we see things like gravitational lensing. As far as spinning and so forth to a photon leaving the surface doesnt matter how fast the sun is spinning. Its direction is set, most stars give off photons in all directions. The only thing close to your example would be a pulsar which sends out a beam and the spinning causes that beam to continually face in a new direction.

originally posted by: skunkape23
When I was a kid I tried jumping off the roof of a 2 story house with an umbrella as a parachute...Mary Poppins style.
It was a total failure.
The supporting rungs collapsed upwards and I dropped like a rock...breaking my ankle in the process.
I am curious if it would be possible to make a portable umbrella/parachute that would make it possible to make a 20 foot jump successfully.
What sort of surface area would be necessary and what sort of force would the braces have to sustain?
Is this possible with something the size of a portable umbrella?

Simple answer is no you could never make an umbrella big enough or for that matter strong enough. the average parachute is probably around 300 sq ft. In order to make something big enough to hold a person your talking about building a plane like the wright brothers. There plane was just an over sized parachute made of canvas and wood metal was to heavy. If you want to play with calculations here is a handy program skydivers use.

www.dropzone.com...

The discovery of the electron in 1897 was a key to understanding the phenomena, which Maxwell didn't know about since he died in 1879. His equations do show a beautiful reciprocity between electricity and magnetism in that a time variance of one induces the other.

I'm probably misunderstanding it and/or being overly critical. Thomson discovered a key to understanding the phenomenon (electricity) which we call electrons (he called them corpuscles). How do we know electrons exist (the discovery of electrons in 1897)?.. Because Thomson discovered the electron. Seems like it's begging the question.

No doubt what so ever, he discovered phenomena within a phenomenon which he was able to measure and it is valid.

Or, rather, have there been any serious experiments looking at the reciprocity of their relationship? That is, examining EM from a magnetic denominator?

We have hypothesized but never found a magnetic monopole. Some monopole-like behavior has been demonstrated in substances like Bose-Einstein condensate, but that's definitely not a true monopole. It would probably take a discovery of something like a magnetic monopole to have any chance of seeing the relationship as fully reciprocal and even then if the existence of magnetic monopoles turns out to be something which only existed briefly after the big bang, such a discovery wouldn't give magnetism full reciprocal status.

So it has to be a mono-pole? Like a quark?

Charges less than an elementary charge[edit]
There are two known sorts of exceptions to the indivisibility of the elementary charge: quarks and quasiparticles.

*Quarks, first posited in the 1960s, have quantized charge, but the charge is quantized into multiples of 1⁄3 e. However, quarks cannot be seen as isolated particles; they exist only in groupings, and stable groupings of quarks (such as a proton, which consists of three quarks) all have charges that are integer multiples of e. For this reason, either 1 e or 1⁄3 e can be justifiably considered to be "the quantum of charge", depending on the context.

*Quasiparticles are not particles as such, but rather an emergent entity in a complex material system that behaves like a particle. In 1982 Robert Laughlin explained the fractional quantum Hall effect by postulating the existence of fractionally-charged quasiparticles. This theory is now widely accepted, but this is not considered to be a violation of the principle of charge quantization, since quasiparticles are not elementary particles.

Since the electron which dominates electricity, is apparently responsible for most electrical and magnetic phenomena, wouldn't we be justifiably biased in thinking of magnetism perhaps being secondary to electricity, now that we know about the electron (which Maxwell didn't)?

Could you elaborate on that if you, or others, have time and patience. Thanks in advance!

originally posted by: dragonridr
So can photons interact under certain circumstances yes they can. And thats why i only partially disagree with him under most circumstances he is correct.

Got to love physics we always find exceptions to the rule but thats what makes it fun,

The exceptions I was referring to are mentioned in this article, which says that such interactions had never been observed, but that was in 2013. I don't know if they might have been observed interacting since, but it was predicted:

physics.aps.org...

Theory suggests that the Large Hadron Collider might be able to detect for the first time the very weak interaction between two photons.

Despite what movie lightsabers suggest, light beams pass through each other without effect. However, two photons will, on rare occasion, bounce off each other. This elastic photon-photon scattering, which occurs via intermediate particles, has never been observed directly, but a new analysis in Physical Review Letters shows that the Large Hadron Collider (LHC) at CERN could detect around 20 photon-photon events per year.

This sounds a little more analogous to photons leaving a star trying to collide than your splitter example, though that's interesting, got a link for further reading on that?

originally posted by: darkorange
I just needed to highlight not quote entire jam from you.

That's what I was suggesting you do. In fact you're not supposed to quote the whole post according to ATS. You can click the "quote" part and ATS has actually asked us to "trim" that to just the relevant part you need to cite.

So, in between those 20 seconds the star is not visible?
You have to come up with better argument than this. Honestly.

Of course there are more arguments not the least of which is the double slit experiments and many variations of it, but your comment is hardly a rebuttal to the particle-like nature of the photons observed from distant stars.

You need to develop a better understanding of the implications of waves versus particles, as it's not even apparent you understand why that observation doesn't fit well with wave behavior. Dragonridr does and explained some of the implications.

a reply to: dragonridr
Right.

originally posted by: Flux8
I'm probably misunderstanding it and/or being overly critical. Thomson discovered a key to understanding the phenomenon (electricity) which we call electrons (he called them corpuscles). How do we know electrons exist (the discovery of electrons in 1897)?.. Because Thomson discovered the electron. Seems like it's begging the question.

If Thompson was the only one to suggest these corpuscles, perhaps. But there are many, many experiments and applications of electrons, which we need to understand pretty well to make the very computer you're using to ask your question. While Thompson is given credit for the discovery, most research upon which we rely today was done after Thompson.

For example Thompson had no idea of the quantum mechanical properties of the "corpuscles" he discovered, as quantum mechanics hadn't been discovered yet.

So it has to be a mono-pole? Like a quark?

Nature is the way it is. If you want to claim that electricity and magnetism are completely symmetrical, I find it a weak claim if you can't find magnetic pole carriers as we find charge carriers:

plato.stanford.edu...

The 19th-century theory of electromagnetism postulated numerous analogies between electric charge and magnetic charge. One theoretical difference is that magnetic charges must always come in oppositely-charged pairs, called “dipoles” (as in the North and South poles of a bar magnet), whereas single electric charges, or “monopoles,” can exist in isolation. However, no actual magnetic monopole had ever been observed. Physicists began to wonder whether there was some theoretical reason why monopoles could not exist. It was initially thought that the newly developed theory of quantum mechanics ruled out the possibility of magnetic monopoles, and this is why none had ever been detected. However, in 1931 the physicist Paul Dirac showed that the existence of monopoles is consistent with quantum mechanics, although it is not required by it. Dirac went on to assert the existence of monopoles, arguing that their existence is not ruled out by theory and that “under these circumstances one would be surprised if Nature had made no use of it” (Dirac 1930, p. 71, note 5). This appeal to plenitude was widely—though not universally—accepted by other physicists.

Could you elaborate on that if you, or others, have time and patience. Thanks in advance!

The citation above highlights my meaning.

a reply to: Arbitrageur

Here is a paper on what i was referring to .

www.researchgate.net...

However also here we see the interactions again just didnt want to explain this one lol.

www.iflscience.com...

a reply to: dragonridr
Thanks for the links.

The electron changing from a particle to a wave just by us looking or observing it always fascinated me. Does that mean our mind changes matter ? Our thinking can create or change the universe? And if observing things can change their physical properties, does that mean our minds are really powerful or maybe our concept of reality is not what we think ?
Sometimes I feel there is nothing we can scientifically prove because reality may not be what we think it is.

originally posted by: ImaFungi
a reply to: dragonridr

Also with the telescopes on that get 1 per photon per whatever, could it be that light from those planets gets 'broken up' in some way by the gravity well of the sun, by interacting with gravity fields of other bodies rotating and dark matter, and then also the earths gravity well, which may be rotating as the earth rotates, you can consider if either scenario would force non trivial conclusions in relation to my question. And so light may be purely a wave, but the way that the earth is spinning so faster and moving so fast and with all the gravity wells in the way of a distance star, as even that interstellar space is itself the galaxies gravity well and may not only be rotating itself, but also travling through intergalactic space linearly (via expansion), that the light from a distant star just out of all the directions it can aim, of course because there is so much energy release there is so much directional release, from a relative sphere and how the points would separate as distance increases, even a perfect sphere must be composed of ultimately a finite quantity of points, and these points then extended away from the sphere surface in all their finite point directions, will prove over space and time to have increasing distance between them? Quite the interesting seeming fact.

No. The observation of quantized electromagnetic fields occurs in lab experiments regardless of the source of photons, astronomical or otherwise. All astrophysics observations show the same property no matter what you're looking at, star, galaxy, nebula, white dwarf, neutron star, whatever (all have very different astronomical behaviors).

All theory and experiment shows it's fundamental physics.

originally posted by: HODOSKE
The electron changing from a particle to a wave just by us looking or observing it always fascinated me. Does that mean our mind changes matter ?

No. Detector devices which don't think do the same thing. The electron was always a particle and wave simultaneously.

Our thinking can create or change the universe? And if observing things can change their physical properties, does that mean our minds are really powerful or maybe our concept of reality is not what we think ?

I am not a fan at all of those notions. I call them 'quantum woo'.

Sometimes I feel there is nothing we can scientifically prove because reality may not be what we think it is.

Science shows what's reliably consistent and justified by experimental data known so far. With fundamental physics, that has been exceptionally accurate and predictive. It's not mathematical proof, but it's better than anything else humans do.

originally posted by: Arbitrageur
Nature is the way it is. If you want to claim that electricity and magnetism are completely symmetrical, I find it a weak claim if you can't find magnetic pole carriers as we find charge carriers:

Isnt the magnetic pole carrier the charge carriers?

Is what you are saying 'there are two aspects to magnetic pole and how it relates to pole carrier; and there is only one aspect to electric pole and hot it relates to electric nature'?

An electron moves;

Electricity is the fact that when the electron moves the EM field the electron is coupled to, moves, and thus if other electrons are in the area they will move, and if you scale up with a material with a bunch of electrons that are orientated in a particular manner move in a particular way, the phenomenon of electricity is said to exist.

An electron moves;

Magnetism is the fact that when the electron moves the EM field the electron is coupled to, moves, and thus if other electrons are in the area they will move, and if you scale up with a material with a bunch of electrons that are orientated in a particular manner move in a particular way the phenomenon of magnetism is said to exist.

originally posted by: ImaFungi
a reply to: pfishy

Those were separate questions, not meant to be related. Merely two fundamental questions I have been seeking the deepest insight too for the past few years, which I have been doing so because I know that know human truly comprehends the true fundamental truth of these insights. I brought them up to by pass your insulting belief in the need to start from the conditions which you felt we needed to agree on, to assume I am so far below you in understanding that we need to start from positions which are taught to 13 year olds.

The first question was regarding the fundamental nature of gravity.

The second question was regarding the fundamental nature of light.

Lets you and I focus on light, since if you will read this thread you will see more recently I attempted to dig as deep as possible into gravity with a lengthy series of questions.

As for light, I am wondering about the supposed particle nature, the meaning of masslessness, how it is related to if not entirely actually the phenomenon of electro magnetism itself in every way. And, in what physical form light exists in before it is propagated. Which requires the intimate romance with the ultimate axiom of something and nothing, to avoid cheating, by cheating I mean lying to oneself, by lying to oneself I mean being wrong, I mean being ignorant. Such as to say 'a photon actually exists, and then when it enters into a lattice the photon which is not nothing, 'disappears' and becomes 'energy' which is not nothing, but could sort of be nothing, in the sense that 'movement' is 'real' but not something'. I can further expand upon all this if you dont fully grasp any aspect of what I have just said.

Well, the photon begins as an elevated charge in an electron. As the electron, which is compelled in the majority of circumstances to seek the lowest energy level, drops to a lower energy state, the excess energy can be released as a photon. It is a charge before it is a photon. Thus constantly remaining something. It is a quanta of energy in the electron, and a waveform outside of it, which collapses becomes a point particle upon certain interactions.
As for the lack of mass and what governs that, I do not know. I'm no physicist. But, light is certainly not baryonic matter, thus it does not interact with the Higgs Field. And I would be lying if I told you I know how leptons attain mass. But again, it is not a lepton, either.

originally posted by: ImaFungi

originally posted by: Phantom423
a reply to: ImaFungi

I understand - I just picked up on that one scenario where the object is at rest with no mass or applied force.

So if the object is at rest, the object is an inertial reference frame with no reference i.e. no outside force or reference to act on it. So F = ma where F and a are usually vector quantities, and F = mg where g is acceleration due to gravity are meaningless. So gravity has to = 0. It takes two to tango to have gravity - can't think of any other scenario for an isolated object in an adiabatic system with 0 references. Even if there was an isolated photon which has no mass, there would be some interaction to induce some small gravitational effect (I think). But in a world consisting of a single object, I think gravity has to = 0.

Well is it not that the only way in which an object exists at all (especially as in my example I was using a perfectly spherical earth sized object, referring to it as, planet) is due to what is termed 'gravity'? So that planet cannot exist and there exist 'no gravity', right?

Also, the way in which gravity exists, is due to the material medium which surrounds objects/other material/other material mediums/other styles of mass;

So yes I recall in one train of thought I expressed the hypothetically scenario of taking what we know of as matter/mass/planet and placing it in a hypothetical realm in which it was the only 'something' that existed amidst an area of absolute nothingness;

But the related train of thought, was the planet, existing far away from galaxies, though in this universal system of universe;

To posit the stationary planet, existing amidst the gravity material medium. And different trialed motive versions therein.

Ok, would it be fair to replace the earth-sized sphere is this question with the actual Earth? Because if so, it's gravity is acting upon itself (in the hypothetical universe where only it exists). Otherwise, the continental plates and oceans would drift off the surface, followed by the liquid parts of the mantle, then the rest of the stony parts, and the liquid outer core.
And it does seem to me that the faster the planet moves and/or rotates, the greater it's gravitational strength would be, due to the increased energy. Though I believe the difference between absolutely 0 inertia and what it (the Earth) has now would cause the difference to be negligible. You would only really see a noticeable difference if the planet were moving/rotating as speeds approaching, say, 7-10% of C or greater.

a reply to: mbkennel

Quantum woo im so using that with my students.

originally posted by: dragonridr
Quantum woo im so using that with my students.

RationalWiki has a good article by that title, which is summed up in three statements pointing out the appeal to woomasters:

rationalwiki.org...

The logical process runs something like this:

1. I want magic to exist.
2. I don't understand quantum.
3. Therefore, quantum could mean magic exists.

It's a problem because the claims sound scientific to non-scientists, but of course they are either based on very shoddy "science" or no science at all in some cases, like when "what the bleep do we know" shows you the double slit experiment one minute and is talking about the spirits of 17,000 year old Lemurian warriors the next, as if this all has something to do with quantum mechanics.

My hypothesis is that science has dealt serious blows to traditional religions, so more people are searching for more scientifically compatible religions to replace the traditional religions, like the quantum woo beliefs or the "aliens will save us from ourselves" type beliefs.