space is expanding,,, wait what??

[tsmspace]

On 8/3/2019 at 6:39 AM, wasab said:

I remember my 5th grade science teacher taught me that light is not matter. It doesn't take up space so it can't be particle and shouldn't have any mass. 

this is a good one for me to reply to, since the subject is so broad. 

 

the following is the view of myself only, and I do not claim it to be accepted physics,, ,instead this is merely a statement of my position and how I understand the world. :::::

 

light is NOT a wave, it is ONLY a particle. the wave particle duality will exist for a period of time as a scientific concept while certain other important questions remain unproven. (tongue twister...)

 

no the following cannot be used in a specific debate,,,,,, but a photon is so incredibly small, that although the physics of the particle is not different from larger masses, the realized energy values are so extreme, that they are off the scale in every direction. We simply don't have the resolution. (but wait, can't you just move the decimal place more times?? ,, right, so this is not a useful statement for a publication). No two photons are identical. like snowflakes, they are truly unique in every way,,,, however, they have a window of possible sizes and speeds they can exist at. Also important, is light does not have a provable frequency until it hits something. No one is watching photons vibrate. They are soaking them up into voltages or film, and interpreting the result. A photon can't possibly be any larger, because it would take too much energy to release a larger one. The energy transfers that occur at the atomic level and result in photon release simply don't have the energy it takes to release a larger particle at the speed of light. Once a particle is large ENOUGH, it doesn't need to travel so fast to escape the atom that releases it. Light is so fast, because if it is travelling any slower than that, it won't be released. It will simply not escape. If a photon drops below the speed of light at any time during its course, it is captured. Light does not travel faster than the speed of light, because as soon as there is enough energy to release the photon, it releases, which occurs at the speed of light. It IS imaginable to release particles at greater than the speed of light under certain conditions, but the extreme amount of energy it takes is exponentially greater than the energy it takes to release a photon at the speed of light, and only very rarely are the conditions available to keep the particles where they are when they have so much energy. 

 

 

------- one problem is the double slit experiment and shrodingers cat. That problem is flat out stupidity. The community declares that observing the photon changes its behavior, but CANNOT POSSIBLY offer evidence of this. Instead, they put an instrument that produces Electro-Magnetic Interference in the way of the photon, power it on so that it produces an energy field that the photon will fly through, then completely ignore that the photon is flying through said electric field when they claim it was "watching" the photon that changed its course. 

 

No. sorry. If the cat is alive, its alive and if its dead its dead. That analogy was invented when people said things that if repeated today, you might actually be killed on the spot. the photon passing through the slit is not passing through a consistent environment when all that's used is film to see the pattern. They will be bouncing off of all kinds of matter and energy that we can't control at such a small scale, so the photons will occupy every possible place they can imaginably occupy if the beam is left on for a while. Once there is an electric field in the way, the environment the photon BEAM will pass through is much more consistent, as the magnetic fields will hold all of the energy and matter within it in place. 

 

Somehow,,,, people ..... just./........ what are they thinking about. 

[tsmspace]

On 7/30/2019 at 11:16 PM, RuffRuffmcgruff said:

yes we need to talk about that one. 

[harryk]

3 hours ago, tsmspace said:

light is NOT a wave, it is ONLY a particle. the wave particle duality will exist for a period of time as a scientific concept while certain other important questions remain unproven. (tongue twister...)

I have one question for you. If light is not a wave then explain the interference pattern seen with the double slit experiment? 

 

 

 

 

[TempestCatto]

This is a Gavin Free esque question, lol. But the real answer to your question is that God just keeps downloading more RAM, which keeps the universe buttery smooth during expansion.

[tikker]

17 hours ago, tsmspace said:

the following is the view of myself only, and I do not claim it to be accepted physics,, ,instead this is merely a statement of my position and how I understand the world. :::::

...

light is NOT a wave, it is ONLY a particle.

It's good to be sceptical and try to form your own view of things, that's what science is about

 

You have formed a hypothesis: a photon is a particle. If a photon is a particle, we should think: what does that make light? A very fundamental question. You could imagine it as particles. A particle has an energy and a wave of particles could be assigned a frequency of sorts. The photo-electric effect supports the idea that light indeed consists of particles. in other cases, we clearly observe it to behave like a wave though:

14 hours ago, harryk said:

I have one question for you. If light is not a wave then explain the interference pattern seen with the double slit experiment?

Therefore we should reject the hypothesis that light is purely a particle, as a particle is not a wave. The double slit experiment, on the other hand, excludes light being (a) particle(s), as that would give a different pattern. At this point we appear to have a problem: both a pure particle nature and a pure wave nature are disproven at the same time. This is where the wave-particle duality comes in. It is a way of accepting, however counterintuitive, that there are things that we cannot explain as being one or the other, but have to be a combination of both.

 

17 hours ago, tsmspace said:

No. sorry. If the cat is alive, its alive and if its dead its dead.

Correct. Schrödinger's cat is a thought experiment meant to illustrate a concept in quantum mechanics: a superposition of states. The thing is, quantum mechanics is weird and does not scale to the scales of cats, on which we typically observe our world. It only works on tiny scales and can also change, depending on your favorite interpretation of quantum mechanics.

 

17 hours ago, tsmspace said:

It IS imaginable to release particles at greater than the speed of light under certain conditions, but the extreme amount of energy it takes is exponentially greater than the energy it takes to release a photon at the speed of light, and only very rarely are the conditions available to keep the particles where they are when they have so much energy.

In the current framework of our physics, it would take an infinite amount of energy to accelerate anything with a non-zero rest mass to light speed, let alone beyond. This means photons have to have zero rest mass. Having zero mass implies, it takes zero energy to accelerate them, however, so the "solution" is that they "just" travel at light speed (by definition).

 

In the end, we only have theories and are making observations trying to disprove those theories. As long as a theory holds some predicitive power and we do not observe contradictory objects or events, then we can consider it to be the best description of reality that we have at that point. If we were to observe something moving faster than the speed of light, we'd have to change physics as we know it, because of one simple, but extremely important axiom: the speed of light is constant.

 

The thing with axioms is that they are something you take to be true, without proof, which at some point you have to do.

[tsmspace]

On 8/4/2019 at 5:22 PM, harryk said:

I have one question for you. If light is not a wave then explain the interference pattern seen with the double slit experiment? 

 

 

 

 

Well, the slit is not a perfectly stable evnironment, and the photons are not perfectly identical.

[tsmspace]

10 hours ago, tikker said:

 

 

Correct. Schrödinger's cat is a thought experiment meant to illustrate a concept in quantum mechanics: a superposition of states. The thing is, quantum mechanics is weird and does not scale to the scales of cats, on which we typically observe our world. It only works on tiny scales and can also change, depending on your favorite interpretation of quantum mechanics.

 

 

Well, what you mean is, quantum predictions dont scale to observable size. 

[tikker]

11 hours ago, tsmspace said:

Well, what you mean is, quantum predictions dont scale to observable size. 

I meant that (most) quantum effects do not manifest themselves on human scales. It has been seen on molecular scales though: https://www.nature.com/articles/44348 and you could say superconductivity or superfluidity is a macro manifestation of quantum mechanical effects.

[wasab]

23 hours ago, tikker said:

Having zero mass implies, it takes zero energy to accelerate them, however, so the "solution" is that they "just" travel at light speed (by definition).

 

 

But I thought light travels slower in water? And you can theoretically make light travel slowly to the point it barely moves at all. 

[wasab]

13 hours ago, tsmspace said:

Well, what you mean is, quantum predictions dont scale to observable size. 

I can only imagine light as an electromagnetic wave. I mean thats what classical eletricity and magnetism and all its fancy equations taught me in college.

 

I never studied modern physics(Einstein relativity) but from what I heard, it makes little sense. 

[tikker]

10 minutes ago, wasab said:

But I thought light travels slower in water? And you can theoretically make light travel slowly to the point it barely moves at all. 

Effectively it travels slower, because it interacts with the medium. Light itself still travels at c however.

 

5 minutes ago, wasab said:

I can only imagine light as an electro-magnetic wave. I mean thats what classical eletricity and magnetism and all its fancy equations taught me in college.

 

I never studied modern physics(Einstein relativity) but from what I heard, it makes little sense. 

Classical theory still works very well for everyday stuff. There's a reason they're still around and taught Relativity and QM become important once you approach relativistic speeds (i.e. a significant fraction of the speed of light) and tiny scales, respectively.

https://en.wikipedia.org/wiki/Classical_mechanics#/media/File:Physicsdomains.svg

 

[dalekphalm]

22 minutes ago, wasab said:

But I thought light travels slower in water? And you can theoretically make light travel slowly to the point it barely moves at all. 

It does travel slower in water.

 

What we think of as "The speed of light", is more accurately described as "The speed of light in a vacuum" - which is:

299,792,458 m/s (some 670 million miles per hour)

 

However, the medium through which light travels, most definitely affects the speed, because light interacts with that medium (whatever it is), and it slows down.

 

Scientists have slowed light down to about 17 m/s (38 mph) by passing it through densely packed, super cold Sodium Atoms:

https://news.harvard.edu/gazette/story/1999/02/physicists-slow-speed-of-light/

 

In a different experiment, Scientists were even able to actually stop light:

https://news.harvard.edu/gazette/story/2001/01/researchers-now-able-to-stop-restart-light/

[wasab]

2 hours ago, dalekphalm said:

 

I just wish to know if light is matter or not ..... Or maybe it's its own thing? 

[dalekphalm]

3 minutes ago, wasab said:

I just wish to know if light is matter or not ..... Or maybe it's its own thing? 

As far as we know, light is not matter, because matter has mass, and light (as far as we're aware) has no mass.

 

The simple truth is we don't really know what light is, fundamentally. We know a lot about how it works, but I suspect it's something else.

[tikker]

1 hour ago, wasab said:

I just wish to know if light is matter or not ..... Or maybe it's its own thing? 

It's not matter, what it is, we don't really know. That's why we're inventing all these crazy (in a good way) theories like quantum field theory and the likes, in order to try and explain things. These quickly become  abstract and difficult to grasp introducing "fields" and particles as "realizations/excitations of those fields" (not saying that as a "look at me I'm so clever", I don't really grasp QFT either ).

[harryk]

3 hours ago, wasab said:

I just wish to know if light is matter or not ..... Or maybe it's its own thing? 

Light is light. It is one of the fundamental mass-energy components of the universe. The total makeup of the today's universe being:

 

-  72% Dark Energy

-  23% Dark Matter

-    4% Matter

-  <1% Photons

 

We define things by our ability to mathematically describe them and how they behave. Light is formally called electro-magnetic radiation because it can be mathematically described as a coupling of an electric field wave and magnetic field wave; because of wave-particle duality light can also be described as photons. Matter is defined as anything that has mass (is affected by gravity) and takes up space (we cannot put two particles in the same spot). Then there is Dark Matter and Dark Energy. These names are essentially placeholders because we don't know what it is. We know it exists because we can see its affects on the matter in the universe but we can't see it or detect it directly thus it's "dark". 

[tsmspace]

Ok I don't want to quote a billion, but on the double slit experiment:::: 

 

 

uh, that's not what's happening. What's happening, is on the photonic scale, the slit is HUGE. so, if a photon goes blasting down the middle of the slit, it will just shoot straight down and make the primary bright center. BUT,,, if the photon passes particularly close to one side of the slit or another, the path of the light will be refracted by the "energy" of the material it is close to. We can actually SEE the same phenomenon by looking closely at an object, such as our finger, and noticing the warping of the scene behind it. 

 

the waves aren't ...  interacting  ... the way the pond waves are. one photon is being refracted at a time. If you made a dot, instead of a slit, you would find a larger dot inside the box, with similar coloration. in that case, the refraction would be more omnidirectional,, but with a slit, you end up with a lot of the light going to one side or the other. 

 

two slits might have more to do with the colors instead of just white light, but I guess I don't really know. 

 

In other words, ---- I don't really understand that experiment and where people are coming up with wave particle duality. 

 

 

[harryk]

8 hours ago, tsmspace said:

uh, that's not what's happening. What's happening, is on the photonic scale, the slit is HUGE. so, if a photon goes blasting down the middle of the slit, it will just shoot straight down and make the primary bright center. BUT,,, if the photon passes particularly close to one side of the slit or another, the path of the light will be refracted by the "energy" of the material it is close to. We can actually SEE the same phenomenon by looking closely at an object, such as our finger, and noticing the warping of the scene behind it.

This is called diffraction. Any time a photon passes very close to an edge it's trajectory will be bent slightly. The exact amount of bending is very predictable and depends on the wavelength or energy of the photon. That's why in the Veritasium video they saw colors because he was using sunlight; the colors separate because they diffract at different angles. To make things simpler I'm going to stick with monochromatic light for the following explanation. 

 

If I shine some light at a single slit, some of the photons going through the slit will be diffracted making the resulting image on the screen to the right a spread out gradient (not actually true but more not this later). 

 

 

If I add a second slit, my expectation would be that the second slit would act the same as the first and the resulting image would be like adding two gradients on top of each other. If light acted purely like particles this would make sense. Note that color in the diagram is purely for illustrative purpose, all light in this experiment is the same color/wavelength.

 

 

But if I do this IRL this is not what I see. What I see is segments of bright separated by segments of dark.

 

 

This can be explained if light behaves as a wave. What I am seeing is constructive and destructive wave interference. If the two light waves hit the screen when they are both at a peak, they add together, there is constructive interference and the resulting image is bright. 

 

 

At a slightly different position on the screen the two light waves hit when one is at a trough and one is at a peak. Add them together and the result is nothing. They cancel each other out. This is destructive interference and the resulting image is dark. This is because the distance the lower light wave has to travel is exactly one half wavelength longer. If you repeat the trajectory of waves for every position on the screen you will end up with patterns of bright and dark, an interference pattern.  

 

 

This is the important revelation from the double slit experiment. It has nothing to do with light interacting with the slits, it's all about the difference in path length from each slit to the screen and the resulting summation of the light waves at that position. I can change the separation of segments in the interference pattern by changing the distance between the two slits. It's all determined by geometry. 

 

Back to my comment earlier about the single slit. Light diffracts independently at each edge.  A single slit has two edges thus it behaves like the double slit and will produce an interference pattern. So will a small pinhole, it will produce an airy disk. 

[tikker]

13 hours ago, tsmspace said:

In other words, ---- I don't really understand that experiment and where people are coming up with wave particle duality.

Note that light is not a particle and light is not a wave. It is neither.The term wave-particle duality was coined, because:

1. the double slit experiment shows you that light behaves like a wave, because of the interference patterns that are seen and are predicted by describing light as a wave*. A particle nature, as Veritasium and @harryk say, would produce just two bars of light, not an interference pattern.
2. the photo-electric effect shows you that light could be like a stream of particles, because light with too low an intensity (i.e. too little energy per "particle") will never knock free electrons.

Notice the emphasis on "like a". In different circumstances, different descriptions are needed. This makes it intrinsically neither 100% of each. I like this excerpt that was apparently written by Einstein in a review of physics:

Quote

It seems as though we must use sometimes the one theory and sometimes the other, while at times we may use either. We are faced with a new kind of difficulty. We have two contradictory pictures of reality; separately neither of them fully explains the phenomena of light, but together they do.

It's also worth noting that wave properties are a quite natural consequence in quantum mechanics, as it's all (or mostly) based on wave functions and probabilities, e.g. a particle is not at  (x, y, z), but it has a probability P(x, y, z) to be at that position so to say.

 

*(A single photon has also been seen to behave wave-like https://physicsworld.com/a/the-secret-lives-of-photons-revealed/)

 

I personally think wave-like properties are hard to imagine for us, because the only waves that we are truly familiar with, are gravity waves: the ones you see on the ocean. The problem comes when the molecules (particles) that make up water become "fields" and the "wave" becomes an objects nature rather than being composed of those objects.

 

To bring it back to the original point again, that's also why I think it's difficult to imagine space expanding. The fabric of space-time itself is expanding and aside from combining time and space, also is a 4-dimensional something. We can't truly comprehend or visualize that. The book/movie Flatland is a great watch about this.

[tsmspace]

11 hours ago, harryk said:

If I shine some light at a single slit, some of the photons going through the slit will be diffracted making the resulting image on the screen to the right a spread out gradient (not actually true but more not this later). 

 

right so talking about it, just a question that might be interesting.

 

therefore the dark spots between the bars of light are still being hit by as many photons as they would be with only one slit (well, maybe doubleish),,, so although there is no visible light there is energy??? 

 

or not?? 

[tsmspace]

secondly, try as I might I don't find an example where i can see plainly that they are sending one photon, despite how many times people talk about single-particle experiments. I just dont' see where they are sending and displaying the effects of a single particle. 

 

anyway, the suggestion of the dead cat, is that the particles are actually occupying all of the space of the diffraction until they actually hit. (which I have to admit sounds like malarky to me). 

 

assuming a constant beam of particles, I can understand the "bose noise cancelling effect", assuming the photons are still actually hitting the dark spots but not producing a visible effect. that doesn't really look like what's happening, because of the way the lines of visible light appear to be diffusing anyway. 

[mr moose]

When topics get complicated I tend to think of this:

 

 

The trick is understanding the scale, because until we know how much there is out there that we don't know we can put a value on it.

[harryk]

10 hours ago, tsmspace said:

therefore the dark spots between the bars of light are still being hit by as many photons as they would be with only one slit (well, maybe doubleish),,, so although there is no visible light there is energy??? 

Absolutely that would make sense. But as I'll show below, that's not the case. 

10 hours ago, tsmspace said:

secondly, try as I might I don't find an example where i can see plainly that they are sending one photon, despite how many times people talk about single-particle experiments. I just dont' see where they are sending and displaying the effects of a single particle.

Back in the early 1800's when Young first performed the double slit experiment he was restricted to using sunlight or candlelight, but technology advances and it the early 1900's it became possible to produce a single photon at a time and once again perform the double slit experiment. The setup is exactly the same but now I have a controllable light source which can emit one photon at a time and for the detector let's say I'm using film. 

 

I send one photon through the slits, remove the film and develop it. I will see one dot and it will appear randomly anywhere on the film.

 

I put in a new piece of film and send ten photons through. Still one at a time, waiting in-between each. This time I see ten dots, which again appear randomly placed anywhere on the film.

 

I do it again, this time sending a hundred photons through. Again the dots seem randomly distributed.

 

Once more, this time one thousand photons. Still only sending one at a time. Now I start to see a pattern. It appears to be the same light and dark interference pattern as before.

 

 

This is absolutely baffling. How can single photons be interfering with each other when they don't exist at the same time?

 

Thus is born the science of quantum mechanics. It doesn't matter how or when the photons are sent through the slits, all quantum mechanics cares about is the beginning and end. I can send a thousand photons through one at a time or all together. As long as I don't interrupt the process the end result is the same. You can justify this however you want; again quantum mechanics doesn't care what happens in the middle.

 

Personally I like to think of it as each individual photon has a certain probability of landing anywhere on the film. A higher chance at the bright spots, lower at the dark spots. If I send a single photon through, there is a non-zero chance that it can appear anywhere on the film. The only way to prove that some areas have a higher probability is to repeat the experiment many times, aka send many photons through.

 

This is the same idea as Schrödinger's cat. I put a cat in a box with a bomb that has exactly a 50% chance of going off in the next minute and close the box. Wait one minute. Until I open the box I do not know if the cat is dead or not. Similarly quantum mechanics does not care until I open the box and confirm the answer. Thus the idea that the cat is simultaneously dead and alive. Same thing with the photons. Each photon may or may not have interacted with the other photons. We don't know until we look.

 

[tikker]

12 hours ago, tsmspace said:

assuming a constant beam of particles, I can understand the "bose noise cancelling effect", assuming the photons are still actually hitting the dark spots but not producing a visible effect. that doesn't really look like what's happening, because of the way the lines of visible light appear to be diffusing anyway. 

They diffuse because it's a continuous distribution instead of a discrete effect. It's not that a photon can be at A, but not 1 cm away from A. It is more likely to be at A than to be 1 cm away from A. So send a thousand photons through your slit, and more will land on the areas where they are more probable to be. The above illustration shows that there are idneed still photons landing at those spots, they just have a lower probability of being where the dark spots form, so the intensity is less (intensity is proportional to the number of photons).