Concerning the double slit experiment

Mar 23, 2022
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I just read the latest article about this, but I thought this apparent paradox had been answered:
Light travels as a wave, but interacts as a particle.
 
Mar 23, 2022
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Yes, nature sometimes gives us exactly what we're looking for :) I don't recall the exact source for my comment, but I do feel "Light travels as a wave, but interacts as a particle" is an apt description of light. It explains the double slit paradox better than anything else I've come across.
 
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Catastrophe

"There never was a good war, or a bad peace."
"Light travels as a wave, but interacts as a particle" is an apt description of light.

We: "Light, what are you?"

Light: "You would not understand if I told you", <Shrugs> "Stop trying to constrain me into silly little verbal boxes! I am brighter than that!"

"Relayed by" . . . . . . . . .

With apologies. Light can be a little fractious sometimes ;)

Cat ;)
 
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Feb 7, 2022
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Our problem with understanding light is that the things we really experience in our macro world that are waves need a medium to travel through. But, when we tried to find how fast the earth is traveling through the presumed medium for light (dubbed the "ether") we found that we could not measure and difference in any direction, even comparing measurements in different seasons, when we were in opposite positions in our orbit around the sun. So, rather than assume we were somehow in the middle of the universe with the sun revolving round us, we came up with the Special Relativity Theory.

That leaves us with the presumption that light "waves" travel through nothing in empty space. But, the way we understand "waves" that we can see are waves is that they are cyclic perturbations of the positions of matter that transmit energy from one location to anther location. Light waves also transmit energy from one position in space to another, but appear to us to do so without displacing any material medium.

So, we really do not understand how that is done, physically. We can describe it with mathematics, but that is not the same as really understanding light waves in the same manner that we understand waves in the ocean. Getting unexpected, and unexplainable results from experiments with light are just a confirmation that we are not good at predicting what light can actually do, because we do not have a full understanding of how it works.
 

Catastrophe

"There never was a good war, or a bad peace."
"we 'really' do not understand how that is done, physically. We can describe it with mathematics, but that is not the same as really understanding . . . . . . "

Reminiscent of Newton and Gravity.
 
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Our problem with understanding light is that the things we really experience in our macro world that are waves need a medium to travel through. But, when we tried to find how fast the earth is traveling through the presumed medium for light (dubbed the "ether") we found that we could not measure and difference in any direction, even comparing measurements in different seasons, when we were in opposite positions in our orbit around the sun.
Nicely stated. Einstein himself never said this was proof the either did not exist, only that light was independent of it. [I think I'm right on this.]

So, rather than assume we were somehow in the middle of the universe with the sun revolving round us, we came up with the Special Relativity Theory.
Interestingly, the modified Tychonic model is the one geocentric model that would work.

Getting unexpected, and unexplainable results from experiments with light are just a confirmation that we are not good at predicting what light can actually do, because we do not have a full understanding of how it works.
It seems clear we don't understand it's weird behavior, but are you suggesting we aren't good at predicting how light will behave? [I won't be surprised if you're right, but I'm curious about this.]
 
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Feb 7, 2022
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Well, we do have the ability to predict with high accuracy how gravity works here and now.

But, our observations of how the stars are moving in other galaxies, and apparently in our own, don't seem to match what we think we see as mass and what we predict about gravity. So, is that an indication that there is matter we don't see, i.e., "dark matter", or maybe that we are not accurately calculating the relativistic frame dragging of space by the rotating matter, or what?

And, when we start trying to think about how gravity would work if the whole universe was just at tiny ball of energy, with no matter able to form at the high "temperature", are we really sure about that?

Regarding Helio's question about being sure about how light would behave: Again, we seem to have pretty good mathematical models for most macro observations. But, we need to choose between 2 different models to make calculations match observations (waves or particles). We know by experience which works for things that we have already observed. But, how do we know for things we have not been able to directly observe?

Here's a question in my mind that somebody may already have an answer for: Would two blobs of light energy have a gravitational attraction for each other? We know that they would respond to the gravitational attraction of matter, but that is described by General Relativity as photons traveling through space warped by the mass of the matter. So, a parallel question would be whether light in sufficient density can also warp space. Light has "mass" in the sense that it can impart momentum transfer by absorption or reflection, but it has no "rest" mass in our models. So, can enough light warp space? Can light "frame drag" space in huge cosmological or tiny sub-atomic scales?

BTW, is space really nothing, i.e., empty vacuum? How do you warp a vacuum? Yes, I know that some people think of "the vacuum of space" as a region that has no matter, but is filled with energy fields. But, then energy fields are not "nothing" and are even calculated to exert forces on matter and even the "framework" of space. So, our language makes us communicate in what are basically analogies to what we have experienced in our local, macro world, and that seems to be less than adequate for comprehending things on cosmological and subatomic scales.
 
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Nov 19, 2021
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Matter and energy are not conserved but mass is. When matter is converted to energy, the energy has the same mass as the matter had. So, yes, light beams would attract each other. The practical problem is that a tiny bit of matter turns into an enormous amount of energy. The fireball from a 1 megaton atomic bomb represents only 1 kilogram of matter being converted into energy. Two light beams would hardly interact since their mass density is so low.
 
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Feb 7, 2022
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Matter and energy are not conserved but mass is. When matter is converted to energy, the energy has the same mass as the matter had. So, yes, light beams would attract each other. The practical problem is that a tiny bit of matter turns into an enormous amount of energy. The fireball from a 1 megaton atomic bomb represents only 1 kilogram of matter being converted into energy. Two light beams would hardly interact since their mass density is so low.
True enough for the amount of mass converted to energy in the practical experience of those of us observing things now, here on earth.

But, when we extrapolate back to the "beginning" of the Big Bang, then all of what is now matter would have been energy of some sort. At some point (before 10^12 second), not even photons, yet. But, gravity is presumed to have existed back into the Planck epoch (<10^-43 second). See https://en.wikipedia.org/wiki/Chronology_of_the_universe . After about 10 seconds, the universe is calculated to be about 300 light years in radius, with protons, neutrons and electrons, plus a massive (pun intended) amount of photons. Density of matter is calculated to be "on the order of 4 grams per m^3 (about 0.3% of sea level air density)." A bit of calculation on my part shows that is far less radius than an event horizon radius for that much included mass, so not even the mass of the light should have been able to escape through space. Hence the need for postulating that space itself expanded to increase that radius and decrease the density of matter in the universe, despite gravity. In fact, even with that, the observed universe still calculates out to be a black hole.

But, we don't know how space can inflate. So, do we really know what light can "do" to space?
 
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Catastrophe

"There never was a good war, or a bad peace."
"gravity is presumed to have existed back into the Planck epoch (<10^-43 second"

I particularly liked this assumption.

Also: "when we extrapolate back to the "beginning" of the Big Bang"

Great. BBT seems to work well, with a few unjustified assumptions. Newton's Laws still work well, even though he didn't understand gravity.

Like Newton, BBT has to shift over when a new Einstein improves matters around t = 0.

Cat :)
 
Feb 7, 2022
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This Is Why Our Universe Didn’t Collapse Into A Black Hole | by Ethan Siegel | Starts With A Bang! | Medium

This explains it very well. The equations for a black hole are for a static assembly of mass, not a hot expanding mass. There was enough energy in the expanding fireball to stay ahead of its gravity and avoid collapsing.
Bill, I disagree that the link you posted explains anything. All it does is introduce a "Goldilocks factor" that the universe was already expanding instead of being static when it was created. Just another added "free parameter" to "make things work" for that model. And, worse, it claims that the probability that this universe would exist is 10^-24. No idea how anybody calculated that, given that the empirical data is 10^0 = 1. That sure is some "whiz-bang" theory (pun intended).

Seriously, the best I can understand this is that they are claiming an initial momentum factor for the mass value, that somehow is applied to space itself, rather than pushing mass through space. Since all of the mass would have been energy to begin with, and not even light in the very early instants, this all seems extremely speculative.

It isn't really an explanation at all; it is another example of saying "You can't prove the theory is wrong because we added another free parameter that nobody knows anything about, so nobody can prove that parameter is not correctly quantified, ergo, nobody can prove the theory isn't true." But, it isn't for others to prove that scientists have it wrong, it is for scientists to prove that they have it right. Which seems a long way from happening, so far.

Interestingly, your link goes through the explanation of how Newton's gravity model did not fit the observations of Mercury's orbit, and that using Special Relativity got results closer to the observations, but it was not until General Relativity was developed that we could match the observations for Mercury. So, now that we know that we don't match the observations for stars orbiting in galaxies, maybe that process needs to be extended to yet another insight, rather than imaging that there is enough invisible mass to make the General Relativity model work.

And, frankly, it is so hard to actually calculate the full General Relativity solution for a galaxy that I wonder if we just have not yet properly accounted for frame dragging. There is an ongoing argument between people who claim to have demonstrated that frame dragging can account for observed orbits, and others who claim it must be bunk. But, everybody is making simplifying assumptions.

By the way, apparently Hubble has just documented a free traveling black hole in our arm of our galaxy. See https://petapixel.com/2022/06/10/hubble-records-mass-and-location-of-a-black-hole-for-the-first-time-ever/ . So, at least there are a few solar masses that are definitely "dark".
 
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Catastrophe

"There never was a good war, or a bad peace."
Unc,

Does that mean that an assumption
"another added "free parameter" to "make things work"
was necessary?

I must say that I found it amazing that one proton either way would make all the difference. Or have I misunderstood something?

So is anything safe from the magic of "starting assumptions" (subject to ad hoc "tuning"), which ensure the desired result?

Cat :)
 
Nov 19, 2021
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The post explains how the universe was created, whether you accept it or not is a different issue. You are free to come up with your own explanation. Note that there should be no concern whatsoever that our universe is made possible by a 1 part in 10^24 bit of matter. There could well have been 10^24 universes that did not have that particular recipe and they all failed. We just don't know. All we know is that ours worked out. Until you come up with a better mode,l and it gains more acceptance in the scientific community, I'm going with this one.
 
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Catastrophe

"There never was a good war, or a bad peace."
If a model works, I am happy to go with it. If it needs assumptions or 'fine tuning' I will accept these on a "for the time being" basis, so long as I understand them, and their use of them.

My real concern is with t = 0. I am worried about curves that are asymptotic to the vertical axis as they approach x = 0. When they breakdown, and physics is accepted as not being applicable, that worries me. The use of the curve itself worries me, unless there a break point where it is accepted that the curve is not applying - as with the graph in the article quoted, where dark matter "takes over". There needs to be a reason. Near enough is not good enough. I am retired, and never was a professional astrophysicist, so I have no axe to grind.

I am especially worried about extrapolations, especially when they involve different gradients, vide "inflation", but that is another matter.

Cat :)
 
Nov 19, 2021
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Our physics breaks down before 10^-43 second which is why we can't explain what happened earlier. That does not mean the Big Bang didn't happen.

Inflation is required to explain current observations, that we can't explain what caused inflation does not mean it did not happen.

We see effects consistent with the presence of Dark Matter so we assume it is there even though we can't see it. We are simply stairstepping towards a better explanation.
 
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Catastrophe

"There never was a good war, or a bad peace."
I should have made it clear.
"The post explains how the universe was created"
No. It explains what happened starting from a tiny fraction of a second after what we are all describing as "t = 0".
As you correctly state :) I can choose my own path, as this is metaphysics and no longer science. I accept all the good matches, just as I accept all Newtonian physics where they are applicable, with the reservation that I know that they become subservient to Einstein as one approaches c.
I do not mean to antagonise you in any way. I do understand and respect your position.

Cat :) :) :)
 

Catastrophe

"There never was a good war, or a bad peace."
Our physics breaks down before 10^-43 second which is why we can't explain what happened earlier. That does not mean the Big Bang didn't happen.

Inflation is required to explain current observations, that we can't explain what caused inflation does not mean it did not happen.

We see effects consistent with the presence of Dark Matter so we assume it is there even though we can't see it. We are simply stairstepping towards a better explanation.
Yes, that is fine. It actually overlapped with mine, as it arrived during the time I was composing my previous post.

I thoroughly respect that position. It is the best we have, until something better, more consistent with observation comes along - which may never happen. You are concerned above all with the science, and there is nothing wrong with that. I go along with the best available science (as do you) but I am also intrigued with the metaphysics. Mea culpa.

Cat :)
 

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