Existence

No, they actually experienced different amounts of time. GR affects time, not clocks. We know this because we can measure the effects of GR time dilation on things that aren't clocks.I.e. the Twin Paradox - you and your twin brother have by definition the same age. He heads off on a near-lightspeed journey to Alpha Centauri and back. As your brother buzzes the control tower at constant near-lightspeed on the way out, you look in the ship's window and he looks out. You spot his ship clock ticking slower than yours. He sees your tower clock ticking slower than his. You're both right relative to your own frame of reference. You age 10 years waiting for his return; he ages only 2 during the trip. It's not because GR added a bunch of extra days to his calendar, it's because you're both in different inertial reference frames, so time passes differently for the two of you. His frame was accelerating and near-lightspeed. Your frame was stationary the whole time. As a result, time passes different for the two of you and you can't mutually agree on what events between your two frames were simultaneous, or in what order they happened. Since clocks measure time, it's easiest to see the effects on clocks, but GR isn't something that happens to clocks, it's something that happens to time.

Muon decay? Surely ICANT can't think that a subatomic particle somehow contains a functioning clock.

Time is a quality or aspect of spacetime, and in this case spacetime is what is dilating. We know this is the case because objects in motion not only experience time dilation, they experience spacial contraction along the axis of travel - they get shorter - and mass increase as a function of their velocity. These are all the result of how objects in fast motion warp spacetime. It continues to be performed with muons, with the result that muons, which like all particles have constant half-life, experience a longer half-life when they move at relativistic velocities. We've observed that electrons have a greater mass when they are accelerated to relativistic velocities.Offhand I don't know how they proved length contraction, but that happens, too. Funny, I guess, but clearly inaccurate - clock B passes fifty years; clock A is the one that only ages 8.

Because they're set to run slower than Earthbound clocks (according to their own frame of reference) so that they stay synchronized with clocks on Earth (according to our frame of reference.) Well, ok, but GR and SR are probably second only to evolution in the weight of unexpected experimental and observational confirmation of the theory. I mean, we can look and see all over the place where things in the universe behave relativistically.

Objects are never relative to each other, their characteristics are. And it's already been explained to you what time is; it's a characteristic of spacetime.

It specifically has to be two twins, one on a spaceship? You wouldn't accept some other example of time dilation as a result of velocity?

No, this is incorrect, as we've very patiently explained. Time dilation isn't something that happens to clocks, it's something that happens to time. The "rate of duration" differs between different inertial reference frames. GPS clocks don't have to be corrected because their mechanisms slow down in high orbit - if you travel along with an uncorrected GPS clock to the same high orbit, you wouldn't perceive any degree of slowing down at all. You'd see Earthbound clocks speed up. But if you had stayed on Earth, you would have seen the clocks on Earth stay the same, but the GPS clock in high orbit would appear to be slower.That's not because of something that's happening to the clocks. It's because of something that's happening to the time where those clocks are. The stronger the gravity, the greater the force of acceleration, and therefore the slower the time. Vibration of atoms is a function of mass, not weight. Same as a pendulum.

Gravity is not a magnetic field, and moreover - the clock in space and the clock on Earth both "tick" at 9.192 ghz. If you're standing by the clock on Earth, it's ticking at 9.192 ghz. If you're standing by the one in space, it's ticking at 9.192 ghz.But the one in space has to be "corrected" - adjusted - to match the one on Earth (where we live, and therefore where we would like to tell time) because on Earth seconds are longer than they are in orbit.This is because gravitational fields don't change the way clocks run, they change the way time runs. It's actually the difference in times that your GPS uses to locate itself.

I think by "not alone" he's referring to the engineers referred to in the quote, the ones who doubted that GR corrections would need to be made - not his own beliefs.

Believe it or don't, but it happens. It has to happen, because the speed of light in a vacuum is the same for all observers regardless of their velocity.

Time is the reason things don't happen all at once. When time passes more slowly for one reference frame than for another, we say that time is being "stretched." The use of the word "stretch" is metaphorical; people intuitively understand time as being elastic so it makes sense to talk about it like it's literally made of elastic. But, again, that's just a metaphor. Almost everywhere. It's generally only as it passes through transparent materials that the speed of light is measurably different from its speed in a vacuum.

You can believe that, but it's wrong. The frequency of cesium oscillation - in its reference frame - is identical regardless of where in space it is.We only have to correct orbiting clocks because we want them to synchronize with non-orbiting clocks on Earth. We live on Earth, obviously, so this is where we want to tell time, so we want clocks in orbit, in a different reference frame, to synchronize with clocks in the Earth's reference frame.So, we slow them down by treating slightly more oscillations of cesium atoms in space as "one second", compared to the number of oscillations of cesium atoms on Earth defined as one second. No, that's exactly wrong. The speed of light is the same for all observers regardless of their speed. This is fundamentally true. For this to be true, however, time, length, and mass have to be relative to your reference frame. Hence "general relativity".

Time is the duration between events. Or, as I said - time is the reason things don't happen all at once. Yes - it's time. These figures refer to the mass within the universe and its composition, not the universe itself. The universe is made of spacetime. The mass within the universe is 5% visible matter and the rest is some combination of dark matter and dark energy. But the universe doesn't contain all that much mass so there's plenty of room for there to be no mass; i.e. a vacuum. The universe is not 100% energy and matter.

You have to understand - ICANT believes that any degree of agreement with us - even agreeing that cancer is bad or the sky is blue - is the first step on the road to atheism and damnation.

No, he just argues.I assure you, he had manufactured absolutely nothing about physics prior to this thread. As soon as you, or someone else on our side, used physics to argue with something ICANT said, ICANT knew that he had to argue against physics with whatever sources he could find.He's not doing any of this on his own; it's just that if we say it, he has to produce an argument that we're wrong. Otherwise he's going to Hell.