microwaves ever get to my food to cook it? Wouldn’t the particle/waves appear to stop moving relative to me? Wouldn’t electrons attain infinite mass since they too are traveling at the speed of light? No doubt this is probably one of the dumber questions on the board.
All electromagnetic does travel at the speed of light of the medium in which it propogates. The upper limit is c, the speed of light in a vacuum. But I don’t see how this has anything to do with your microwave.
Why would you think that? I hesitate to get into a long explanation of special relativity if there is some basic question that can be easily answered.
** Well, yes, they would, if they were travelling at c, which they aren’t. Why do you think they are? Your microwave doesn’t use an electron gun. If you have an old-style monitor, it is using an electron gun to create the image on your screen. These electrons are moving quite fast, but not at c.
Hard to say as I don’t comprehend the assumptions underlying your questions.
Kid, a couple of points: The constant C (186,282.xxx MPS) is the speed of light (or other EM radiation) in a vacuum. The speed of light in other media is quite high but not quite C.
Only from the point of view of a hypothetical sentient photon would time stand still and motion cease – from your perspective that photon would move at the speed of light in air.
Particles with rest mass require an infinite amount of energy to accelerate to the speed of light (which hence becomes a never-achieved limit for them) and would have infinite mass if they ever did. But particles with a rest mass of zero, such as photons (and possibly gravitons and neutrinos), not only do not acquire mass of any sort (other than perhaps “kinetic mass” AKA momentum) from moving at light speed but cannot go any slower than the value of light speed for the medium through which it passes.
Ok, I’ll elaborate.
Let’s assume we’re in a vacuum.
My understanding was that as a mass approached the speed of light, time slowed relative to a “stationary” object and completely stopped at c. I’m thinking of the twin paradox here. If the one twin reaches the speed of light then time will stop for him relative to the observing twin. He’ll just freeze in space and not get any older (ok so that’s not exactly how it happens). So if electrons have mass and move at the speed of light, how can they ever appear to move relative to us? I’m sure there is an obvious answer but it’s escaping me.
BTW I know microwaves don’t use an electron gun, that was a seperate statement.
Electrons have mass, but they don’t move at the speed of light. It is PHOTONS that move at the speed of light.
Your microwave oven is producing photons of a frequency of around one gigahertz. From the point of view of a “sentient photon,” there is no time and everything happens at once. From your point of view, the photon moves at the speed of light.
Let’s see how much of a fool I can make of myself.
The concept of time slowing town has to be tempered with the fact that you have to have events to measure.
In the twin “paradox” (which isn’t really a paradox by the way), the only reason you know your twin, rocketing away at nearly the speed of light, has time passing slower for him relative to you is because you are observing him. Specifically, you’re observing something like a clock that he has with him and you can see that it’s not just that he’s moving slowly as a gag – the visible ticks of the his clock (let’s say there’s a light pulse from his ship every second), as they arrive in your eyes, are slower than the ticks of an identical clock that you hold.
However, you cannot deny in this thought experiment, that your twin is rocketing away in his spaceship at almost the speed of light. Regardless of the fact that the events aboard the ship seem to be passing slowly doesn’t change the fact that the spaceship itself is moving at nearly the speed of light. Your twin will, therefore, make it to Proxima Centauri in 4 years and change, just like he should, moving as fast as he is. You can measure his speed – just bounce some radar off him, or view any light he’s giving off that has a known frequency. The doppler difference denotes his speed.
In your microwave, electrons aren’t actually being ‘beamed’ at your food, but this is immaterial. Electromagnetic radiation is, as photons. But the photons still hit your food. Time ‘aboard’ the photon may be at a standstill relative to you, but there’s nothing on board the photon to ‘signal’ a passage of time to you. If someone could attach a clock to the photon travelling at the same rate, you could measure the zero rate of passage of time, but you can’t, so the question is slightly meaningless.
Nevertheless, as I just said, the photons still hit your food, just like your twin’s spaceship still rockets away at some speed.
In summary, you are assuming the propogation of the twin/photon at a rate near or at the speed of light in order to discuss the slowing of time. You can’t then say that the slowing of time slows down the propogation of the twin/photon. The spaceship still moves at nearly the speed of light. The photon still moves at the speed of light.
All of this is measured relative to the ‘stationary’ observer, you, of course. You can turn this around and view it from the position of the traveller, but it has little meaning when riding around on a photon. 
IANAP (not a physicist), but I dabble in this stuff via my work.
ummm, for some reason I feel compelled to point out that Photons ARE light, photons=light=photons, so there should be nothing confusing or strange about photons moving at the speed of light.
You could just as easily call it the speed of photons, although that might generate some arguments on particle vs. wave theory. Which is probably why they chose to go with the more generic term, speed of “light”.
The clocks on an object moving at .9c run slow, but this doesn’t affect the clocks of the stationary observer, and he will continue to see the object moving at .9c.
And BTW a photon can’t have a frame of reference because light must move at c relative to all frames of reference and light can’t move at c with respect to light.
And as an aside the vast majority of physicists do not use the term relativistic mass. Mass is mass and refers to the rest mass, or rest energy, or the energy of a system that can’t be transformed away. (m[sup]2[/sup] = E[sup]2[/sup] - p[sup]2[/sup] )
m = mass
E = energy
p = momentum
(c =1)
Excust me, I should have said:
"The clocks on an object moving at .9c run slow with respect to the clocks of a stationary observer."
Either observer can consider themselves to be at rest.
Provided they don’t accelerate, naturally.
Why sentient? Right now I’m reading Fashionable Nonsense by Alan Sokan & Jean Bricmont and, in response to Bruno Latour’s complaint that observers in a relativistic thought experiment are human and must be disciplined into merely looking at their watches, S&B note that “for Einstein, the ‘observers’ are a pedagogical fiction and can perfectly well be replaced by apparatus; there is absolutely no need to ‘discipline’ them.” pg 128.
So not sentient… it doesn’t matter whether the measuring device is sentient or not – it still has to be able to ‘emit’ a detectable event to the observer (or to store time-stamped detection of an event that the observer emits, reversing the roles) for there to be a meaningful measurement of elapsed time.
Which is great as long as you’re measuring a spacecraft travelling at nearly the speed of light, but naturally impossible if you’re trying to attach such an apparatus to a photon travelling at the speed of light. But if you could attach such a device to a photon without affecting it, it’d still be moving at the speed of light, even if its time is elapsing at a rate of zero seconds per your second.
Now I’m confused. I had taken it that…okay, suppose that a comet 15 billion light years away (far enough that we’ll never find out about it) hooks around a star and flies away at an appreciable percentage of the speed of light. The comet and the star are now in two different frames of reference and, since one is going so fast, they are experiencing two different times. No one has to be there for the physics to operate. Kind of like how a tree falling in the woods, when no one is around to hear, still moves air as it falls thus it still makes a sound. That’s how I understand it. But I don’t know much about physics.
JS…
I think what they are saying is “yes, crazy stuff happens from the point of view of the photon, but it doesn’t matter because we aren’t on the proton from our point of view everything is great, and since we can never get to stand on a photon its never gonna bug us too very much”
That’s all perfectly true, africanus, but these thought-experiments are meant to be predictive. There’s not much point in predicting the behavior of a system when you preface it with “You’ll never see this, but…” So we imagine an observer with a mechanism for creating a distinction between moments in time (a ‘clock’) and sending signals to an observer in another time frame – it makes things easier to think about. The actual experience of a comet can be timed by the rate of outgassing, but we like things that act sentiently. Sue us.
You can, as a thought experiment, know that the comet must have a slower rate of time than the star, even if you never saw the comet and somehow magically ‘knew’ it was on its way. You can know this based on relativity. But if you want to show how relativity works, you can’t use relativity as an argument. So unless you’re measuring the other frame of reference in some way that allows you to determine the passage of time, the question as to what rate time passes is somewhat meaningless.
The tree-in-a-forest analogy is apt… you can imagine the tree could be falling, but you can’t prove it until you measure it.
You can’t prove time is passing slower on your receding comet relative to the star unless you measure at the star something periodic coming from the comet and you know how fast that periodic something really should be if you were travelling with the comet.
With regards to a photon of microwave radiation, then, the question of the passage of time ‘on’ the photon is somewhat meaningless. Based on relativity we suspect that time is ‘at a standstill’, but we have absolutely no way of measuring it. We can measure (and do measure) slower things, so we know relativity is a pretty good description of the way things work in the universe, and we can extrapolate forward mathematically. Again, though, no way to prove what the passage of time is like on the photon, relative to you.
And none of this affects the fact that the comet is travelling at that appreciable fraction of the speed of light. With regards to the OP, the photons still hit the food, regardless of whether or not time is passing faster or slower when travelling with the photon. The passage of time on the photon is not the time with which you are measuring its travelling from the microwave emitter to the food. You’re measuring using your own time frame.
From your point of view, the food gets ‘bombarded’. Your twin, riding piggyback along with one of the photons of microwave energy, may be experiencing no passage of time relative to you, but he’ll impact the beef stroganoff all the same.
I thought that as you approach the speed of light your mass increases as does the warpage of space around you. Since space collapses around the extremely high mass, it moves through a relatively normal amount of space relative to itself but very little relative to us which is why it appears to slow down. Before I go any further, is this right?
Why would I want to do that? I think you may have misinterpreted my tone.
** Nametag, William_Ashbless, & owlofcreamcheese**, thanks. Now I’m not as confused.