I thought the speed of light was the maximum speed anything was capable of so the missile wouldn't fire beyond the first spaceship.
Interesting question - Are you Sheldon?
The universe as we know it.
- Thread starter thelorax
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I thought the speed of light was the maximum speed anything was capable of so the missile wouldn't fire beyond the first spaceship.
Interesting question - Are you Sheldon?
So in essence, the photon that arrives at the mirror is the 2nd one in the chain of reacting electrons?
- 1st photon gets emitted by the light source (eg a light bulb); it arrives on your skin
- an electron of an atom of a molecule of your skin picks up the photon, gets excited, eats the 1st photon, copies it and radiates a 2nd one
- this 2nd photon is the one that arrives at the mirror.
How long does this chain get? If the photon coming from the mirror (the 3rd one in this chain) hits your skin again, it causes a 4th reaction, or does it not? So the 4th photon gets sent back to the mirror again, and so on, in perpetuity.
Could one then conclude that what we see (both in a mirror and through our eyes) is not how it REALLY exists (not saying "how it looks"!), given that it's a copy of a copy of a copy? This is assuming that no copy can be 100% the same as the original, given various diffusing and distorting variables that are being introduced in the process.
(O_o)
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wat? force does not depend on mass, and light's direction can be changed. you're trying to use Newton's laws...on a relativistic question. Stop it. I think I just answered my own question in the above post.
Strong gravity bends light *all the time*.
You also threw in their speeds like this even matters - since they're traveling at a constant speed, it does not. The only thing it would mean is relative to a stationary observer, a blue or red shift would occur depending on where the observer is.
You begin throwing in general relativity. And you are correct. But you cant introduce 5 strange new concepts at the same time. We will get there eventually. Historically, you go from classical mechanics to special relativity to general relativity, and we are at step two. Gravity bends light, but thats not due to "force". Its because gravity bends space-time.
I threw in their speeds because I wanted to show something cool, not because I thought it matters. That it doesnt matter has already been revealed. Do you want to challenge me on physics knowledge? We can talk theoretical physics if you want, but youd lack the very basics.
To answer your first question: Im not american, so our system is a bit different, but im definitely ahead of "bachelors" in your system. Im not a full time astrohphysicist if thats whats important to you, and thats because its a shitty job with very long hours and very shitty salary.
Just because we take a look at something relativistic doesnt mean that newtons laws dont apply anymore at all. You can make adjustments in the form of proportionality factors to them so that they still work.
Your first answer is incorrect.
On top of that, you are allowed to ignore gravitational effects.
Catholicism opens up more to science than youd think.
That chain goes on til your photon hits something black. But even black bodies radiate. Thats the heat radiation. Thats the mechanism that makes infrared cameras work. Body temperature corresponds to the wave-length of infrared light. If you heated the human body to the temperature of the sun, it will glow white, just like the sun.
You can obviously make that kind of interpretation. But photons dont lie. In the process of "reflection", energy is not lost. The adjustments your brain and eyes make are far bigger than the copying you describe.
In the case of a missile being fired, youd need to take a look at the amount of fuel the rocket contains. Its certain that it wouldnt get much faster than the spaceship it originated from and would take a very long time to reach its target. But that was not the point of the question, we were specifically exploring the behaviour of light.
Im not sheldon, but I understand whats written on the boards.
It "touches" the sun already. But since youve already learned that nothing can travel faster than light, this holds for sticks as well. So the correct "special relativity only" answer would be about 8 minutes. Just like the light takes 8 minutes to arrive at the earth. Thats a piece of info I assumed to be common knowledge.
But in reality, it gets weirder. Your stick is made of molecules. When you push it, each of those molecules has to be pushed by a molecule that is closer to you. This sends shockwaves through the stick and creates friction and your push would never arrive at the sun.
er, no. you might do well to look up what a "phonon" is.
Phonon - Wikipedia, the free encyclopedia
there's a reason I was working on a PhD and researching in solid state/condensed matter with work at the national high magnetic field lab.
Then I should apologize for assuming that you are not educated to an appropriate level. I dont want to make this some hostile discussion.
That I dont know much about solid state physics is a fact. Its not something that Im really interested in. The answer to that question is not something I have made up. It was being taught by a tutor and should, in restrospect, maybe not have been shared.
Would you like to share what you have worked on exactly?
That I dont know much about solid state physics is a fact. Its not something that Im really interested in. The answer to that question is not something I have made up. It was being taught by a tutor and should, in restrospect, maybe not have been shared.
Would you like to share what you have worked on exactly?
^Oh man wayn3, you really messed up. PJ here is actually Stephen Hawking. He told me so at ASW last year. :thumbsup:
BTW, I refuse to believe that since one stick is longer than another it no longer behaves like a terrestrial stick when you move it. I still say an inch of movement at one end of the stick is an instantaneous inch of movement 8 light minutes away at the other end. (It might take a shitload more force to move the stick 1 inch tho...)
For anything else to happen, the molecules between any two given side-by-side atoms inside that stick would have to behave differently, despite the fact that those atoms can't know if they're in a 1 foot stick or an 8 light-minute stick.
BTW, I refuse to believe that since one stick is longer than another it no longer behaves like a terrestrial stick when you move it. I still say an inch of movement at one end of the stick is an instantaneous inch of movement 8 light minutes away at the other end. (It might take a shitload more force to move the stick 1 inch tho...)
For anything else to happen, the molecules between any two given side-by-side atoms inside that stick would have to behave differently, despite the fact that those atoms can't know if they're in a 1 foot stick or an 8 light-minute stick.
Stephen Hawking didnt do a PhD on condensed matter
.You approach the problem the wrong way. Your terrestrial stick subject to relativity just as much as the long stick is. Its just such a small object that you dont observe the impact. If your stick went from east to west coast, the movement would surely not be "instantaneous". Definitely not faster than the time it takes for light to travel that same distance.
Ok, so let's zoom down to the molecular level. When you move one molecule 1 inch forward, the one in front of it moves the same amount of distance forward, being pushed by the molecule you moved.
Why would the front molecule in the long stick move LESS than 1 inch forward than a front molecule in the short stick does? It doesn't know which stick it's in... And gravity isn't forward.
Why would the front molecule in the long stick move LESS than 1 inch forward than a front molecule in the short stick does? It doesn't know which stick it's in... And gravity isn't forward.
I have a question. Please don't send mockery in my direction if this is a stupid question. I barely did high-school physics.
Is the speed of light really the fastest anything can travel at?
As far as physicists are concerned, yes. This is not set in stone or some absolute truth or something like that, but its relatively likely that it is. There have been recent results by a group that might or might not have measured neutrinos at a speed faster than light. They are at the moment trying to figure out whether it was caused by faulty measurements or some actual new physics, of which the latter is way less likely.
You probably imagine matter like this: Solid balls sitting tightly packed next to each other. If one of them moves the next one has to move as well because they cant occupy the same space.
Heres how it really is:
Lets take an atom. Atoms are made of protons and neutrons, which are made of even smaller particles. Thats the core of the atom. Its about 10^-15meter wide. Then there is the space around the core which is occupied by the electrons in some way. Thats the shell. The shell extends orders of magnitude beyond the core.
Maybe if you want to visualize that, imagine one of those big balls some people use instead of a chair because its good for the back or something. If that was the size of a real atom, the core would the sharp end of a needle sitting in the middle.
When two atoms bump into each other, they do that in a way similar to how two such balls would bump into each other. By approaching the other atom, they would invade their shell, feel a repulsive force and get pushed due to that force. That process is not instantaneous but takes very small amounts of time.
A very big part of an atom is just empty space, governed by strong fields that exert forces when you enter them.
Back to your question:
If you push a long stick an inch, every molecule travels 1 inch, just like in a short stick. What changes is the fact that it takes a while for the "push" to arrive at the molecules at the end.
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