EPTread more, thanks for the links. even though i dont try to think about the math, i like the concepts they use the math to support and just take their word for it.
Special Relativity - Page 2
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MiniRoman
Canada3953 Posts
read more, thanks for the links. even though i dont try to think about the math, i like the concepts they use the math to support and just take their word for it. | ||
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Nuttyguy
United Kingdom1526 Posts
so E8 x10^8 its like on the calculator (EXE) or whatever brand you have | ||
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quirinus
Croatia2489 Posts
On April 25 2011 01:59 XsebT wrote: Quite obviously just false as I see it. What confuses me about this subject / way of testing it as a whole though is that this movement is only relative to our planet - not space. Imagine the Earth is right this second traveling (around the sun) through space to the direction you would call "west". Then imagine you started driving east. Wouldn't you then essentially slow down your own speed i space? I have no idea how this works, but that would seem logical to me. At least if our speed can at all be considered independent from that of the Earth's. Please correct me. The only thing that matters is the frames you choose and their relative speed. If you choose the Earth and the car and measure the car relatively towards the movement of the Earth (ie. Earth is stationary in this reference frame), the speed of the Earth is 0, because you used a reference frame that is moving along with the Earth (in which Earth has 0 speed), so the speed of Earth (towards the third reference frame - "universe") doesn't have any say in the measurement - only the relative speed of the car and the Earth play a role. ^^ To conclude, only the relative speed between two reference frames is important. Also, note how this is very convenient. Xou have no way to know the real speed of Earth, as it "orbits" around the center of our galaxy, and the galaxy orbits around the cluster of galaxies etc. and it's hard to find the "center" of the space... But as only the RELATIVE speed of the two reference frames is important, we don't need to know it's speed. | ||
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MiniRoman
Canada3953 Posts
On April 25 2011 02:29 Nuttyguy wrote: E is x10^y so E8 x10^8 its like on the calculator (EXE) or whatever brand you have so "damn fast" was right? | ||
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green.at
Austria1459 Posts
On April 25 2011 01:42 Bippzy wrote: What happens if you're going at the speed of light? In theory. Also, happy birthday! all i know is that it would burn like hell  | ||
micronesia
United States24673 Posts
On April 25 2011 01:25 OrchidThief wrote: Wow. What on earth motivated you to post all this? Interest. On April 25 2011 01:37 DarkPlasmaBall wrote: I assume he just paused one of the timers for two seconds off-camera. Yea or something similar. On April 25 2011 01:42 Bippzy wrote: What happens if you're going at the speed of light? In theory. Also, happy birthday! You can't travel at the speed of light according to Einstein. Just like how t' = t * Gamma = t / sqrt (1 - (.5c)^2/c^2) you can say E = mc^2 / sqrt(1 - (.5c)^2/c^2) thus when your speed is c your energy (E) is infinite. You would need an infinite amount of energy to accelerate an object with a nonzero mass to the speed of light. On April 25 2011 01:42 DarkPlasmaBall wrote: Is this simply false because he's not going nearly as fast (or for as long) as he needs to be going for any actual time dilation to occur? Yes. On April 25 2011 01:45 Antifate wrote: This was fun to read, but I have a question. So when "time slows down" for the running guy in the first segment, both he and the stationary observer see light going at its 3E8 speed. But how fast does the runner appear to the stationary observer? Edit: Lol, it's 2.9E8 m/s isn't it? Kind of dumb.  Good question. You will need to read about relative velocity like I mentioned... time dilation causes the answer to be different than you expected. On April 25 2011 01:59 XsebT wrote: Quite obviously just false as I see it. What confuses me about this subject / way of testing it as a whole though is that this movement is only relative to our planet - not space. Imagine the Earth is right this second traveling (around the sun) through space to the direction you would call "west". Then imagine you started driving east. Wouldn't you then essentially slow down your own speed i space? I have no idea how this works, but that would seem logical to me. At least if our speed can at all be considered independent from that of the Earth's. Please correct me. There is no universal reference frame that we know of. Everything about relativity is relative (surprise surprise). It's common to use the sun or the Earth as a 'fixed' reference point. On April 25 2011 02:05 HwangjaeTerran wrote: That's one ugly car. Also I love how it's a Special theory. It would be far less interesting if it was Einstein's Just Another Relativity Theory. That guy knew how to sell his theories. Yeah but I hope you see there is also a good 'scientific' reason for why he chose that name :p On April 25 2011 02:15 radscorpion9 wrote: Thanks for writing this up; I was always interested in physics and special relativity/general relativity, its nice that you found a way to clearly and concisely explain this topic. The next thing I wish I could understand is how gravity is explained or related to the bending of space-time  . I wish I took physics instead of engineeringWe could discuss general relativity a bit more qualitatively I guess, but I cannot help you with the math behind it :p On April 25 2011 02:16 ShowNun wrote: Isn't this video fake because wouldn't the stopwatch he took with him in the car be ahead of the stopwatch left at home? The stopwatch in the house would 'age' faster and would read a larger time. Time slowed for the stopwatch in the car. | ||
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Mr. Wiggles
Canada5894 Posts
On April 25 2011 02:36 quirinus wrote: The only thing that matters is the frames you choose and their relative speed. If you choose the Earth and the car and measure the car relatively towards the movement of the Earth (ie. Earth is stationary in this reference frame), the speed of the Earth is 0, because you used a reference frame that is moving along with the Earth (in which Earth has 0 speed), so the speed of Earth (towards the third reference frame - "universe") doesn't have any say in the measurement - only the relative speed of the car and the Earth play a role. ^^ To conclude, only the relative speed between two reference frames is important. Also, note how this is very convenient. Xou have no way to know the real speed of Earth, as it "orbits" around the center of our galaxy, and the galaxy orbits around the cluster of galaxies etc. and it's hard to find the "center" of the space... But as only the RELATIVE speed of the two reference frames is important, we don't need to know it's speed. I was basically going to say this, but also keep in mind that you require an inertial frame of reference for special relativity, meaning your frame of reference can't be accelerating. | ||
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Aquafresh
United States824 Posts
On April 25 2011 01:59 XsebT wrote: Quite obviously just false as I see it. What confuses me about this subject / way of testing it as a whole though is that this movement is only relative to our planet - not space. Imagine the Earth is right this second traveling (around the sun) through space to the direction you would call "west". Then imagine you started driving east. Wouldn't you then essentially slow down your own speed i space? I have no idea how this works, but that would seem logical to me. At least if our speed can at all be considered independent from that of the Earth's. Please correct me. Keep in mind that not only are we (the earth) in constant motion around the sun, but the sun is orbiting the center of the milky way galaxy, which is itself hurtling through the local group at a great speed relative to its gravitational center, which is also moving with some speed relative to some other celestial object. The bigger things get the less sense it makes to measure things like "speed" on that scale. It becomes a meaningless question to ask "how fast is our galaxy/star/planetary system traveling through space?" since there are an infinite number of equally valid answers given the vague context. | ||
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divinesage
Singapore649 Posts
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micronesia
United States24673 Posts
On April 25 2011 02:25 MiniRoman wrote: only read beginning but wouldn't that little proton of light travel at the speed of light? Too fast for any human "observing" without the tools of science. Therefore wouldn't the answer to the proposed "what would the observer see" "nothing" cause you can't detect a single glimpse of light or prolly anything moving that fast. Iunno how fast moving numbers with the letter E added on to them are, but I assume its damn fast. read more, thanks for the links. even though i dont try to think about the math, i like the concepts they use the math to support and just take their word for it. First of all it's technically a 'photon' of light. A proton is a particle and thus has mass and cannot travel at the speed of light :p As someone else pointed out E means "x10^" so c = 3E8 m/s = 300000000 = very fast On April 25 2011 02:50 divinesage wrote: You forgot to add that it would then be impossible to achieve the speed of light. Happy Birthday! See my recent post :p | ||
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synapse
China13814 Posts
Happy Bday micronesia! Thanks for writing this stuff up | ||
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Nuttyguy
United Kingdom1526 Posts
Yes light can travel 7.4 times around the earth in 1 second to put things into context. How would they measure the speed of light? And mass increase with speeds near speed of light, so a light photon's mass would increase. Does the photon slow down with the maximum speed being speed of light? EDIT unless you treat it as a wave because of its wave-particle duality? | ||
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Z3kk
4099 Posts
What I'm wondering is why you got zero responses after your first two posts LOL April 10, April 10 ... ... .. April 25 :o | ||
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Duka08
3391 Posts
On April 25 2011 01:42 Bippzy wrote: What happens if you're going at the speed of light? In theory. Also, happy birthday! While micro above just showed that it is indeed impossible to do so, imagining this has always been one of my more interesting thought experiments / curiosities. If time dilation and length contraction actually worked as described AT the speed of light (which we can not know), lots of interesting things would happen. The way I always enjoy imagining it is, picture you're just stand still in space, on a space station or something. There's a platform coming up behind you that will whiz by you at the speed of light exactly, which you can step on. What would happen if you did? Length contraction and the aberration of light says all the light in the Universe would be focused to a single infinitely small point directly ahead of you. You would see nothing all around you. In addition, time would dilate "infinitely", so when you stepped on for a fraction of a second and decided to step off again, you could be anywhere, or the universe might not even exist (assuming you didn't run into anything!). Other interesting things like the Doppler effect as well... very fun stuff! On April 25 2011 02:57 Nuttyguy wrote: And mass increase with speeds near speed of light, so a light photon's mass would increase. Does the photon slow down with the maximum speed being speed of light? EDIT unless you treat it as a wave because of its wave-particle duality? Photons, the way we treat them as particles, have NO mass. Ever. They carry momentum and energy, but they have no mass. And they ALWAYS travel at the speed of light. | ||
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ShowNun
United States10 Posts
On April 25 2011 02:54 micronesia wrote: As someone else pointed out E means "x10^" so c = 3E8 m/s = 300000000 = very fast And for people who don't have a concept of how fast a meter per second is, you can get a rough conversion to miles per hour by just multiplying by 2. So 300,000,000 m/s is about 6 hundred million miles per hour! | ||
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Luddite
United States2315 Posts
On April 10 2011 00:18 micronesia wrote: A car is driving to the right with a speed v, as shown in the picture. Mounted to it is a laser pointer (orange) shooting light up towards the ceiling. The ceiling is a mirror and reflects light back down towards the ground. A detector on the car determines how much time it took the light to return to the car after being emitted by the laser. There are two reference frames to discuss: I already know all about special relativity, and I know that this setup gives the correct math. But this example always really bugged me. The problem is that it depends on a specific kind of clock. I don't think you can generalize from "this specific kind of clock that relies on laser beams slows down" to "time slows down". There are better ways to derive the lorentz equation for time dilation. | ||
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Hoban
United States1600 Posts
On April 25 2011 02:57 Nuttyguy wrote: Yes light can travel 7.4 times around the earth in 1 second to put things into context. How would they measure the speed of light? And mass increase with speeds near speed of light, so a light photon's mass would increase. Does the photon slow down with the maximum speed being speed of light? EDIT unless you treat it as a wave because of its wave-particle duality? You can mathematically calculate the speed of light in a vacuum by the permittivity and permeability of electric and magnetic fields (they are universal constants). One way to find these constants is to take special relativity cases which involve charges and/or currents in inertial reference frames. I must say Micronesia, awesome post! I am glad to see some other people on TL who are scientifically minded. I think it would be cool to then express special relativity to the TL community with space-time diagrams. People seem to have a grasp of time dilation and length contraction, so maybe we can move into geometry Happy Birthday! | ||
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phyren
United States1067 Posts
It is harder to increase speed as you are going faster. That is, the amount of energy that is needed to speed up from 1 m/s to 2 m/s is not as much as moving from 9 m/s to 10 m/s. This is true in both classical mechanics and relativistic mechanics. Theoretically, it would take an infinite amount of energy to accelerate any massive object to the speed of light, thus the only way an object can travel at the speed of light is if it has no mass (i.e. photons of light and other force carriers such as gravitons gauge bosons). | ||
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Dagobert
Netherlands1858 Posts
On April 25 2011 03:00 Duka08 wrote: Photons, the way we treat them as particles, have NO mass. Ever. They carry momentum and energy, but they have no mass. And they ALWAYS travel at the speed of light. Nope, they can be slowed down (Akopian et al., 2011). | ||
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hifriend
China7935 Posts
gj explaining this to a retard such as myself. Gonna have to fire up khanacademy after tsl3. | ||
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