If you started whirling a stick around in space at one revolution per second, how long would the stick have to be for the end to be traveling at the speed of light and if the stick was longer, would the tip of the stick travel backwards in time?
131324
Not only would you need infinite energy, but the stick would have to have infinite tensile strength. As the speed of the tip of the stick approached lightspeed, the mass would approach infinity. So the tip of the stick would begin to exert tensile stress along the length of the stick in direct proportion to the rising mass of the tip. Thus, without infinite tensile strength, the stick would break before the tip reached lightspeed.
284815
Depends on your perspective.  As you travel closer and closer to the speed of light, time for you will seem to be normal, but you will see it speed up for others who are stationary.\n\nIf you are the one who is stationary, time will seem normal to you, but it will slow down for the one traveling.\n\nAn example - your twin has just been chosen to go on an interstellar trip.  Thankfully you're telepathic and can communicate over any distance.  As she speeds up, you will notice that there are longer and longer times between her transmissions to you, even though she says she'd contacting you at the same time every day.  And when she returns to earth 50 years later, you find she's only aged 10 years! (Robert Heinlein wrote a great novel about just this scenario - "Time for the Stars").\n\nScientists have proven this amazing fact in many experiments. They've put an atomic clock on a fast jet and flown it around the world.  When they returned, the clocks had different times than those on the ground.  But not by much - the clocks were between 50 and 270 nanoseconds different than their stationary counterparts - that's 50 billionths of a second.  Not much - but 500 mph is pretty slow compared to the speed of light.\n\nAnother way this is used in everyday life is the GPS satellites.  This navigation system has to take relativistic effects into account in it's transmission signals in order to get the high accuracy it's capable of. Every GPS satellite has an atomic clock aboard.  Because of the speed of the satellites, a ground observer will see them ticking slower than real time, so the signals have to be adjusted.\n\nTo answer your question - if you traveled around the world at 700 mph for a week, you'd be a few thousandths of a second younger than your friends who stayed behind.
490961
A wheel mounted on a wall is rotating. Every second, its velocity advances 4 radians/second, which is equivalent to 229.183 degrees/second. That is, if it is moving at 0 degrees/second at time 0, it will be moving at 229.183 degrees/second after 1 second, and it will be moving at 458.366 degrees/second after 2 seconds. This is actually the answer to part (a).\n\n(a) The angular speed at t=2 seconds is 458.366 degrees/second, or 8 radians/second.\n\nWe assume that the wheel is rotating counter-clockwise. That is,  if you look at it, a point at the top of the wheel will move to your left.\n\nAt t=0, we focus our eyes on a point on the rim of the wheel. That point is located 57.3 degrees above the horizontal. That is, if the wheel was a clock face, the point would be located around 1 o'clock. 1 o'clock is located at 60 degrees above the horizontal, so the point is actually located at where the hour hand would point at 1:05, which is just passed 1 o'clock. (keep in mind that 3 o'clock is located at 0 degrees and 12 o'clock is located at 90 degrees)\n\nNow, at t=2 seconds, we already found that the wheel is rotating at 8 radians per second. Since the radius of the wheel is 2 meters, if the wheel moves 2*pi radians, the wheel moves 2*pi*r meters. Thus, there are r=2 meters per every radian. Thus,\nthe point at the edge of the wheel is traveling around the wheel at (8 radians per second)*(2 meters per radian) = 16 meters per second. Similarly, since the wheel is accelerating at 4.0 radians/second/second, the point at the edge of the wheel is accelerating along the circle that is the edge of the wheel at at (4.0 rad/s/s)*(2 meters/rad) = 8.0 meters/s/s. \n\nHowever, there is also an acceleration normal to the edge of the circle pointing toward the center of the circle. That acceleration is thus a "centripetal" acceleration, and is given by v*v/r, where "v" is the tangential speed of the point. We know the tangential speed is 16 meters/second, so the centripetal acceleration is 128 m/s/s. \n\nThese two accelerations (tangential and normal/centripetal) are perpendicular to each other, so the TOTAL acceleration is the length of the hypotenuse of the right-triangle formed with each of them on a leg. That is, the total acceleration is the square root of ( (128 m/s/s)^2 + (8 m/s/s)^2 ), which is 128.25 m/s/s.\n\nThus, the answer to (b) is:\n\n(b) The tangential speed is 16 meters/second. The tangential acceleration is 8 meters/s/s. The centripetal acceleration is 128 m/s/s. The TOTAL acceleration is 128.25 m/s/s.\n\nFinally, you want to know the angle where P is after 2 seconds. Since everything started at rest, you know that (you can derive these with a little calculus; keep in mind that acceleration is change in velocity over time and velocity is change in position over time):\n\nacceleration = 4 rad/s\n\nvelocity = acceleration*t = (4 rad/s)*t = 8 rad/s\n\nDISPLACEMENT = 0.5*acceleration*t^2 = 0.5*(4 rad/s)*t^2 = 8 radians\n\nSo the angle of point P has moved 8 radians, which is equal to 458.366 degrees. Since the point P has started at 57.3 degrees, then you just add 57.3 degrees to this number and you get 515.666 degrees. Now, there are only 360 degrees in a circle, so this means that the point has completed one revolution and has gone 155.666 degrees into the next circle. Thus, your answer to (c) is:\n\n(c) The angular position of the point P is 155.666 degrees.\n\nI hope that helps.
199357
So far time dilation is possible in the forward direction. That is if YOU travel away from earth in a very fast spaceship near the speed of light then turn around and come back. The people on earth would age more then you have. YOUR clock would be different then those people on earth. It would be faster.\n\nGoing backward in time is still up there.\n\nThere are many experiments that prove this to be true. Atomic clocks capable of high accuracy are sync up. One is put on a plane and flown around the earth at high speeds for a long time. When the two clocks were compared later, they showed a difference, a very small difference but a difference none the less.\n\nTake a look at this website. There are plenty of other site out there.\n\nhttp://imagine.gsfc.nasa.gov/docs/ask_astro/answers/050225a.html\n\nInterestingly, if you did travel at the speed of light, you would be anywhere and everywhere all at once... WOW! That blows my mind.    :-)
92291
A particle  in order to move it must start from a reference point. The velocity of the particle depends on the intensity of the gravitational field . Since the strenght of the gravity field is inversely proportional to a distance. Than the time that a process take place must be different at different parts of the Universe.\n\nSo far sCience has failed to prove that at the edge of the universe there exist such a field  so that the velocity of light would be much different than the reference frame that we measured from on earth.\n\n What seals the containment of the universe into a boundary was only understood by Einstein. No One else did. What are the limits of the velocity of light? We only were able to measure it on earth.But not at the outskitt of the universe.\nThe best answer is I dont know.\nSunthinks if your Soul and Spirit were to travel outside the Universe to Heaven,you certainly would have to travel faster than the speed of light!
109523
You can't reach the speed of light in any conventional way, but you can get as close as you want, provided you can keep applying acceleration.  \n\nThe best way to do a thought experiment of time dilation for special relativity (special relativity being the case in which you consider high velocities, general relativity just applies this same model to all spacetime trajectories with the observation that gravity is indistinguishable form a physical acceleration) is to consider the case of a "light clock".  \n\nFor a light clock, you have a laser pulse generator, a mirror at some distance, and a pulse counter next to the laser.  Everytime a pulse is recieved at the counter, another pulse is sent from the laser, and so you have a clock that "ticks" at a rate determined by twice the distance from the laser to the mirror.  So, what happens when you move this clock?  If the clock is arranged such that the pulse bounces back and forth perpendicular to the direction of travel, it's easier to get the basic idea.  \n\nThe speed of light is always constant, but as the clock moves at higher and higher speeds, from the perspective of a stationary observer the total distance traveled by the light increases, since now it's going diagonal.   But, to a person traveling along with the clock, it doesn't appear to travel any greater distance.  \n\nIt's something like a person standing in a train car or bus tossing a ball up and down.  While the ball is up in the air, it travels horizontally by the distance the bus has moved while it's been up in the air, so the total distance traveled by the ball is much longer if the bus is moving rapidly instead of stationary.  For normal speeds, the Gallilean transforms are sufficiently accurate, so a stationary observer and the person tossing the ball can agree how fast it's moving in each axis, and how far it moves, just by adding the horizontal velocity of the bus to the vertical velocity the ball is tossed with, and come up with the same wider parabola for higher speeds and narrow parabola for low speeds, or stationary cases.  \n\nBut, light has an interesting property...  it must remain at the same velocity for all observers no matter what their speed relative to the light.  So, in the case of a ball, we can simply say that it's moving faster than it looks to the person on the bus with it, because there's the added background horizontal velocity.  If you add the vertical and horizontal velocity vectors, the sum is longer than just the vertical velocity.  \n\nBut, in truth, how can you know if you're moving at a constant velocity?  There are no pseudoforces of acceleration if you're moving at a constant velocity, but if light behaved oddly by traveling faster in one direction that the other, you would be able to tell if there was a fixed frame of reference outside of your motion, and this would allow you to determine a fixed location relative to the universe as a whole, and even determine where the center of the universe is.  But it doesn't have a center, or all points are equally the center, depending on how you want to look at it, so there can't be any way to tell if you're moving at a constant velocity, and so light must travel at the same speed in any direction when viewed by any set of observers, no matter what their relative velocities are.    Not surprisingly, we find this also comes out from Maxwell's equations describing the propagation of light, the velocity winds up being proportional to one over the square root of the product of the electrostatic permittivity and the magnetic permeability of empty space, a number which is absolute and gives no preference for directions or relative motions.  This isn't surprising since, like I said, it's a necessary condition for a centerless universe.    \n\nSo, the speed of light must remain absolute, but something has to give.  Since the light clock is ticking slower becaus
21104
As you travel faster and faster, time for you slows down, and length contracts. From your point of view, when you measure the speed of light, it will always be the same. An observer standing still with respect to you and the beam of light could measure your speed at 185000 mps and the speed of light as 186000 mps, and say the difference in speed is 1000 mps. But that is relative to them. The speed of light will always be the same for whoever measures it, no matter how fast they are moving.\n\nSee the website below for more about relativity.
404852
Good question, shows you are thinking.\n\nPresent technology contends that only light, pure energy, can go as fast as the speed of light.\n\nTaking that theory to heart, if a space ship actually achieved the speed of light it would turn into pure energy (light) and cease to exist as a solid object. The test pilot would theoretically commit suicide in an attempt to learn if it was possible.
450167
The question deals with the expansion of the Universe, with the simplifying assumption that the object asserted to have an expansion speed away from us (by measuring its red-shift) has ALWAYS been traveling at 3,000 km/sec, and that its (known) distance is 50 Mpc.\n\nHowever, your requested operation is inverted!  That is obvious since any number of Mpc's (a length) divided by a speed (km/sec) will give one a time, but yours, quite the opposite, will give you 1 over a time.  Personally, I prefer my wristwatch to measure time t rather than t^(-1), but hey, if you could develop that, there might still be someone out there who'd want to buy it!\n\nLive long and prosper.
336206
Neither you, nor the train, could ever travel at the speed of light since both of you have some non-zero rest mass.\nIn order to accelerate something with a non-Zero rest mass, an infinite amount of energy would be required....and in the whole universe, there is not an infinite amount of energy.\n\nBut lets say you were traveling just under the speed of light...at 99.99999999999999% of c and you began to run toward the front of the train, \nyou would still NOT be traveling at or above the speed of light (as seen from an outside, "stationary" observer) since at relativistic speeds such as this, velocities do not add in the normal Galilean way, you would still be traveling slower than the speed of light.
285974
No there is no 'summation' of speeds involved with light.  Light is Electro-Magnetic Energy, although light travels as particles as well as waves.  In this Universe the speed of light is a constant, roughly 186,000 miles-per-second, or 300,000 km/sec or 300 Mega-Metres / sec.  Unless some POWERFUL external force acts upon light, it cannot change speed.  This entails the gravity of black-holes and such. (Not even light can escape from them.)\n\nA vehicle might weigh somewhere in the neighbor-hood of 3,300 lbs. (Approximately 1,500 Kg, for those of you who have not learned to count properly, just yet ...)\nCheck out da' math ...\n\n60mph = 100 kmph = 27.77r mps. \n(1,500 Kg x 27.77r mps) / 9.81 mps = ~ 4,246 N\n\nI doubt, very seriously, that a little over 4,000 Newtons is enough force to even put a dent in the factor of light-speed.  For more info, look-up Einstein's Theory of Realtivity' (Although I believe 90% of it to be short-sighted ancient crap ...)  This subject is covered in it ...\n(umm covered in Einstein's Theory, not copvered in crap .. which err .. is the same thing at times ...
478669
Going faster than light speed violates the laws of special relativity.  You simply cannot start at rest or any velocity less than light, reach light speed, then get faster.  However, it does not violate special relativity if your starting velocity is faster than light.  This is how tachyons are hypothesized.  When a tachyon forms, it immediately starts which a velocity faster than light.  Therefore it can never slow down to the speed of light or less.  If tachyons exist, they'll give off a certain type of radiation so they won't be invisible. \n\nSo in other words, it will never be possible for us to make some spaceship or anything that can go faster than light, which means no "warp drives" or anything like that.
474799
You wanted a serious answer so here goes.\n\nWhat you ask is impossible to put into practise. It is impossible under Einsteins theory for anyone to travel at the speed of light.\n\nSimply put I will try to explain why,, as you approach the speed of light matter expands or rather the mass does. According to the research , the speed of light would produce infinite mass so it is impossible to travel at that speed.\n\nThat's were the theory of worm holes came about, by creating a rip through space you can jump if you like from one point to another, crossing several light years of travel in an instant. But as you have made use of a warp in space itself you don't actually go the speed of light.\n\nSo basically, you cannot answer your question,, I can see were you get this idea from though as it is true that the faster an objects velocity is, the slower time passes for that object.\n\nThis was proven some 50 years ago by use of atomic clocks on a plane, one flew round the world while the other remained in London. When they were brought together it was noted that time passed slower for the moving clock.\n\nHope this helps.
123758
I'm sure you are spekaing strictly hypothetically, but don't forget the closer you get to the speed of light (c), the slower time moves around you.  So if you were to go like 90% of c for 1 year, more than 1 year would pass for everyone else.
143939
Wow, great question(s)!  You're brooding over something called the 'twin's paradox', read more about it in the link below.  Basically, what you're fretting over are a couple of the (wierd) implications of special (and general) relativity.  You (and what some others have said) are right, all velocity is relative, which comes from the simple fact that there is no special place that we can call 'still' which we could measure our velocity against.  The single exception to this lies in the speed of light, which is constant for everyone everywhere, no matter what their speed is relative to anything else.  (Note: light isn't special, the only reason it's able to travel at the upper speed limit is because it's particles, photons, have no mass.  Nothing with mass can ever travel AT the speed of light, only near if it is pumped up with huge amounts of energy.)  Think about the wierd implications of this; even if you were able to travel at 99.999999% the speed of light, and your friend would also be able to travel the same speed in the opposite direction, if you shined a light back toward your friend and could measure the photon's speed as they travelled between you the photons would STILL be travelling at the speed of light.  Ok, what does that mean?  The speed of light is just a speed, like any other, but is a constant that can not be exceeded.  Well, like any other speed, c (the usual symbol for the speed of light) is definded as the ratio of the distance travelled (call it 'x') by the time it took to travel it (call it 't'), or c=x/t.  But if 'c' can't change (because it's a constant) what is changing?  There's only two other things in the equation, x (the distance, a measure of space) and t.  Time and space enter into Einstien's equations here, the only way to keep c constant is for x and t to somehow collaborate to change together to make it so.  This is why time (and space) are so 'relavent' to velocity.  And as a matter of fact, time is 'relavent' to gravity as well, as Einstein pointed out so much better than I can.  For Einstein, the breakthrough came when he realized that there is no measurable way to distinguish between gravity and acceleration (a.k.a. the rate of change of velocity with respect to TIME), or more importantly, between the lack of gravity (say a person floating in space) and a particle (or person) in a falling box, they're indistinguishable.  From these two simple ideas (the constancy of c, and the equivalence of gravity and acceleration) Einstein formulated the theory of general relativity, one of the crowning achievements of human thought.  You ask good questions, keep wondering!
485664
Since the propeller has three blades it will look the same every 1/3 of a revolution.\n\nThe propeller does 13.4 rev/s, or 0.0746 s/rev (Just take 1/13.4).\n\nMultiply how many seconds it takes to do one revolution by 1/3, because this is how often the propeller will look like it did in the beginning:\n\n0.0746*(1/3) = 0.0249s\n\nSo, the shortest time between flashes to make the propeller appear stationary is 0.0249s.\n\nThe next shortest time will be twice this (0.0498s) because in 2/3 of a revolution the propeller will again look as it did in the beginning.
504475
If you apply a force to move an object, you produces work, and this work is equal to the kinecti energy change.\n\nThe speed of light is not force!!!!