Posted on 06/22/2017 9:45:54 PM PDT by Vendome
The universe could already be over on the other side, someone could have initiated a vacuum decay.
No it won’t! The transmission itself isn’t travelling away from the viewer at the speed of light. Only the ship is. The transmission is travelling in the opposite direction relative to every position of where the ship IS when broadcasting. The waves don’t travel with the ship. They are INDEPENDENT of it. Thus not relative to the ship, but to the viewer.
The sci-fi juvenile novel “Time for the Stars” by Robert A. Heinlein postulated that twins could use psychic powers to communicate simultaneously if one traveled in a ship at light speed while the other stayed on Earth. Interesting idea.
No. The relative rates of time passage are strictly dependent on relative speed and do not depend on distance whatsoever. A message sent from a craft traveling at 1/2 light speed will be slowed by the same amount ("the time within the video") regardless of whether the source is a foot away or a light year. This holds true no matter what the difference in relative speed is; it simply isn't noticeable when the velocities are very close to the same value. If we could actually distinguish it, the time rate of the guy walking toward the front of a moving bus is slower than that of the guy sitting in a seat, and both are slower, but not equally so, than that of a guy standing on the street as the bus goes by.
The latter. Light always travels at the speed of light (in what ever medium), regardless of the speed of the sender or observer. It would be red- or blue-shifted due to the Doppler effect. But even if you had two parties traveling at 99% of the speed of light in opposite directions, not only would light transmitted between the two still appear to travel at the speed of light, neither one would see the other as traveling faster than light. They might see each other traveling at 99.99% (I didn't do the actual calculation, just giving an example) of the speed of light, but not in excess of it.
Actually, while they were traveling, beyond a certain relative velocity they could not communicate due to time dilation slowing down the one on the ship too much, but when they slowed down to check out a planet they could sometimes reestablish communication. The benefit of the twin telepathy was that it was instantaneous rather than limited to light speed, so they could communicate without long delays.
There was a sci-fi movie for kids that addressed this issue of delayed or late transmissions receptions. I think it was called “The Explorers”. Pretty sure it had River Phoenix in it.
All about their communicating with an alien spaceship whose teenage inhabitants talked like people in TV ads from the 1950’s (which were the transmissions they were receiving and learning from out in deep space).
If we go fast enough, perhaps we will run into the first season transmissions of “Twilight Zone”.
Don’t forget to bring some popcorn, because “In Space, There Is No Popcorn”.
Its all relative. On earth the live video would be considered delayed, not much from the space station but from mays it would be about 14 minutes.
GPS satellites move at way less than the speed of light, but GPS calculations still need to account for Special and General Relativity. Special Relativity slows the satellites' clocks by about 7 microseconds a day, but General Relativity speeds them up by about 45 microseconds/day. The net is, they gain about 38 microseconds per day. From this link:
To achieve this [high] level of precision, the clock ticks from the GPS satellites must be known to an accuracy of 20-30 nanoseconds. However, because the satellites are constantly moving relative to observers on the Earth, effects predicted by the Special and General theories of Relativity must be taken into account to achieve the desired 20-30 nanosecond accuracy.
Because an observer on the ground sees the satellites in motion relative to them, Special Relativity predicts that we should see their clocks ticking more slowly (see the Special Relativity lecture). Special Relativity predicts that the on-board atomic clocks on the satellites should fall behind clocks on the ground by about 7 microseconds per day because of the slower ticking rate due to the time dilation effect of their relative motion [2].
Further, the satellites are in orbits high above the Earth, where the curvature of spacetime due to the Earth's mass is less than it is at the Earth's surface. A prediction of General Relativity is that clocks closer to a massive object will seem to tick more slowly than those located further away (see the Black Holes lecture). As such, when viewed from the surface of the Earth, the clocks on the satellites appear to be ticking faster than identical clocks on the ground. A calculation using General Relativity predicts that the clocks in each GPS satellite should get ahead of ground-based clocks by 45 microseconds per day.
The combination of these two relativitic effects means that the clocks on-board each satellite should tick faster than identical clocks on the ground by about 38 microseconds per day (45-7=38)! This sounds small, but the high-precision required of the GPS system requires nanosecond accuracy, and 38 microseconds is 38,000 nanoseconds. If these effects were not properly taken into account, a navigational fix based on the GPS constellation would be false after only 2 minutes, and errors in global positions would continue to accumulate at a rate of about 10 kilometers each day! The whole system would be utterly worthless for navigation in a very short time.
The engineers who designed the GPS system included these relativistic effects when they designed and deployed the system. For example, to counteract the General Relativistic effect once on orbit, the onboard clocks were designed to "tick" at a slower frequency than ground reference clocks, so that once they were in their proper orbit stations their clocks would appear to tick at about the correct rate as compared to the reference atomic clocks at the GPS ground stations. Further, each GPS receiver has built into it a microcomputer that, in addition to performing the calculation of position using 3D trilateration, will also compute any additional special relativistic timing calculations required [3], using data provided by the satellites.
No. It would be from the past. Unless the transmisdion was somehow done using pairs of entangled particles in which case it would be live until you ran out of them or they underwent decoherence.
Thnx
I have a better question...
Exactly how do jet engines propel space craft in a vacuum?
I don’t think there is a jet engine typical.
It is liquid fueled I believe...
If you achieve the speed of light which is quite impossible your will never receive a reply least you slow down to less than the speed of light. However that is not “gonna” happen unless you are on the Stare-ship Enterprise that defies all known physics.
I personally think our galaxy and universe is full of life. Only physics is the reason we do not have contact today. In the advance of science we only came out of caves 20,000 years ago. Other species are without doubt out their with science millions of years beyond ours. They have not contacted us because simple physics of interstellar travel make it impossible. As our science becomes better we may well detect their electromagnetic transmissions. I would suspect they are thinking the same thing, “are we alone.”
But even more sad would be a species that knows they are not alone and does not really give a damn as we are so far beneath them to be nothing but strange curiosities.
Nice
Thrust is not possible in a vacuum.
We used to have a message board called “FTL” (Faster Than Light) on one of the Sacramento Citadel (and other) BBS’s back in the 1980’s. All us smarter than everyone else teenagers would go on and on about how much we THOUGHT we knew about physics and try to outdo the other young brains full of mush that thought they knew more too. Ah, those were great days.
Think rockets and forget about jet engines once you get to the edge of the earth’s atmosphere. High flying aircraft like the SR-71 and U2 just barely get by, and they have specialized engines and body styles that let them still get lift and thrust at those altitudes.
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