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Galactic Survey: The Universe Dying as Old Stars Fade Faster Than New Ones Are Born
astroengine writes: A study of more than 200,000 galaxies, encompassing wavelengths of light from the far ultraviolet to infrared, shows that the universe is producing half as much energy as it did 2 billion years ago and continues to fade. "Newer galaxies are simply putting out less energy than galaxies did in the past," astronomer Mehmet Alpaslan, with NASA's Ames Research Center in Mountain View, Calif., told Discovery News. In other words, astronomers, for the first time, have gathered observational evidence that our universe is slowly marching toward its eventual heat death (in a few trillion years time).
"Heat," in an atomic sense, is basically a measurement of how constrained molecules are within a structure and how rapidly they're bouncing around. "Cold" molecules are those that arelocked into a rigid structure and don't move around much. "Hot" molecules are ones that move about freely, without constraint. In that sense, the "heat death" of the universe will be when there is no more solid matter in the universe, and all of its atoms are distributed evenly, bouncing around freely.
Karma: Terrifying (mostly affected by atrocities you've committed)
Time dilation isn't proven, otherwise we wouldn't have been able to see anything.
What are you babbling about? The GPS system has detailed time dilation compensation built into it. It's not only proven, it has to be accounted for in the engineering of a functioning system in worldwide use.
GPS satellites are moving at 14,000 km/hr relative to Earth's surface, a Special Relativity time dilation of 7 microseconds per day. But Earth-based clocks are deeper in the gravity well of Earth, so they suffer a General Relativity time dilation of 45 microseconds per day. The nanosecond accurate clocks on board the satellites are pre-calibrated before launch to tick more slowly than they should while on Earth, so once in orbit, they tick at a General-Relativity-time-dilation-compensated rate that then matches Earth clocks. The software still has to compensate for any additional, unpredictable drift caused by orbital variances.
Time dilation is quite real, and must be accounted for, or GPS and Galileo wouldn't work at all. Uncompensated clock error amounts to 10km on Earth per day.
Time dilation isn't proven, otherwise we wouldn't have been able to see anything. Now the doppler shift is quite true, but that is not time dilation.
Time dilation has been directly observed by carrying atomic clocks from one place to another, both via planes and satellites. It has also been observed in particles via their halflife.
Then you are not moving at all. Speed is distance travelled over time.
You don't observer your own time being dilated, as your clock always appears to go the same speed. However you will observe length contraction, so the distance will have changed. As your speed increased relative to your destination, e.g. Alpha Centauri, then the distance will appear shorter by whatever observation methods you have within your frame. With 1 g acceleration, you can get to Alpha Centauri in ~2.3 years in your frame, as the distance will contract as your frame changes. To an external observer in the original frame, they would not see the distance change, but instead see your clock slow down in a completely consistent way, so it still looks like 2.3 years elapse on the ship to the external observer too.
If it takes you roughly 4 years to travel from Earth to Alpha Centaury you are traveling with the speed of light
That depends on who's clock you are using. If the person on Earth measures it as four years then yes you are correct. However if you are using the clock onboard the ship then a 4 year trip means that you are only at a fraction of light speed. The difference is that for you the distance between AC and Earth is less than 4 light years due to length contraction. Were you actually to travel at (almost) light speed the trip would take almost no time at all and, for you, AC and Earth would be almost no distance apart.
Special relativity is the most accurately tested scientific law that there has ever been. Every particle accelerator uses it - not just the LHC but the machines in the basement of hospitals to treat cancer and make medical isotopes. Cosmic rays would not exist in their observed form (muons would decay too fast) without time dilation and it has been seen using atomic clocks on Concorde. Time dilation might be an extraordinary claim but it is supported by extraordinary and overwhelming evidence.