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renerob
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Is it possible to conceive of a universe which had a beginning but is spatially infinite?
renerob said:Is it possible to conceive of a universe which had a beginning but is spatially infinite?
renerob said:Is it possible to conceive of a universe which had a beginning but is spatially infinite?
Dmitry67 said:Poetry is in another section of this forum I believe.
Dmitry67 said:Correct. There is nothing to prove.
Start from putting a list of experimentally verifiable predictions.
Otherwise it is just pure lyrics.
Dmitry67 said:Poetry is in another section of this forum I believe.
LoreSpade said:... Past Present Future and Anti-past, anti-present, anti-future. ...
The Graviton is in the http://lhc.web.cern.ch/lhc/News.htm" . Space is not a particle/energy/force – it’s just space.LoreSpade said:We have not found a particle for gravity. and i don't think a particle for space has been found.
9.81 m/s2 = at free fall the speed increases by about 9.81 meters per second every second = you must accelerate, or else you go down.LoreSpade said:So how fast would one have to travel without accelerating to leave the pull of Earth's gravity?
Dmitry67 said:... I believe most of the physicists believe in Block Time, except the minority, like Smolin. So, first of all, there is no "flow of time", anti-blah blah, pulling to something.
DevilsAvocado said:Does Block Time violate the thermodynamic arrow of time and/or the causal arrow of time?
Dmitry67 said:... The only non-trivial case is closed time curve, in such cases Novikovs self-consistency principle should apply ...
Dmitry67 said:... for some weird reason you won't be able to kill ...
Peter Watkins said:Re. #2. If our universe is the result of a collapsing previous universe, then that universe had sufficient gravity to occasion the collapse. If that universe did not come into being in it's expanded form, then it too must have expanded outward. Therefore, collapse of our own universe is inevitable, preceded by slowing, which will cause the galaxies to move apart at an accelerating rate.
Dmitry67 said:... just a trajectory in curved spacetime ...
LoreSpade said:... Furthermore if the past started with just one particle, and it moved into the future to be shot out by an Anti Future, ...
DevilsAvocado said:I think you’ve missed some very crucial facts. According to Einstein’s Special Relativity there is no universal Now, thus – there is no universal past and future in the Universe.
All we have is our local frame of reference.
So, who can decide what is 'now' in the Sun-scenario, you or me?
- If you and I would stand one meter from each other, and try to wave simultaneously (you’ll start), it will work very well, since it takes light 3.3 nanoseconds (one billionth of a second) to travel one meter.
- If I would travel to the International Space Station, it could also work pretty well, if we had a very good telescope each, since it takes light ~ 0.0011 seconds to travel 346 km.
- If I would travel to the Moon and repeat the experiment, with even better telescopes, it becomes a little more troublesome, since it takes light 1.3 seconds to travel 384,400 km. You’ll think I’ve lost some of my reaction.
- If I could travel to the Sun, with extremely better telescopes each, the experiment will become stupid. You would think I was drunk or asleep, since it takes light 8.3 minutes to travel 150,000,000 km. I on the other hand would think this is super-cool, since I can see we are waving simultaneously...
And it becomes even 'worse' – with observers moving at different velocities, report different distances, passage of time, and in some cases even different orderings of events!
If I was in the midway inside a speeding traincar, and you where standing on a platform as the train moves past, and I flash a light at the center of the traincar just as we pass each other. This is what will happen:
From my frame of reference onboard the train, the light will reach the front and back of the traincar at the same time.
You standing on the platform, sees the rear of the traincar moving toward the point at which the flash was given off and the front of the traincar moving away from it. As the speed of light is finite and the same in all directions for all observers, the light headed for the back of the train will have less distance to cover than the light headed for the front. Thus, from your frame of reference on the platform, the light will strike the back of the traincar before it reaches the front!
Now, who can decide what is 'now', and in what order things happens in the train-scenario, you or me!?
The physical world is 'complex' as it is – we don’t need to make it 'worse' by wondering about a philosophical 'Anti Future' etc...
LoreSpade said:... Instead of observing each other we are going to transfer energy. our tool is a uncuttable string ...
DevilsAvocado said:I admit: Many years ago I was thinking along the same path – what if one could build a 'railway' to the Sun, in the very stiff chemical compound Tungsten carbide, and take a BIG hammer a hit one end? Surely this will overtake the speed of light!? And I could send FTL-Morse messages to the Sun!
The answer is no no no no no NO!
Even more fundamental then our local frame of reference is the speed of light.
In vacuum NOTHING exceeds The Speed of Light 299,792,458 meters per second, not even the light itself, period.
There will be a wave of motion (actually one molecule 'bouncing' the next) in the Sun-'railway', and this motion can never overtake the speed of light.