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Author Topic: Will the Universe continue to expand forever?  (Read 12230 times)

Offline PhysBang

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Will the Universe continue to expand forever?
« Reply #25 on: 04/11/2009 15:27:20 »
You are spot on. Space is not empty of matter and photons will hit stuff. When this happens they will inevitably lose energy, but only in the form of wave lenght.
When a photon hits something, it is absorbed, not reduced in energy and not transformed in wavelength. We can actually see the results of this in astronomical observations.
 

Offline litespeed

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« Reply #26 on: 04/11/2009 17:09:40 »
Pys - You are right, I was thinking of something else.

Assuming a photon is completly annihalated, all of its energy will have been transformed into something else. Examples are electricity and chemical energy (photsynthesis) and heat. And even a photon of radiant heat is probably a whole new one.

But what I have been pondering lately is the proposal to use solar sails for long distance travel at high speed. The sail would be propelled by massive objects emited by the sun. However, the scenario I heard include reflecting sun light. That scenario seemed to imply photons have momentum, and when reflected will transfer that to the sail. If that is true, the only way it could be done is if the photon is reduced in frequency.

Just babbling....







 

Offline litespeed

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« Reply #27 on: 06/11/2009 20:25:09 »
Vern - You wrote: "I suspect the probability that life exists in other systems is more probable than we suspect..."

Two things. First, am skeptical there are very many mathematically capable creatures in the universe, judging from my own experiences with mathematics. However, I have been following the Drake equation for a very long time now.  At the time Drake had very little data to plug into his formula.  I think he predicted 19 advanced civilization in our galaxy right now. Then came nothing but a series of bummers.

As far as I can recall, the actual data we have gathered since was unfavorable in each and every case. Further, we found variables he did not include that are spectacularly negative. The REALLY big one is the moon. Not only do we need a goldie locks orbit, but we need a goldie locks moon as well. And the chances to produce the moon we have are WAY bad. I mean orders of magnitude bad.

Then it turns out our gas giants are more important then he figured. Specifically, they are in the outer system, and act as giant hoovers protecting us from otherwise marauding stuff like comet Schumaker Levie

In addition, we have now found about 300 planets, mostly gas giants.  It is one thing to say we just do not yet have the technology to detect earth like planets. It is entirely another thing to note the hundreds of gas giants found just about preclude any earthling type creatures in those systems. It turns out that all or almost all of the gas giants orbit close, even VERY close to their respective suns.

In otherwords, they would hoover up anything in the goldie locks zone anyway!



 

Offline Vern

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« Reply #28 on: 06/11/2009 20:35:48 »
Yes; the chances are slim earth like systems. I suspected the probabilities would be greater if the only requirement for life was a self replicating entity. Something like that might even be in the innards of a star. :)
 

Offline litespeed

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« Reply #29 on: 06/11/2009 20:41:55 »
Vern - You also wrote: "... I doubt that we'll ever meet up with any extra terrestrial sentient beings. Distances are too great, unless there is some as yet unknown means of communication."

In this respect I have better news. I speculate entangled particles can be used for instanious communications once we detect them being sent out. Specifically, as an advanced and curious civilization I send out alternating strings of entangled and non entangled particles.

The advanced receiving civilization recognizes the difference, and manipulates the entangled sets thus sending instantaneous communications to the sender. Of course, the particles might have been sent millions of years ago. But if this works, it would instantaneously connect us to any network of such communications already established.

Further, it is entirely possible for sentient creatures to travel way beyond the speed of light.  [See my thread on time dialation].  Of course, it is something of a one way trip, and by our observations it would have taken them WAY WAY longer to get here then they experinced.

Still, if the human race lasts long enough to where it really really needs to get out of town, even intergalactic trips are possible. Just add enough energy to the space vehicle, and you can slow time down to near zero while the ship itself is traveling near the speed of light.  Of course space is not empty, and traveling at such speeds might require actual Startrek type force fields to keep it from burning up.

But what the hell, its all speculation anyway!
 

Offline litespeed

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« Reply #30 on: 06/11/2009 20:49:30 »
Vern

I am once again running out of beer and will shortly retire for the day. However, I believe organic life of lower orders is entirely possible in extreme environments. It is the mathematically capable life that will be in short supply. 

Even earth, with its magical orbit and magical moon never produced a mathematically capable dynosaur even after tens of millions of years. Further, our own mathematically capable people [not me] almost didn't make it. Recent genetic research suggests our species was climatically reduced to no more then a couple of thousand individuals not that long ago.

Specifically, there is more genetic diversity in a single Chimpanzie troop then all of human kind.

Cheers!
 

Offline Vern

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« Reply #31 on: 06/11/2009 21:12:32 »
Quote from: litespeed
The advanced receiving civilization recognizes the difference, and manipulates the entangled sets thus sending instantaneous communications to the sender. Of course, the particles might have been sent millions of years ago. But if this works, it would instantaneously connect us to any network of such communications already established.
Well; we can hope; but so far we have been unable to communicate anything via entangled particles. Each experiment so far has not given enough evidence to determine whether the observed entangled particle assumed its observed state at the time of entanglement or at the time of manipulation --- observation. I've been paying attention to that, so far no cigar. :)
 

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Will the Universe continue to expand forever?
« Reply #31 on: 06/11/2009 21:12:32 »

 

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