Reply to: UFO Proliferation

[Diver]

Mass Hysteria Rules

[HairyArsedBloke]

Blimy, another one!

[Marina]

It's also hard to speculate on the Fermi paradox when we don't even know where 90% of the matter in the universe is! Early days.

I think physicists know pretty much *where* most of it is. They just don't know *what* most of it is.

baryon ("ordinary") matter that we're made of and radiation makes up only 4% of mass/energy. So called dark matter makes up 22%, and the remaining 74% is uniform dark energy which drives cosmic expansion.

So in a way we and all we can see are simply froth on some murky bulk of material and energy whose nature is still an almost complete mystery.

[TimberWolf]

Also we wouldn't waste energy pumping it out uselessly into the cosmos. Advanced civilisations will be invisible from more than a few light years away.

It's also hard to speculate on the Fermi paradox when we don't even know where 90% of the matter in the universe is! Early days.

[HairyArsedBloke]

I dispair sometimes... you lot haven't even found dilithium yet...

Come on, get on with it...

I don't want to be stuck here for ever.

They already have; it was ages ago. It’s a conspiracy by the big oil companies to hide it so as to protect their profits. You lizards should know that. After all, it’s you lot that are behind it all.

[TheBigYinJames]

100 million years needs a heck of a lot of imagination though! Why would these being want to roam? Why mine, surely elements could be manufactured from other matter or from energy?

Also we wouldn't waste energy pumping it out uselessly into the cosmos. Advanced civilisations will be invisible from more than a few light years away.

[TimberWolf]

Fermi Paradox specifies sub-light speed travel. It is the time-scales involved that raise the paradox.
Use a mind-game. Imagine the human race in 100 million years time. Would we still be pottering about on planet Earth messing with computers and stuff? No. We have I guess 100 stars within 20 light years, most with planetary systems. They'd be colonised, at least by mining colonies. And the 10,000 stars within 20 light years of those? Them too. Imagine our energy / signal output, it would be hard to miss even from 1000 light years away.
So the time has been there but we see nothing. And personally, if I try to visualise the human race in 100m yrs, I don't see it happening. In fact I'm stretching to see us around in 200!

100 million years needs a heck of a lot of imagination though! Why would these being want to roam? Why mine, surely elements could be manufactured from other matter or from energy?

[TimberWolf]

Like he says, so long as you change Planck's constant and the charge on the electron too then everything would be the same, but that wasn't what was speculated.

Anyway, I've often wondered why c is so low. It puts a limit on technological development and as noted quarantines the various star systems off from each other. Maybe that is the plan. Perhaps we should have a word with the great maker to get it changed?

I was more interested in avoiding having rewriting physics to accommodate a change in light speed since just on philosophical grounds I believe it would make no difference. If it were 'less', relativistic affects would appear 'earlier', distances would 'appear' longer and so if the speed of light changed we wouldn't even know it.

A fixed speed of light is a philosophical interpretation of reality anyway, a postulate of special relativity. I imagine other interpretation are possible, though less useful.

[ace00]

The Fermi Theory is all well and good, saying "if there are so many lifeforms, why are they not here ?", but it completely ignores the fact that to travel to us in a meaningful timescale is beyond the laws of physics.

Fermi Paradox specifies sub-light speed travel. It is the time-scales involved that raise the paradox.
Use a mind-game. Imagine the human race in 100 million years time. Would we still be pottering about on planet Earth messing with computers and stuff? No. We have I guess 100 stars within 20 light years, most with planetary systems. They'd be colonised, at least by mining colonies. And the 10,000 stars within 20 light years of those? Them too. Imagine our energy / signal output, it would be hard to miss even from 1000 light years away.
So the time has been there but we see nothing. And personally, if I try to visualise the human race in 100m yrs, I don't see it happening. In fact I'm stretching to see us around in 200!

[HairyArsedBloke]

This Cambridge professor doesn't seem to think so:

...If c, h, and e were all changed so that the values they have in metric (or any other) units were different when we looked them up in our tables of physical constants, but the value of α remained the same

Like he says, so long as you change Planck's constant and the charge on the electron too then everything would be the same, but that wasn't what was speculated.

Anyway, I've often wondered why c is so low. It puts a limit on technological development and as noted quarantines the various star systems off from each other. Maybe that is the plan. Perhaps we should have a word with the great maker to get it changed?

[TimberWolf]

Well, ignoring the fact that if it was that low then it would prohibit the existence of matter in a form to build star and planets out of ........

This Cambridge professor doesn't seem to think so:

[An] important lesson we learn from the way that pure numbers like α define the world is what it really means for worlds to be different. The pure number we call the fine structure constant and denote by α is a combination of the electron charge, e, the speed of light, c, and Planck's constant, h. At first we might be tempted to think that a world in which the speed of light was slower would be a different world. But this would be a mistake. If c, h, and e were all changed so that the values they have in metric (or any other) units were different when we looked them up in our tables of physical constants, but the value of α remained the same, this new world would be observationally indistinguishable from our world. The only thing that counts in the definition of worlds are the values of the dimensionless constants of Nature. If all masses were doubled in value [including the Planck mass mP] you cannot tell because all the pure numbers defined by the ratios of any pair of masses are unchanged.
http://en.wikipedia.org/wiki/Variable_speed_of_light

[RichardCranium]

Diver's got a friend... Bless!

But of course. Nurse Gladys.

[HairyArsedBloke]

Use gravity wave generators to temporarily warp spacetime, sheesh.

Yeah, kids today. Always with it can’t be done. They should do what we did when we were young: get on our bikes and figure out how to make it happen.

I'm wondering what things would be like if the maximum speed were 30 mph instead of 300,000 m/s.

Well, ignoring the fact that if it was that low then it would prohibit the existence of matter in a form to build star and planets out of ........

[TimberWolf]

...Takes a bit of getting used to, but it's been verified in all kinds of ways.

I'm wondering what things would be like if the maximum speed were 30 mph instead of 300,000 m/s. I'm beginning to suspect it would be the same as now, but I havn't finished confusing myself about it yet. For instance time dilation would come into effect at sub 1mph speeds and there would be a cost to acceleration (increased mass etc), and your partner would have aged by the time you get home if you go too fast.

[expat]

Relativity

Einstein himself did say that the problem with relativity was not that it was hard to understand, but that it was hard to believe.

But it was experimentally established some 90 years ago.