– So what happens if I shine two torches in opposite directions? Aren’t the photons moving away from each other at twice the speed of light from my perspective? (This is the part of SR that I’ve not come to grips with yet — thankyou for your continued patience).

– It all depends on our definition of habitable… if there is liquid water under the surface of Europa, it doesn’t sound entirely beyond our capabilities to adapt to living there. With respect to goldilocks zone planets in other solar systems within 20 light years of here: our abilities to detect them are still in their infancy, so not having found any yet is a far cry from saying that none exist.

– Communicating with extraterrestrial life is a whole other can of worms :-D Considering the ratio between the time that there has been life on Earth, and the time that we have been able to try to communicate with extraterrestrial life, it seems to me that having another similarly technologically advanced life form in that same tiny proportion of time, close enough to have picked up mankinds EM emissions, and replied is vanishingly small. Even if the universe is teeming with bacteria, daffodils, cockroaches and crocodiles!

To “answer” your question, yes, it’s impossible, due to the mentioned spacetime distorting effects of SR.

I don’t think that we’ve found any habitable planets that are 20 to 30 light years away, nor do I expect it, since we haven’t heard from anybody that’s less than 100 light years away… assuming that they are equally developed, technologically… which is what the goldilocks enigma predicts will be the case.

Practically, I think the best contribution I can make is to evangalise the possibility of mankind as a spacefaring species, in the hope of sending out ripples in the pond of public interest. The more public interest in the space programme we have, the more media coverage it will get, and the more likely an increase in budget and scope of projects we will see.

Do you have any other ideas on what impact we can make on the status quo?

Cheers, Gary

Also, time dilation effects might make travel to the nearest stars feasible. Gradual acceleration to half the speed of light, and then turning around half way to decelerate would certainly make travel to a stars 20 or 30 light years from here achievable in an astronauts lifetime. Actually, something I never quite understood in relativity is this: motion is all relative except for a the always constant speed of light, but for arguments sake we invent an engine that can reach 51% of the light speed; if two such engines set off in opposite directions, effectively each will see the other moving away at 102% of light speed… but that’s impossible isn’t it?

Are you saying that if big business stopped pulling in one direction, that the green movement is a runaway variable that left unchecked could spell the end of humanity?!?! I don’t buy that at all. While there are certainly social and economic pressures that can have enormous impact on our environment, it’s an gigantic leap to link them to the survival of our species. But maybe you’re just likening the change of manifest physical constants over time to Green Peace versus Apple, Inc.?

Practicallity… Can you travel faster than light, because you’ll need to, in order to get to another habitable world, since the physics predicts that you cannot make one habitable that isn’t in the goldilocks zone. While the biosphere proved that we haven’t got a chance in hell of any kind of “batttlestars galactica” scenarios, much less, an outpost on a moon or another planet that doesn’t rely on the Earth for reprovisioning.

Rather than trying to comprehend what you guy’s are arguing about, i think i’ll just suggest this:

What we should be doing is thinking about what we can practically do to bring these ideas into reality, rather than dwelling on the what if’s. :)

http://www.salon.com/books/feature/2007/07/03/pauldavies/indexnp.html?source=rss

My current thinking is that the anthropic principle explains why we live in a universe with so many finely tuned parameters, especially considering that so many of them are required for the basics of life

Right, the idea is to identify from first principles why the universe is configured in a completely unexpected manner that points at carbon based life.

An energy conservation law, for example, (which is my own understanding).

although the concept of them changing independently with time is new to me.

Careful, I was talking about features of the goldilocks enigma that evolve into being over time, like our local ecobalance, for example. I don’t think that the contants have to change “independently” in order for that the happen.

But the struggle between the green movement and big business represents one of these precarious anthropic balances, so you’re missing the local application that prevents us and other things from killing us off. The illustration that I referred correctly depicts the balanced between diametrically opposing runaway tendencies that lead to certain death if the balance could be tipped.

Which means that you should only get nervous when we AREN’T surrounded by gloom-n-doom certain death scenarios.

Again thanks for the links, there is much food for thought there. My current thinking is that the anthropic principle explains why we live in a universe with so many finely tuned parameters, especially considering that so many of them are required for the basics of life, although the concept of them changing independently with time is new to me. Even so, while I can’t refute any of what you say without more research on my part, even if I take your statement about everything only being temporarily aligned at only this moment in time in that manner which permits life as we know it at… there’s still nothing to stop humans from becoming extinct due to one of the many reasons I alluded to, even when those parameters are still in the right alignment. Living on multiple planets (preferably in different parts of the galaxy, but lets not get ahead of ourselves) is still our best insurance policy against ecological/cosmological/over-population disaster on Earth. And no amount of cosmology or philosophy can make that any less true!