Has Earth been visited by aliens?

[Joolee1980]

Some people think it has and i wondered what evidence there was for this.

[Old_Geezer]

There may have been no cars, but the physical laws still existed.

To overcome the problem with light speed you either have to prove our understanding is wrong, or find a way to appear to travel faster than light without actually travelling at light speed.

[R1Geezer]

who says? Anyone with an ounce of understanding of the scale we are talking about. Mathmatically life elsewhere is certain, look up the law of large number. Physically the distance involved is too vast to cross even at c. The earlier discoveries and achievements must have seemed surprising when they where made but reverse engineering them reveals how they work, we can comprehend why things worked with hind sight and we can ascertain the limits.

I accept that there is much to be discovered and I'll be the first to eat my hat but I consider myself a good layman in Physics (partical and astro), quantum theory, etc and I can't see us ever communication with aliens.

Jake, our resident nuclear physicist, what's your take on this?

[MarkRae]

> There may have been no cars, but the physical laws still existed.

Yes they did, including the ones we still don't know about...


> To overcome the problem with light speed you either have to prove our
> understanding is wrong, or find a way to appear to travel faster than light without
> actually travelling at light speed.

Absolutely correct. If not, then you'd have to believe that our current scientific knowledge is as good as it's ever going to get, and that nothing new will ever be discovered or invented. At which point, you may as well give up...

[jake-the-peg]

I can see the possibility of communication with aliens if the probability of life arising is sufficiently high that we can find someone to talk to in a radius of say less that 50 light years.

I can't see us ever meeting and the conversation is likely to be one where each generation gets in old age to receive a reply to their message when young.

There is some chance that we might discover a way to communicate faster than light, there are some hints in terms of quantum entanglement - I'd say the odds were against it but it might be worth an outside punt.

Personally travelling in that way is a very different kettle of fish though and I can't see that fitting in with what we already know to be good sound science.

I'd not yet agree about the mathematical certainty of other life - I'd think very highly probable but as yet we don't know enough about how life formed and we only have one example.

The probability of life might be more astronomically small than we can imagine but from the point of view of the living it would look more likely.

However given how quickly life came about on Earth I'd tend to believe that is not the case.

Find one other independant life creation event though like fossils on Mars and you'd have to conclude that it's very very common indeed

[Old_Geezer]

Just because one thinks understanding will increase it doesn't follow that, that ensures everything we presently believe will prove to be incorrect. Belief in light speed travel is pure optimism at the moment.

[MarkRae]

> what we already know to be good sound science

But that's the whole point! Only a few hundred years ago good medical science would have revolved around the calculation of the patient's astrological chart and trying to figure out which one of the four humours was out of balance with the other three...

If you close your mind to the possibility that everything we know currently is wrong, then there really is no possibility for technological advancement...

[Backdrifter]

Isn't it most likely that our first contact with extraterrestrial life would be with bacteria-like beings?

[R1Geezer]

No mark, doctors and scientists had to pretend to believe the mumbo jumbo, religious or otherwise to earn a living but learned men knew what was hppenning. They just couldn't say so, QED Galileo.

[pilotlight]

Whats the betting that they would have British passports if they did land on earth ?

[glen-d]

yes

[BBBE99]

This seems like a right geeky thread.
We sound like old ladies huddled up drinking tea over a coffee-table.
I want to be the one who wears the fleece (As I imagine it)...

[glen-d]

machu pichu peru

[Backdrifter]

Geeky? Why?

[jake-the-peg]

I disagree Mark.

Most advances of that type have been around the edges where the science wasn't sound.

Example- Newtonian Gravity was good enough to explain pretty much everything but there were some anomolies around stuff like the orbit of mercury etc. We needed General Relativity for that - Newton was good enough to send men to the moon but Breaks down when Gravity gets really really strong.

Likewise there are strong hints about where current science needs changing - dark matter - may well be sorted in the next couple decade or two, Dark energy is harder. But these are areas that are unlikely to help us in breaking the light barrier at least physically.

Quantum entanglement however shows effects travelling faster than light - this can be demonstrated now. It doesn't seem to allow information to be carried faster than light but it's not a big step to suppose that some modifications to this might be discoverred - a loophole if you like.

Remember though that faster than light travel is the same thing as time travel into the past and there are a number of logical paradoxs that spring up in that

[R1Geezer]

yeah backdrifter, they'll arrive in very small space ships no doubt!

[dustypuss]

http://www.cartoonsto...directory/A/Alien.asp

[chakka35]

jno, what you describe is not evidence of alien visits. All that these anecdotes claim is that peope have seen things in the sky which they cannot identify. The leap from that to spaceships is preposterous.

Statistically the probability of life elsewhere in the universe is very high. Equally statistically the idea that any of that life would be able or moved to visit this tiny rock orbiting a medium-sized star in the vast Milky Way which is just one of thousands of millions of galaxies in that universe is laughably small.

As others have said, there is no evidence of alien visits.

[joggerjayne]

The notion that there is no other life in the universe if preposterously naive ...

... (unless you adhere to a rigid "Creationist" dogma).

The idea that any of them has visited Earth is not definite ...

... but, statistically, is more likely than not.

[R1Geezer]

if time and space are infinite then anything possible is a certainty. It's arguable whether faster than light travel is possible.