UFOs and Aliens corner

[TimberWolf]

Travelling at 0.99c, which would be needed to get anywhere in a reasonable time, there'd be no time to avoid small dust particles, and at that speed they'd have a huge kinetic energy. Also, dust and gas is fairly uniform in our galactic neck of the woods.

The only way to cope with it IMHO would be to use a high-tech "cow catcher", travelling independently a couple of million miles in front of the spacecraft.

This would be something like a mile-wide disk comprising an ultra-thin (monoatomic) self-repairing nanoscopic mesh of carbon bucky tubes. When a dust particle hit this, the particle would be instantly converted to plasma, which could then be diverted or collected by magnetic fields. If this was designed right it would sweep out a near perfect vacuum for the main spacecraft following.

(The net would need to be a monatomic layer so that it would only graze the particles, which would mean only localized damage to the net and the particles would turn to plasma behind the net - A dust particle travelling at 0.99c has literally the kinetic energy of a mountain, and if it impacted a solid object most of that energy would be released as heat, which would punch a huge hole in the object.)

You'd also need separate provision for larger objects (anything larger than a pebble). But these are pretty rare in interstellar space - gas and microscopic dust particles are the main problem there.

That's a huge volume of space to be swept out by a cow catcher being hit by particles travelling near c, and which presumably is being further retarded by background radiation (which is no longer uniform in the direction of travel). How does it stack up when the numbers are crunched?

[Addanc]

Odd that people only started seeing flying saucers after they appeared in Hollywood movies..........

Pilots were allegedly seeing "foo" fighters (UFO) during WWII. The only sci-fi that I can think of that pre-dates this is Flash Gordon and Superman; not really the sort of flying saucer movies you are hinting at.

The biggest pointer to the non-existence of flying saucers is a complete lack physical evidence.

[Addanc]

Why the aliens travel in odd shaped flying objects
Haven't they studied aerodynamics ?

Only need aerodynamics if you are reliant on an interaction with atmospheric gases to keep you in the air.

[Clippy]

Seems appropriate to post this.

[TimberWolf]

It is highly improbable that humans will ever explore beyond the Solar System http://www.universetoday.com/2008/08...ience-fiction/

I like the reader comments there alluding to the fact that science advances so we can't predict now what might be come up with in 20 years, let alone in humanity's entire lifetime. As if the laws of physics can be advanced in the same way computers get better every year

Yeah, in 50 years time breaking the speed of light will be child's play compared to today, current physics will have been long superseded.

[TimberWolf]

The end of Physics was predicted at the end of the 19th Century... it was all known apparently.

Then the quantum effect was discovered...

Keep banging the rocks together, monkeys, you'll get there in the end...

I blame the black monolith.

Advances in technology and the fundamental laws of physics are separate things and increased knowledge of the fundamental laws may further diminish what we think we can achieve, rather than increase it

[DaveB]

If they existed, they'd be here by now.

The Fermi paradox is a conflict between an argument of scale and probability and a lack of evidence. A more complete definition could be stated thus:

The apparent size and age of the universe suggests that many technologically advanced extraterrestrial civilizations ought to exist.
However, this hypothesis seems inconsistent with the lack of observational evidence to support it.

The first aspect of the paradox, "the argument by scale", is a function of the raw numbers involved: there are an estimated 250 billion (2.5 x 1011) stars in the Milky Way and 70 sextillion (7 x 1022) in the visible universe. Even if intelligent life occurs on only a minuscule percentage of planets around these stars, there should still be a great number of civilizations extant in the Milky Way galaxy alone. This argument assumes the mediocrity principle, which states that Earth is not special, but merely a typical planet, subject to the same laws, effects, and likely outcomes as any other world.

The second cornerstone of the Fermi paradox is a rejoinder to the argument by scale: given intelligent life's ability to overcome scarcity, and its tendency to colonize new habitats, it seems likely that any advanced civilization would seek out new resources and colonize first their own star system, and then the surrounding star systems. As there is no conclusive or certifiable evidence on Earth or elsewhere in the known universe of other intelligent life after 13.7 billion years of the universe's history, it may be assumed that intelligent life is rare or that our assumptions about the general behavior of intelligent species are flawed.

The Fermi paradox can be asked in two ways.

The first is, "Why are no aliens or their artifacts physically here?"

If interstellar travel is possible, even the "slow" kind nearly within the reach of Earth technology, then it would only take from 5 million to 50 million years to colonize the galaxy. This is a relatively small amount of time on a geological scale, let alone a cosmological one. Since there are many stars older than the sun, or since intelligent life might have evolved earlier elsewhere, the question then becomes why the galaxy has not been colonized already. Even if colonization is impractical or undesirable to all alien civilizations, large scale exploration of the galaxy is still possible; the means of exploration and theoretical probes involved have bee discussed extensively. However, no signs of either colonization or exploration have been generally acknowledged.

The argument above may not hold for the universe as a whole, since travel times may well explain the lack of physical presence on Earth of alien inhabitants of far away galaxies.

However, the question then becomes "Why do we see no signs of intelligent life?"

A sufficiently advanced civilization could potentially be seen over a significant fraction of the size of the observable universe. Even if such civilizations are rare, the scale argument indicates they should exist somewhere at some point during the history of the universe, and since they could be detected from far away over a considerable period of time, many more potential sites for their origin are within our view. However, no incontrovertible signs of such civilizations have been detected.

There are a large number of counter arguments to the Fermi Paradox, none of which completley account for the absence of evidence for extra terrestrail life.

To sum it up, if they existed, they'd be here by now.

Hi ZG

[TimberWolf]

Long lived large fast flying objects (bigger than say a proton) seem to be rare or non-existent in nature. I don't mean distant or galaxy sized objects, which clearly do approach superluminal velocities wrt Earth, I mean we don't see, say, pebble sized objects that have been ejected from distant cosmic events hurtling past us or into the Moon. I wonder if they are slowed down by the instellar medium?

[AlfredJPruffock]

The apparent size and age of the universe ...

So the whole premise of the Fermi Paradox is based upon the apparent size and age of the Universe.

Well then - how old is (this) Universe and what size is it - I wont go onto to enquire how many universes there are - for now.

[DaveB]

The apparent size and age of the universe ...

So the whole premise of the Fermi Paradox is based upon the apparent size and age of the Universe.

Well then - how old is (this) Universe and what size is it - I wont go onto to enquire how many universes there are - for now.

From the post above... ( lifted from wikipedia btw, "other sources of information are available." )

...there are an estimated 250 billion (2.5 x 1011) stars in the Milky Way and 70 sextillion (7 x 1022) in the visible universe...

...13.7 billion years of the universe's history...

Even if you think the Universe(s) are bigger and older or more numerous than this it reinforces the argument made by Fermi and others.