UFOs

[The Atheist]

Do not for an instant baulk at the thought that, by buying the books, you are funding a dangerous nutter. Nutters of Icke's calibre should be given as much money as they need to keep going. This stuff is so intricately, so unfalsifiably, so comprehensively insane that it beggars the creative imagination.

Oh, I agree he's completely harmless, but he has no need of our money.

He's about to undertake a speaking tour of NZ, for which tickets are $99, which just happens to be $10 more than premium seats for Walking with Dinosaurs, a show which costs about $2 million to stage.

Tickets for Icke are selling fast apparently.

I wonder if they have a tinfoil-hat stand?

[Lokasenna]

I wonder if they have a tinfoil-hat stand?

You could make one - take some of the money back!

I had only vaguely heard of David Icke until this thread encouraged me to go and look him up.

The man is a certifiable cretin, but you can't fault him for comedy value.

[Baudolina]

Wheras all that is true, were you to pace out the distance travelled, in a traditional earth dweller way, The distance would be the same, only the time taken would be in dispute. (I think) Is it legitimate to measure distance by the time it takes to cover it? It raises an interesting quandry about the relationship of time distance and speed.

No, from the point of view of the particle, the distance is way shorter and the time required for the trip is way shorter too. What is preserved, what people "traveling with the particle" (lol) and people on the earth agree on, is the speed of the particle. We think its speed is (huge distance divided by huge time) and it thinks its speed is (short distance divided by short time), but it works out to the same number.

The interesting thing about all this is that, with sufficient energy, you can complete a trip of any distance--no matter how huge--in some set amount of time, say one hour, from your point of view. So a person or alien can live through a trip of any length at all. 100 bazillion light-years? No problem for the people on the ship. The trouble is with the people on the home planet. Once the ship turns around and comes back home, it turns out that some obnoxious amount of time has passed, like one million years, etc. and not the few hours it seemed to those on the ship. This is why I don't see how Star Trek scenarios will ever be workable.

[billl]

Some physicists have had fun debating the possibility of one theoretical type of engine that seems to resemble the Star Trek Warp Drive.

http://en.wikipedia.org/wiki/Alcubierre_drive

There are some problems (and some guys trying to address them!), but the objections end up really piling up, it looks like. My favorite criticism mentioned in the Wikipedia article is the fact that the ship wouldn't be able to communicate with (influence) the area in front of the warp bubble, and it would therefore be impossible to control, steer, or stop the ship. But, basically, the main objections are about the energy required, and the problem of actually starting the thing (the warp wave, the bubble riding it).

[The Atheist]

Not sure where this original post is, but this is a good question:

Is it legitimate to measure distance by the time it takes to cover it?

That's just the way the numbers are expressed. The distance is actually expressable in km, but when the number is something like 4.5 trillion km, it's easier and more understandable that we use "5 light years".

Whether or not the speed of light is constant wouldn't affect the actual distance, which is every bit as measurable as the distance to the moon, or to the corner shop.

[Propter W.]

I believe in UFOs. They maybe unidentifiable to me, but to others they might be very well known. Perhaps they're simply unclassified. I don't automatically link the term UFO with extraterrestial life.

I do believe in alien life forms, however. Whether they are intelligent enough to know or even suspect we exist and have the means to visit us is a different question. It's not impossible, though. After all, we are able to travel to the moon, send unmanned 'spacecrafts' into space, etc. and we're a rather primitive species, to be honest.

[prendrelemick]

I suspect whoever wrote that was fooling with you.

Proxima Centauri is roughly 5 light years, or 47 trillion km distant.

To reach there in 50 years would need a speed of 10% of the speed of light.

Light travels at about a billion km an hour, so we would need to be travelling at 100,000,000 km/h.

Given that current technology only allows us to travel at ~50,000 km/h, we haven't got a clue as to what kind of propulsion might be needed to attain that kind of speed. You can't make rockets go faster by building them bigger, so it's impossible to put an energy value on the question. Whether humans could withstand being propelled 20,000 times faster than ever before is moot.

Even the escape velocity of the sun (sorry to pour cold water on Mr Spock) is a measly 2,000,000 km/h, still only 2% of the speed needed to get to Proxima Centauri in time for the half-century party.

It was indeed based on 10% of the speed of light, and didn't include deceleration. I think it was a thoroughly theoretical excercise.

[prendrelemick]

No, from the point of view of the particle, the distance is way shorter and the time required for the trip is way shorter too. What is preserved, what people "traveling with the particle" (lol) and people on the earth agree on, is the speed of the particle. We think its speed is (huge distance divided by huge time) and it thinks its speed is (short distance divided by short time), but it works out to the same number.

.

I can't quite get my head round this.