CycleChat Ivestigates - Alien Life

[Baldy]

When I lived in North Wales I often came across people who had met someone who knew someone who had seen things that could not he human

There was always a far higher incidence of UFO sightings in that area that other parts of the country



Remind me again where the busiest Air Force base in the UK is???

Sheep-dip does really bad things to the brain.

 

[ebikeerwidnes]

Sheep-dip does really bad things to the brain.

Given that this is North Wales we are talking about

is "sheep dip" a euphemism??

 

[Baldy]

Given that this is North Wales we are talking about

is "sheep dip" a euphemism??

No, I mean actual Sheep dip! yes we are talking North Wales.

 

[gbb]

I havnt read all the posts so may have been covered...
Closest star ? Proxima Centaurii ? Over 4 light years away. Assuming you could travel at the speed of light, scientists say to fly there and back...you'd arrive back here thousands of years later. I dont understand how that works but...we will never travel that distance, let alone further, sometimes hundreds or thousands of times further, and return to tell.anyone what they saw.
That's the closest, everything else is an extraordinarily amount further way.
I dont think humans will ever set eyes on (significant) alien forms. Microbial life in our solar system perhaps...its all just TOO vast

 

[Ming the Merciless]

Over 4 light years away. Assuming you could travel at the speed of light, scientists say to fly there and back...you'd arrive back here thousands of years later. I dont understand how that works

This will blow your mind even more. If you want to get back to Earth sooner, you need to travel slower.

 

[markemark]

Closest star ? Proxima Centaurii ? Over 4 light years away. Assuming you could travel at the speed of light, scientists say to fly there and back...you'd arrive back here thousands of years later. I dont understand how that works but...we will never travel that distance, let alone further, sometimes hundreds or thousands of times further, and return to tell.anyone what they saw.

I'm not sure I quite understand why, maybe something to do with the acceleration and deceleration? I'm not sure that time given is correct but happy to be educated.

However that will certainly be massively reduced by using robots rather than humans where g forces are less of a concern. Also no need to food, water, living space, oxygen, gravity deprivation equipment etc etc etc. Hence why it's very unlikely we'll ever meet aliens, only robots.

BBUUUUTTTTT, if you could travel close to the speed of light, then the time elapse for the humans on board will be substantially less and it all gets a bit confusing and Einsteiny as it might only be a few days for them, but thousands of years for us observers.

 

[DRM]

What if it's not aliens, but humans from way in the future, who can time travel, trying to save the human race from itself

 

[Dogtrousers]

What if it's not aliens, but humans from way in the future, who can time travel, trying to save the human race from itself

Ha! Good luck with that one, future humans.

 

[Ming the Merciless]

I'm not sure I quite understand why, maybe something to do with the acceleration and deceleration? I'm not sure that time given is correct but happy to be educated.

Time dilation, though you can’t reach the speed of light if you have mass, as it’d require infinite energy. Time is relative and has to dilate in order for the speed to light to remain constant for every observer.

 

[sungod]

Closest star ? Proxima Centaurii ? Over 4 light years away. Assuming you could travel at the speed of light, scientists say to fly there and back...you'd arrive back here thousands of years later.

if you really could travel at light speed there and back, the time elapsed on board the ship would be zero, the time passed on earth would be 2x the distance in light years, c. 8.5 years

but, as far as we know, nothing with mass can reach light speed, though with enough energy you can get arbitrarily close, so they'd have to settle for a short time passing between departure and return

from your perspective, onboard time runs exponentially slower the closer they get to light speed (c)

from their perspective it's perfectly normal on board (because it really is perfectly normal)

at 0.87 c, you'd see their onboard clock running at about half speed compared to yours
at 0.9999 c it'd be taking over a minute for every one of your seconds

the bigger issue is they and their ship would be reduced to a thin smear by the acceleration to instantly get up to near light speed

having to do it at survivable acceleration makes the trip much longer

having enough energy to accelerate long enough to reach close enough to c is really difficult, that's the limiting factor - the biggest rockets we have can just about get something to the moon (and at nowhere near c)

 

[Drago]

Space and time are inextricably linked, and you can only have so much of one or the other at a given moment. The more space you covers, the less time you get and that episode of Emmerdale drags onn and ooooonnnnn...

 

[markemark]

Yep, I know all that. My question is why travelling at the sol will take 4,000 years for a star 4 light years away on the assumption we have the (impossible) technoliogy

 

[Ming the Merciless]

Feel free to do some maths

 

[sungod]

Yep, I know all that. My question is why travelling at the sol will take 4,000 years for a star 4 light years away on the assumption we have the (impossible) technoliogy

it won't, 4 light years at the speed of light, takes 4 years as seen by an observer at rest with respect to the traveller

 

[markemark]

If a star is 4 light years away, I take that to mean as an observer it takes light 4 years to get to me. Therefore if you 'could' travel at the sol, it would take 4 years for me as an observer on earth to watch them get there, but a matter of minutes/days/hours (how close to the sol) for the people on board.

So where does the 4,000 years come from?