UFO Proliferation

[TheBigYinJames]

Where do you get your 3 months from ?

He's talking about time dilation. A 4 year trip might indeed feel as short as 3 months if you accelerate close enough to c, and time dilation kicks in. Or even less time if you can accelerate closer to c than 0.99.

Time on earth would be the same, though. 4 years would still have passed to those back on earth.

[Board Game Geek]

The Fermi Theory is all well and good, saying "if there are so many lifeforms, why are they not here ?", but it completely ignores the fact that to travel to us in a meaningful timescale is beyond the laws of physics.

[Bagpuss]

Or maybe they consider the human race about as important as a bogey up an old man's nostrel

[TheBigYinJames]

The Fermi Theory is all well and good, saying "if there are so many lifeforms, why are they not here ?", but it completely ignores the fact that to travel to us in a meaningful timescale is beyond the laws of physics.

It's not beyond physics, it would take a lot of energy for sure. Ship-time isn't a problem if you can get close to c, thanks to time-dilation. But when you got back home, people you know would have aged and died.

[Board Game Geek]

He's talking about time dilation. A 4 year trip might indeed feel as short as 3 months if you accelerate close enough to c, and time dilation kicks in.

So you are suggesting then, that on Earth, with our frame of reference, the light from the star appears to have taken 4 ly to get to us, whereas within the light's own frame of reference, it has only taken 3 months ?

What I am trying to say, is that a ship may indeed keep constantly accelerating, but it will never reach the speed of light.

Since it takes light 4 years to get here from the star, that is also the length of time a ship, that could theoretically travel at light speed, take to reach the star.

[TheBigYinJames]

So you are suggesting then, that on Earth, with our frame of reference, the light from the star appears to have taken 4 ly to get to us, whereas within the light's own frame of reference, it has only taken 3 months ?

No, since light has no mass and travels at exactly the speed of light, zero time passes for the photons. A fairly massive ship, accelerating constantly, would reach very close to the speed of light in a few months. Time dilation would start to happen, making time pass quicker for the people on the ship.

What I am trying to say, is that a ship may indeed keep constantly accelerating, but it will never reach the speed of light.
Since it takes light 4 years to get here from the star, that is also the length of time a ship, that could theoretically travel at light speed, take to reach the star.

From OUR frame of reference. To those on the ship, it will take less and less time the closer it accelerated towards the speed of light. If the ship got to 0.99 the speed of light, then the 8 year round trip (to us) would only have been 6 months to the people on the ship.

This is not whacky science fiction, it's real physica and has been proved experimentally, by measuring two atomic clocks, one on the ground, one on a plane speeding along. The clocks kept time at different rates. Even satellites have to be resynched every so often because of their speed which makes time pass faster for them.

[HairyArsedBloke]

Or maybe they consider the human race about as important as a bogey up an old man's nostrel

Why should they give a toss about the human race? There is plenty of potential for real-estate development on Earth. Developers on Earth have never given a dam about the locals, so why would anyone else be different.


If they are anything like New Labour when they took our jobs and homes away to give to foreigners as they took bribes, the aliens would say something like, “Not my problem; you’ll have to find somewhere else to live. You should have been more adaptable and made provision for this happening.”

[Board Game Geek]

This is not whacky science fiction, it's real physica and has been proved experimentally, by measuring two atomic clocks, one on the ground, one on a plane speeding along. The clocks kept time at different rates. Even satellites have to be resynched every so often because of their speed which makes time pass faster for them.

Thanks for explaining it, but it does sound definitely in the league of wacky ideas.

Ok let’s look at the following.

Voyager 1 is currently 106.027 AU away from the Earth. It is the furthest, still functioning human-made object from our planet.

It was launched in September 5th, 1977. Call it 31 years ago.

How far, in light years has Voyagrt 1 travelled in that time ?
0.0016765 of a light year.

So, 31 years to travel 0.0016765 of a light year.

Yet, according to time dilation, perhaps only x days, weeks or even months have passed “on board” the probe ?

It doesn’t feel right somehow.

Can we therefore supposed that all those 30 year old electronics, which are on the ship and subject to the same time dilation, have been subject to only a few weeks usage ? Either they have had 31 years of constant use, or 2 weeks. You cannot have both.

At the current speed, we’re still looking at about 60,000 to 90,000 years to get to Alpha Centauri, 4.3 ly away. Yet, time dilation suggests actually only 3 months have passed in total ?

Hmmm.

Supposed we send a telemetry request to the probe to ask for it’s current time and date ? What should we expect to get in return ? I would anticipate today’s date, to be honest.

Hmmm, I have heard of the process of observation “changing” the result. What happens, do the instruments gang up like a gaggle of politicians and conspire to produce their own “version” ?

Perhaps we should have a second pair of eyes in the probe, that is tasked with reading and storing the result in a format that cannot change, or if it does, a checkbit flags up, much like MD5 on pictures.

Then when we ask the second pair of eyes for the passage of time answer, we can see if the checkbit changes.

Interesting stuff eh ?

Thanks for a good conversation by the way. In spite of recent developments, this board and some of the posters are the real deal :-)

[TheBigYinJames]

Ok let’s look at the following.
Voyager 1 is currently 106.027 AU away from the Earth. It is the furthest, still functioning human-made object from our planet.
It was launched in September 5th, 1977. Call it 31 years ago.
How far, in light years has Voyagrt 1 travelled in that time ?
0.0016765 of a light year.
So, 31 years to travel 0.0016765 of a light year.
Yet, according to time dilation, perhaps only x days, weeks or even months have passed “on board” the probe ?

No, because it's not moving particularly fast. Not anywhere near the large fraction of the speed of light you have to be going before time dilation has a big effect. Time Dilation affects GPS satellites because they use timing to work out distances, and the small effects of time dilation can make several metres difference to these distance measurements. But for voyager which has travelled (given your figures) at about 10km a second for the last 30 years, this is only a fraction of the speed of light, so time dilation will be equally miniscule.

You have to get close to c to get time dilation.

[Board Game Geek]

Ah I C !

:-)

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