Is the universe filled with intelligent life? Possibly not.

Started by René, September 07, 2019, 09:07:27 am

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Matt

Our rate of expansion out into the universe will be limited by c. But because of time dilation, individuals or groups of people will be able to choose to travel long distances in a relatively short amount of time in their frame of reference. The price they'll pay is watching everyone they know who is still planetside age and die. Groups of people will separate themselves from the rest of humanity not only in space but also in time, but we could spread out across the whole galaxy this way.
Just because milk is white doesn't mean that clouds are made of milk.

N-drju

These are indeed good points. A ship appearing to take forever to reach the speed of light, would be consistent with time dilation rules - the faster you go, the slower the time flies in another frame of reference. But that doesn't mean said ship is not speeding up.

By the way, acceleration and relativistic speeds are not about "magic". Shrinking ship and a ship that, paradoxically, slows down as it accelerates is just a question of how light is being reflected off such an object.

Precisely because of that, you will not even be able to see an FTL object because its image (meaning the light it reflects) would reach you far long after the object has already passed by!

But... we're sort of diverging from the main topic of this thread which was an ET life...

For one thing, I think that it is impossible to believe that ET have already visited us accepting, at the same time, the notion that FTL travel is completely impossible. Otherwise, how would they even reach us in the first place?
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

Matt

Quote from: N-drju on September 09, 2019, 04:34:57 pmFor one thing, I think that it is impossible to believe that ET have already visited us accepting, at the same time, the notion that FTL travel is completely impossible. Otherwise, how would they even reach us in the first place?

They don't have to travel faster than light to travel large distances in a short amount of time in their relativistic frame. A being could travel hundreds of light years in just a few years as they perceive it and be completely consistent with the laws of physics as we know them. We could do the same, but we will need to build propulsion technology that generates high acceleration that can be sustained for long periods of time. It can be done even with just 1G of acceleration as long as that can be sustained for a few years. We don't need any magical FTL technology to do this.
Just because milk is white doesn't mean that clouds are made of milk.

Matt

Just because milk is white doesn't mean that clouds are made of milk.

Dune

Your remarks just opened my eyes a bit further. Forgetting that light from something is not a 'real' thing, it's just light. But still it feels physically incorrect to 'see' people you leave behind die so fast, but I guess you can't really see it either, as it's only their light that lets us 'see' it.
Something to ponder again....

N-drju

Quote from: Matt on September 09, 2019, 05:04:19 pmThey don't have to travel faster than light to travel large distances in a short amount of time in their relativistic frame. A being could travel hundreds of light years in just a few years

Of course, you are right! How could I forget about it. But this only proves how many things need to be taken into account to determine or rule out an existence of intelligent life in space. I seriously don't think that any scientist has a luxury of having thought patterns like we do.

A race with enough knowledge and level of development could probably also use wormholes for travel. By the way, an object the existence of which the special theory of relativity explicitly supports.

@ Ulco - To confuse you even further, take a look at how you would witness a superluminal object passing next to you. An effect caused solely by the light bouncing off of it. You would never even be able to see it's actual form.

https://upload.wikimedia.org/wikipedia/commons/6/64/Tachyon04s.gif
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"


René

I am not an expert on the theory of relativity, far from it, but as I understand it time is stretched to infinity at the speed of light and comes to a standstill. So the 300 thousand kilometers per second that is measured is only the relative speed, for photons there will be no time passing and distances are reduced to zero.
Although all this is counter intuitive and I do not understand the underlying mathematics, I have no reason to doubt the theory of relativity; it has been tested many times. Geostationary satellites that control the navigation equipment in cars need to be calibrated at regular intervals because the clocks are lagging behind those on the earth.
Of course I can be completely wrong because I am not an expert. ;D


T

René

Does light experience time?

https://phys.org/news/2014-05-does-light-experience-time.html

If you still have doubts, watch this film, if you haven't already done so, and everything will become clear. :D

Interstellar https://www.youtube.com/watch?v=0vxOhd4qlnA

N-drju

Quote from: René on September 10, 2019, 05:10:07 amInterstellar https://www.youtube.com/watch?v=0vxOhd4qlnA
Been there, done that. :P

https://planetside.co.uk/forums/index.php/topic,23534.msg238195.html#msg238195

As for the photons not experiencing time, I find this idea fascinating. Would that mean that by just achieving "c" we could travel through space forever, not age even one second and not even experience distance as such? How would such a travel look like? Earth, snap, Andromeda Galaxy. Slideshow instead of a travel?

Of course you would definitely wish to take your relatives and friends with you!
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

René

You wouldn't travel at all and there wouldn't be any distances, just an eternal now, I guess. I can't imagine how one would experience that. For me the whole concept of relativity is already mind-boggling.
That's one of the most frightening moments in the film you've depicted, by the way.

archonforest

I would like to know how time can slow done or stop? Technically time is not existing. Time is a representation of change in the physical universe. Earth changes its position around the Sun and this movement is translated into "time". But there is no time itself. It is just an agreement between humans that this amount of movement/change equals 24 hours. Time was needed to have stable data between people and to lessen the chaos.
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N-drju

I think that the theory of relativity actually explains that time is a physical value, though I agree with you - how??

I'm also curious about one thing... If, as the eggheads say, time slows down to "0" as you approach the "c" speed... does it mean that by crossing the "c" speed one can actually travel back in time...? ??? It's a logical conclusion.
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

Matt

You can't push past c, so there is no possibility of reversing time. To travel at the speed of c in an external reference frame, you travel at infinite speed in the moving frame. No matter how much faster you try to go beyond infinity, you are still travelling at the speed of infinity. To the external viewer this appear to be c. So it's impossible to go faster than this.
Just because milk is white doesn't mean that clouds are made of milk.

N-drju

Quote from: Matt on September 10, 2019, 02:40:38 pmYou can't push past c, so there is no possibility of reversing time. To travel at the speed of c in an external reference frame, you travel at infinite speed in the moving frame. No matter how much faster you try to go beyond infinity, you are still travelling at the speed of infinity. To the external viewer this appear to be c. So it's impossible to go faster than this.

Y'know, I prefer trigonometry thank you very much.
:P
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"