Are we alone in the Universe?

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Re: Are we alone in the Universe?




by Christophe » 04/06/17, 10:39

New theories: http://www.iflscience.com/space/hiberna ... -life-yet/

In French google translates this gives:

Scientists have proposed a rather interesting reason for why we haven't found strangers yet, a problem known as the Fermi paradox (if life is so abundant, where is everyone?). They suggest that intelligent extraterrestrials could be in hibernation, waiting for the universe to get colder so that they can be more productive.

This idea was proposed in the Journal of the British Interplanetary Society, with a pre-print available on arXiv. The journal was written by Anders Sandberg, Stuart Armstrong and Milan Cirkovic of the Institute for the Future of Humanity at the University of Oxford, and was recently picked up by Gizmodo.

Some people think that a much more advanced civilization than ours could become a digital race. That is to say, they will live in artificial intelligence inside computers, removing more limited charnable bodies. Experts, including Elon Musk, have suggested that this is a logical progression into the future.

If we are not alone in the universe (which we have no proof of yet), we could therefore propose more than an advanced foreign race could have descended in this way. But to get the most out of their new digital bodies, they might not like the universe right now.

The temperature of the universe at this time is 3 degrees Kelvin above absolute zero. It's quite cold, but this temperature will continue to drop as the universe grows. Sandberg and his colleagues say that the temperature in the future could allow 1030 other computer processes than is currently possible.

"So we suggest a 'topical hypothesis,'" the researchers write in their journal, adding that "the reason we don't observe manifestations of extraterrestrial civilizations is that they are currently (most of the time) inactive, patiently awaiting future cosmic epochs ". Essentially is hibernation to avoid warmer temperatures, and not cooler ones.
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Re: Are we alone in the Universe?




by moinsdewatt » 04/06/17, 14:34

Future of Humanity Institute at the University of Oxford loves cold capillary traction
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Re: Are we alone in the Universe?




by Exnihiloest » 06/06/17, 17:45

Agree with lessdewatt on capillary traction.

Much more likely causes:
- we are the only ones
- the exploration of the universe does not impose physical displacements (compensated by discreet means of observation from a distance)
- the evolution of intelligent species leads to abandon the exploration of the universe for more interesting or more useful purposes
- the evolution of intelligent species causes them to annihilate or commit suicide before reaching galactic exploration capacity
- zoo theory: we live there and what we see of the universe is entirely controlled by higher intelligence
- ...

The first assumption is by far the most likely. Cosmological theories increasingly allow us to consider that our universe and its physical laws are only one among an immeasurable number of other universes with different laws. If there is a certain probability that in such universes the physical laws allow the appearance of observers, a universe with a single type of observer is more likely than two or more, and therefore we, Earth observers of our universe, we're just at the top of the Gaussian curve, which was statistically most likely.
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Re: Are we alone in the Universe?




by moinsdewatt » 06/06/17, 20:17

Or more simply:

Our "neighbors" did not come to see us because they are far too far.

And eventually if they tried they destroyed themselves along the way, a space route that takes thousands of years.
Humans are a little stupid, there is no reason why it should not be valid for other civilizations in other stars.
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Re: Are we alone in the Universe?




by Exnihiloest » 06/06/17, 22:26

moinsdewatt wrote:Or more simply:

Our "neighbors" did not come to see us because they are far too far.

And eventually if they tried they destroyed themselves along the way, a space route that takes thousands of years.
Humans are a little stupid, there is no reason why it should not be valid for other civilizations in other stars.


There is no distance limit for intergalactic exploration, because if we approach the speed of light, then the time of the traveler slows down, it is a consequence of special relativity.
Example:
We want to go to Alpha Centauri which is about 4 light years away. At a speed close to the speed of light, it would take us about 4 years to get there.
True ?
No, wrong! 4 years is the duration of our trip seen by those who stayed on earth. But for us, in our spaceship, the time t 'will be equal to t * √ (1-v² / c²) where v is our speed. If we go at the speed of light minus 1 millionth, instead of the 4 years seen from the earth our trip will last 4 * √ (1-999999² / 1000000²) = 0,0056 year = 2 days.


There is no limit in principle, we can theoretically go from one "end" to the other of the universe in an arbitrarily short time, well almost because the expansion of the universe somewhat thwarts our project. but this is another problem and anyway billions of galaxies are still accessible.
So although far, very far, very very far, if our neighbors have the technological advance that allows the approach of the speed of light, they can come to see us.
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Re: Are we alone in the Universe?




by sen-no-sen » 06/06/17, 23:47

The displacement could even be instantaneous via a "wormhole".

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Re: Are we alone in the Universe?




by izentrop » 07/06/17, 00:18

A Gallic adage said: "with ifs, we would put Lutetia in an amphora."
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Re: Are we alone in the Universe?




by Christophe » 07/06/17, 10:27

Exnihiloest wrote:There is no distance limit for intergalactic exploration, because if we approach the speed of light, then the time of the traveler slows down, it is a consequence of special relativity.
Example:
We want to go to Alpha Centauri which is about 4 light years away. At a speed close to the speed of light, it would take us about 4 years to get there.
True ?
No, wrong! 4 years is the duration of our trip seen by those who stayed on earth. But for us, in our spaceship, the time t 'will be equal to t * √ (1-v² / c²) where v is our speed. If we go at the speed of light minus 1 millionth, instead of the 4 years seen from the earth our trip will last 4 * √ (1-999999² / 1000000²) = 0,0056 year = 2 days.


I trust you on the formula (thank you by the way I did not know it and I thought it was more complicated *) but according to what I had learned it is AMHA the opposite: time slows down well when we are approaching the speed of light but travelers to Proxima will have to stay on the journey for 4 years "in their time" ... otherwise that would mean that in "ship time" we can greatly exceed the speed of light ( ?!?).

In other words it is not the time of the traveler which slows down but that of the observer which accelerates ...

And by applying the formula: each "2 vessel days", 4 years will pass on earth ... when they will have arrived (4 years in vessel time) it will have happened on Earth: 365 * 4/2 * 4 = 2920 years ... and ditto for all points at the same speed as the Earth. This will also pose trajectory forecasting problems as well! : Mrgreen:

Do I love myself?

In short for the moment, we are blocked on Earth and well blocked!

* this formula assumes that the speed of the "fixed" point is negligible I presume?

ps: you have to undergo 1G acceleration for a little less than a year to reach the speed of light. Order of magnitude to have in mind .... then do not forget to brake : Mrgreen: In short, it is bad to go for a walk in the stars : Cheesy: : Cheesy:
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Re: Are we alone in the Universe?




by Christophe » 07/06/17, 10:30

moinsdewatt wrote:Or more simply:

Our "neighbors" did not come to see us because they are far too far.

And eventually if they tried they destroyed themselves along the way, a space route that takes thousands of years.
Humans are a little stupid, there is no reason why it should not be valid for other civilizations in other stars.


I believe this theory :)

By the way, the famous "Wow" signal (which I never understood lol), would have been solved, it was a comet ...

extra_large-1496765233-cover-image.jpg
extra_large-1496765233-cover-image.jpg (29.61 KB) Viewed 2311 times


http://www.iflscience.com/space/the-wow ... f-a-comet/
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Re: Are we alone in the Universe?




by Exnihiloest » 08/06/17, 00:13

Christophe wrote:I trust you on the formula (thank you by the way I did not know it and I thought it was more complicated *)

Yes it is simple, it is the "Lorentz transform" for the time. But here we are in special relativity. If gravity intervenes, it is necessary to appeal to general relativity, and it is not cotton at all ...

but according to what I had learned it is AMHA the opposite: time slows down when you approach the speed of light but travelers to Proxima will have to stay traveling for 4 years "in their time". ... otherwise it would mean that in "ship time" we can greatly exceed the speed of light (?!?).
In other words it is not the time of the traveler which slows down but that of the observer which accelerates ...

And by applying the formula: each "2 vessel days", 4 years will pass on earth ... when they will have arrived (4 years in vessel time) it will have happened on Earth: 365 * 4/2 * 4 = 2920 years ... and ditto for all points at the same speed as the Earth. This will also pose trajectory forecasting problems as well! : Mrgreen:

Do I love myself?


Yes, regarding the time spent in the ship. It is explained there: https://fr.wikipedia.org/wiki/Dilatation_du_temps.
The time depends on the benchmark where it is measured. When we measure it in our own benchmark (the earth for earthlings, the ship for travelers), the one where our speed is zero compared to this benchmark, we call it clean time.

When we measure "at a distance" the time of events in another reference frame, it is necessary to make corrections to find the proper time in the other reference frame, from the time that we measure in our own measurement frame.
This is where the Lorentz transform of the time Δt = ΔΤ * (1 / √ (1-v² / c²)) comes in, where Δt is the time measured in us from something "at a distance" and ΔΤ the proper time of that something. I therefore used ΔΤ = Δt * √ (1-v² / c²) to obtain from the time Δt of 4 years measured by the earthlings, the proper time of the vessel, that the traveler lived, ie 2 days.

The principle of relativity is that you don't know who's moving. There is no absolute speed. The travelers see the earthlings move away from them at the same speed as the earthlings see the travelers move away. It's perfectly symmetrical.
What will create asymmetry is the return, because then the speed cannot be constant for the one who turns around. If the travelers make a U-turn, on their return they will have lived 4 days since their departure from earth and the earthlings them, will be 8 years older.

We can still deal with the problem in the context of special relativity although there are U-turns therefore non-constant speed, provided we make some assumptions (especially at the start, we consider that the travelers are already at almost speed c), otherwise you have to go through general relativity, brave have done it, and they find the same result as with special relativity (phew! :D ).

Note that this has been verified experimentally, it is not cinema, I say it for those who believe that we are in science fiction. We know the lifespan of certain radioactive atoms. By projecting them at high speed into a particle accelerator, we notice that their lifespan increases in accordance with the predictions of Einstein's relativity.

...
ps: you have to undergo 1G acceleration for a little less than a year to reach the speed of light. Order of magnitude to have in mind .... then do not forget to brake : Mrgreen: In short, it is bad to go for a walk in the stars : Cheesy: : Cheesy:

which means that a realistic journey at the speed of light will have to last at least two years if one does not want to undergo a painful acceleration of several g ...
But hey, we can also hope to find the trick for anti-gravity (therefore anti-acceleration). There is work ...
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