Growth and energy: for Stephen Hawking, Earth will be a Fireball in 2600 ...

[Christophe]

It will not be so easy Mr Hawking, one more obstacle (as if it were necessary ...) to the alien colonization by humanity: http://www.pourlascience.fr/ewb_pages/a ... -38948.php

The brain, forbidden from space travel

Experiments on mice show that cosmic radiation destroys neural connections and degrades cognitive performance. A more serious obstacle than previously thought for manned interplanetary travel.

For millennia, men have looked at the sky and dreamed of traveling to the stars. Now that some have walked on the Moon and sometimes spent several months in orbit on the International Space Station, it seems inevitable that we will try to go further: Mars, the rest of the Solar System, or even beyond. This dream is shared by many cultures and occupies the space agencies of several nations.

And yet we know that space is a hostile environment. Whenever astronauts leave Earth, they are faced with extreme cold, the absence of an atmosphere, microgravity and exposure to cosmic radiation. These dangers have so far been considered to be surmountable: primarily problems that engineers are doing their best to address and risks that brave space travelers are willing to take. But several teams, including mine, have recently shown that radiation in space could be more harmful than we thought, especially for the human brain, a fragile yet essential organ. Researchers have suspected such an impact for decades, but it is only recently that we have had concrete evidence of the full extent of the effects of cosmic rays on the brain.

By subjecting mice to radiation comparable to that to which astronauts are exposed in space, my colleagues and I observed significant and lasting cognitive impairment, which would probably be found in humans and potentially jeopardize the success of space missions. Yes the astronauts of the International Space Station, which is in relatively low orbit (about 400 km above sea level), are to a large extent protected by the Earth's magnetic field, the risk for travelers to Mars and beyond is much more serious.

Our ability to reduce these dangers to astronauts is currently limited. By improving the shielding of spaceships, we could stop some of this deleterious radiation, but no known material is both light enough to be transported into orbit and effective in protecting astronauts. And we are only in the very early stages of developing drugs that can combat the effects of radiation inside the body. Unless we find a solution that really works, the human dream of traveling in the Solar System and beyond could forever be out of reach.

Constant cosmic bombardment

Cosmic radiation is pernicious: we can neither see nor feel it, and yet it fills every cubic centimeter with what appears to be empty space. However, it can cause significant damage in biological tissues. The greatest danger for astronauts is that of cosmic rays of galactic origin, mainly ionized atomic nuclei (88% hydrogen, 9% helium, traces of heavier elements, but also photons) which are move at a speed close to that of light. They are probably produced and accelerated in the supernovae, violent explosions of stars at the end of their life.

To these galactic cosmic rays which permeate the cosmos in an almost uniform way, we must add the particles of the solar wind and those of the coronal mass ejections during solar flares. These particles (mostly ions) are expelled at speeds of between 300 and 800 km per second for the solar wind, and up to 2 km per second during coronal mass ejections. Less energetic than galactic cosmic rays, they are however more numerous.

Whether of solar or galactic origin, these particles have enough energy to pass through the hull of spaceships and the bodies of astronauts. On Earth, the planet's magnetic field protects living organisms by deflecting most of these cosmic particles, which do not reach the ground. It extends up to around 60 km altitude on the side of the Sun and stretches much further on the "night" side. Thus, travel beyond this magnetosphere (the Moon is for example located nearly 000 kilometers from Earth) inevitably leads to increased exposure to cosmic rays and their interactions ...

[Christophe]

So I see 2 solutions for traveling in space you have to send brainless men there!

So either gametes or artificial intelligences (with or without transfer of consciousness ...)

But it is not at all certain that artificial intelligences are not impacted by this radiation ...

[izentrop]

There is also the Vavilov-Cherenkov effect which prevents sleep http://secouchermoinsbete.fr/67392-des- ... mir?page=3
But hey, it's nothing compared to all these particles that travel in space and that go through you through damaging cells and DNA in the process.

[Christophe]

and DNA by the way.

Yes, so not even that the gametes arrive unharmed ... after that it is surely easier to protect 1 million gametes than a single adult man ...

Now remains to resolve the question of time

[sen-no-sen]

So either gametes or artificial intelligences (with or without transfer of consciousness ...)

But it is not at all certain that artificial intelligences are not impacted by this radiation ...

AI remains the most logical option, for what transfer of consciousness is another story, what is consciousness?
If we make a duplicate of myself it does not actually transfer anything at all and will not jeopardize my experience of death if necessary, hence the transhumanist scam on this subject.

[Christophe]

Stephen Hawking left us this morning ...

If it had lasted a few more decades, I think we could have considered a transfer of consciousness ...

"Stephen Hawking boasted of being born on January 8, the date of Galileo's death. He died on March 14, the day of Albert Einstein's birth", laughs Geoffrey Compère, researcher in theoretical physics at the Free University of Brussels, after the announcement on Wednesday morning of the death of the British astrophysicist.

Three hundred years separate the death of the Italian physicist Galileo and the birth of Stephen Hawking in 1942, in the United Kingdom.

The Briton bowed his bow on a new biography on Wednesday since March 14 saw the birth of the father of the theory of general relativity, which Hawking upset in the 1970s.

The astrophysicist has left a lasting mark on the scientific world, in particular thanks to his information paradox, which opposes the laws of quantum mechanics to those of general relativity. "With this paradox, it contradicts a theory of microscopic mechanics which wants information never to be lost", explains Geoffrey Compère. "If I use a metaphor that Stephen Hawking used to explain himself, it's like throwing the Encyclopedia Universalis into a black hole. The black hole gradually evaporates and eventually disappears with all the information contained in the Encyclopedia. "

Indeed, "before Hawking, we thought that black holes were immutable; however, they evaporate", adds physicist Christophe Ringeval of UCL. "In a vacuum, they emit elementary particles and eventually disappear, as if you left a glass of water on a radiator without ever filling it. The matter, water in this example, evaporates until the last drop. "

"Thanks to his qualities as a popularizer, he has thus succeeded in transmitting to the general public his fascination for the beauty of physics", concludes Mr. Compère.
BELGIAN

http://www.lalibre.be/actu/sciences-san ... 0c1a4e8237

[izentrop]

Nicolas Martin talked about it this morning https://www.franceculture.fr/emissions/ ... -mars-2018.
He will have been a great vugarizer of physics and a great astrophysicist, but "over the last years of his life he has somewhat tarnished the image of the scientist and the importance his research may have brought to astrophysics and to cosmology ".

[brinbrin62]

The Starshot breakthrough project is just a DIY. Ambitious DIY, but DIY. No chance he would go beyond school. No sensible person would want to embark on a journey of decades, even in hibernation. Far too much risk. And psychologically ...

At the limit if the Alcubière engine (a Star Trek warp drive) could one day, vaguely, let glimpse the possibility of the shadow of a feasibility, I would be seduced so much I want to.

But any technology based on the principle of reaction propulsion (I push on one side, it advances on the other) is doomed to failure for interstellar travel.

Furthermore, it is not said that our species exceeds this century. If the runaway climate is confirmed, the world population will be greatly reduced. If oil runs out, there is no more intensive farming. A combination of the two and 95% of humanity passes through it. Yes, yes, 95%.

Paul Chéfurka's article "World energy and population - Trends up to 2100" (http://www.courtfool.info/fr_Energie_et ... diales.htm) is instructive on this subject.

[Christophe]

For those who want to know Hawking better.

A brilliant researcher but heavily paralyzed, the British theorist is, contrary to the image one likes to give of him, the antithesis of the lonely scientist armed with the sole power of his brain.

https://www.pourlascience.fr/sd/sociolo ... e-8320.php

[Christophe]