Hi all

Am reading Rare earth at the moment and just wondering if anybody else has read it and what do they think of it...

Hi Trevor.

Have u a link for it?

Hi john

here is a link to it on amazon
www.amazon.com/Rare-Earth-Complex-Uncomm...7702-9382559?ie=UTF8

The Rare Earth hypothesis argues that the emergence of complex life required a host of fortuitous circumstances,but whos to say our model is the standard?

The emergence of the self-replicating DNA molecule (life) is still a total mystery.

One of the greatest scientific challanges is to figure out how that happened.

Anything that is said about it is guesswork still.

This much is scientifically true though:
"People are DNA's way of making more DNA".......Edward O. Wilson biologist.

The emergence of the self-replicating DNA molecule (life) is still a total mystery.

One of the greatest scientific challanges is to figure out how that happened.

Anything that is said about it is guesswork still.

This much is scientifically true though:
"People are DNA's way of making more DNA".......Edward O. Wilson biologist.

That's true but the rare-earth people say something much simpler. "Life on earth took ages to get going, if the earth had not been stable for so many millions of years it would not have evolved as far as us". They then ask "is that long-term stability the norm or something special". Turns out it seems quite special.

Oh ... actually ... I did a short 10 minute talk on this a while ago for a competition for science communication and I got second prize for it so it can't have been total rubbish! The slides are here: www.bartbusschots.ie/downloads/050330UniqueEarth.pdf

As it's only a 10 minute talk there's only about 10 slides so it's easy going

The emergence of the self-replicating DNA molecule (life) is still a total mystery.

One of the greatest scientific challanges is to figure out how that happened.

Anything that is said about it is guesswork still.

This much is scientifically true though:
"People are DNA's way of making more DNA".......Edward O. Wilson biologist.

Is life that great a mystery?
What is 'scientifically true' and is it better that alternative truth?
Could it actually be that DNA is peoples way of making more people.
(Perhaps he was only guessing!)

Socratically Yours

JMP

I like this quote from Carl Sagan:

"Some people think that if your granny feels uncomfortable there then life must be impossible."

Your slide show was actually saying that it must be like the Earth.

We really dont know if that is true.

Thanks for the responses, I am about half way through the book and TBH I find some of the authors reasoning a bit of a stretch, too many if's for my liking and not enough solid evidence.

But, I guess there is no proof no matter what side of this particular arguement you come down on.

"All living things are robots built for the regeneration and propagation of the DMA molecule."

"Reproduce the genes,the DNA" is the rule of all life.

That is the CORNERSTONE of all modern biology since Crick and Watson deciphered the double helix structure in 1953.

You were dragged into existance for that purpose,and when the DNA molecules have done with you you will die.
Know anybody over 150 ?

Life (DNA self-replicating molecules) was on the Earth less than 500 million years after the crust cooled.
It may be everywhere in the Galaxy.

We dont know, and your guess is as good as anybody elses.

DNA will figure large in discussions about getting to Mars and elsewhere.
Cosmic Rays cuts DNA to pieces.

There is no protection from Cosmic rays half way between here and Mars !

Where's Gondwaland?

Isn't that the name given to the land mass millions of years ago before it split into the Continents we have now?

It was actually called Gondwanaland, and was indeed the supercontinent that existed about 600 million years ago. It was one half, actually, of a duo of supercontinents - the other being Laurasia. The primary landmass was Pangea before the split.

S.

"You were dragged into existance for that purpose,and when the DNA molecules have done with you you will die.
Know anybody over 150 ?

Well, I don't personally know anyone over 95 but the oldest human age reached is 122.5 years. However, extensive research is ongoing into extending the human lifespan, such as stopping oxidative processes (oxygen free radicals cause a gradual deteoriation of tissue and cells), caloric restriction (eat less!), hormone treatment and gene manipulation. Researchers have already increased the lifespan of dogs by 20% using caloric restriction, and with gene manipulation, have increased the lifespan of mice by 50 to 75%. Unfortunately, at the moment, there's no such thing as a free lunch and most of this research leads to sterility or reduced fertility but it's a young science so I wouldn't put a limit on the human lifespan just yet.

DNA will figure large in discussions about getting to Mars and elsewhere. Cosmic Rays cuts DNA to pieces. There is no protection from Cosmic rays half way between here and Mars !

Most cosmic rays get stopped at the heliosphere, only the fastest get through to the inner solar system (those moving at +0.5c) so interstellar spacefarers will be at more risk. Cosmic rays do of course pose a threat to astronauts but those who landed on the Moon were exposed to cosmic rays and survived very well. The thickness of shielding necessary to stop cosmic rays precludes its use on spaceships but current reasoning is that exposure to cosmic rays on astronauts during a two year trip to Mars is likely to increase the risk of fatal cancer by a few percent. It's not cutting DNA to pieces.

Thanks for spotting the typo dmcdona.
Never spotted myself dropped the "na" typing Gondwanaland.
Why didnt U tell me before ?

Peter.

Just One trip Gorgdon!
Risk goes up a few percent !

After 5 years in that environment you and your DNA are cut to shreds.

One meter of lead shielding only serves to smash up the incoming protons to riddle you only even more efficiently.

Where does that leave Martin colonies except buried deep under the martian surface.

Who wants to live like that ?

(P.S. After my unspotted typo I've migrated to Pangea..easier to spell!)

Peter.

Just One trip Gorgdon!
Risk goes up a few percent !
After 5 years in that environment you and your DNA are cut to shreds.
One meter of lead shielding only serves to smash up the incoming protons to riddle you only even more efficiently.
Where does that leave Martin colonies except buried deep under the martian surface.
Who wants to live like that ? Peter.

Petger, there is a vast amount of ongoing research into how astronauts can be shielded against cosmic rays. NASA set up a working Group in 1995 and you may wish to have a look at the document published in 1997 titled "Shielding Strategies for Space Exploration" at: www-d0.fnal.gov/~diehl/Public/snap/meetings/NASA-97-cp3360.pdf
Due to weight, you can rule lead out as a form of cosmic ray shielding. There are more efficient methods being researched. One exciting research area is the use of superconducting magnet technology, in other words, creating a magnetoshpere to envelop the spaceship or habitat. Hybrid systems such as plasma shields (a combination of magnetic shields and electrotrostatic shields) are also being studied. Systems such as these could be even more effective if used with a solid mass shield.

I am quite optimistic that science and human ingenuity will eventually overcome whatever problems lie in the way of space exploration, including those pesky GCRs.

When you calculate the strength of those fields Gordon you find that the energy generated damages you as badly as the incoming radiation.

Where do you store the fuel to generate such collosal energy that it can deflect a proton from hitting your ship at 99.999999999 % of the speed of light.

Surround yourself with thirty feet of water and you are safe.

How do you do that in space ?

When you calculate the strength of those fields Gordon you find that the energy generated damages you as badly as the incoming radiation. Where do you store the fuel to generate such collosal energy that it can deflect a proton from hitting your ship at 99.999999999 % of the speed of light.

Best you discuss this with Dr Jeffrey Hoffman of MIT who is heading a NASA sponsored research team on shielding using superconducting magnets. This is of course just one avenue NASA are exploring; there are more conventional ones as well.

Surround yourself with thirty feet of water and you are safe. How do you do that in space ?

NASA are currently researching the feasibility of just such a scenario but using liquid hydrogen fuel as well as water.

Have a look at all the information freely available or maybe contact NASA for links to ongoing projects. Best of luck.