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the anthropic principle,
or what if the universe was not the way it is

a briefing document

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what we are made of
the search for other earth-like planets
planet formation
the constants of nature
bibliography

 

It is fascinating to me how many things have to go right for us to be here to notice them!

Here are a few of them:

what are we made of

mainly hydrogen, oxygen, carbon, and nitrogen
“The matter within every living Earth creature mainly consists of just four chemical elements: hydrogen, oxygen, carbon, and nitrogen. All the other elements together contribute less than one percent of the mass of any living organism.”

the six most abundant elements in the universe
“The four elements that form the bulk of life on Earth all appear on the short list of the universe's six most abundant elements. Since the other two elements on the list, helium and neon, almost never combine with anything else, life on Earth consists of the most abundant and chemically active ingredients in the cosmos.”

the elements of earth
[...] “Earth is mainly made of oxygen, iron, silicon, and aluminum. Only one of these elements, oxygen, appears on the list of life's most abundant elements.”

“When we look into Earth's oceans, which are almost entirely hydrogen and oxygen, it is surprising that life lists carbon and nitrogen among its most abundant elements, rather than chlorine, sodium, sulfur, calcium, or potassium, which are the most common elements dissolved in seawater. The distribution of the elements in life on Earth resembles the composition of the stars far more than that of Earth itself [...] ”

the search for other earth-like planets

“Spitzer has discovered for the first time dusty discs around mature, sun-like stars known to have planets. Hubble captured the most detailed image ever of a brighter disc circling a much younger sun-like star. The findings offer "snapshots" of the process by which our own solar system evolved, from its dusty and chaotic beginnings to its more settled present-day state.

“Young stars have huge reservoirs of planet-building materials, while older ones have only leftover piles of rubble. Hubble saw the reservoirs and Spitzer, the rubble," said Dr. Charles Beichman of NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif. He is lead author of the Spitzer study. "This demonstrates how the two telescopes complement each other," he added.”

“ Rocky planets arise out of large clouds of dust that envelop young stars. Dust particles collide and stick together, until a planet eventually forms. Sometimes the accumulating bodies crash together and shatter. Debris from these collisions collects into giant doughnut-shaped discs, the centers of which may be carved out by orbiting planets. With time, the discs fade and a smaller, stable debris disc, like the comet-filled Kuiper Belt in our own solar system, is all that is left.”

The extrasolar planets page at NASA gives links to several current and planned missions to look for planets.to top of the document


planet formation

[The following is abstracted from the National Geographic, December 2004, pp.79 – 80.]
Computer models suggest that large planets (say like Jupiter) form first, the left-overs form into hundreds of smaller dry planets [planetoids] about the size of the moon, whence the process would stop.

But then a larger outer planet pulls the smaller planets into eccentric orbits, this then encourages the planetoids to crash into one another, forming serious planets like Earth.

A young star is too hot, and these planets end up without water. Water would be locked up in smaller clumps further out, but the Jupiter-like planet then causes some of these smaller clumps, later, to crash into an Earth-type planet. Still the giant planet is not finished, it then starts gathering up the remaining debris which might be liable to crash into your home planet!

So, next time you look at Jupiter, one of the brightest objects in the sky, see not a lifeless planet but a good part of why you have a useful place to live!

The Nat Geo article is also interesting in telling of how planet seeking outside our little solar system is going, and the techniques being used:

  • Using double telescopes helps to cancel out the over-whelming glow of the suns, so that the planets around them can be seen.
  • Choosing a nearby sun (star) as a reference point to work out atmospheric distortion to cancel it out.
  • And failing there being a nearby star, sending up a laser beam to use as a false planet
  • Various space-located telescopes are planned so as to be able to planet-seek outside the distorting atmosphere of the Earth.

The human monkey gets trickier every week!to top of the document


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the constants of nature

There is a fascinating book by John D. Barrow, perhaps my favourite science writer. In The Constants of Nature, he explores recent ideas that life, the universe and all that sort of stuff could not have formed if several very basic constants, such as the speed of light and Planck’s constant, were not very close to their known values.

I would need to learn a lot more physics to believe I could really follow Barrow into some of the details, but my interest in reading his book was more general. However, The Constants of Nature may be a useful introduction for those focussed on some very basic concerns of recent physics. It was certainly worth the effort for me to plough through the book, when seeking to gain an idea of where physics thinking is going.

Barrow is a good teacher, but I imagine the grasp on this strange idea is not yet fully worked out, hence some muddiness and obscurity spiced with speculation!

I was particularly impressed with the discussion and conditions for ‘resonance’ (pp.154 – 156, NY edition) suggesting that, with remarkably small differences in the strong nuclear force and the fine structure constant, there would be no carbon! But this is far too difficult for me to explain, I’d have to re-read parts of the book several times, and a lot of background as well, to feel I had a fair grasp on the details of the argument.

However, the book is an interesting and fun read if you want to get some idea of investigations in this area. I spent good money on it, read it right through and feel I got my money’s worth.

Recommended Three and a half GoldenYak (tm) Award

marker at abelard.org

So, not only does the chemistry of our bodies look very convenient, and the formation of planetary system looks convenient, but so do even some very basic constants of the universe.

This is one exceedingly strange and wonderful place into which we’ve been pitchforked!

to top of the document


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bibliography

The Constants of Nature: From Alpha to Omega—The Numbers That Encode the Deepest Secrets of the Universe
by John D. Barrow

Jan 2003, Pantheon Books, NY, hbk,0375422218 $18.20 [amazon.com]

2002, Jonathan Cape, hbk, 0224061356, £12.59
Aug 2003, Vintage, pbk, 0099286475, £6.39
[amazon.co.uk]


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