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The Universe Is Fine Tuned To Permit Humans To Exist Somewhere In It.

The laws of physics are "fine tuned" to permit intelligent life to exist somewhere in the universe. We have no idea why this is, and I say that that is the greatest unsolved scientific problem.

The universe around us began 13.7 billion years ago; we call this beginning the Big Bang. We have no idea how or why. We do know that it began very small, very condensed, and very hot. We have a lot of reason to suspect that this initial state was very very simple. It rapidly expanded, and thanks to that expansion it cooled. As it cooled, the complexity of present-day physics soon emerged: the four interactions, the up and down quarks that would in due course form all nuclei, the electrons enabling nearly all properties of matter including all chemistry, and the neutrino and photon bath all around us. We have no idea why the Big Bang resulted in equal amounts of positive and negative charge, namely two up quarks per down quark, and as many electrons as down quarks. We are still struggling to understand why the Big Bang gave rise to a slight excess of matter over antimatter, which is why the baryonic universe about us is made of matter but not antimatter.

The expansion of the universe was rapid enough to prevent a recollapse due to gravity. It was not so rapid as to prevent galaxies and stars from forming. We have no idea why the dynamics of our universe happen to be just right in this way.

Large stars end as supernovas, which are the pressure cookers in which all elements other than hydrogen and helium are made. Astrophysicists call these elements "metals." Without supernovas, rocky planets, water, and biochemistry are impossible. This nucleosynthesis requires that the fundamental laws and constants of physics be just right.

Most regions of our galaxy have too many energetic photons, or are poor in metals. Hence it is likely that life, especially life more complicated than microbes, is rare in the universe. But the amazing thing is that intelligent macroscopic life is at all possible anywhere in our universe. We still have no idea how life on Earth began, and how it apparently began within a few hundred million years of the cessation of the asteroid bombardment that took place 3.8 billion years ago. Some viruses are "coded" by RNA. All other living things are coded by DNA strands. We have no idea of how and why nature chose the coding system it did.

I date the start of the intellectual adventure this post touches on, with Newton's work in the 1660s. Much of our awareness of the perplexities posed by our fine tuned universe we owe to Dickey and Wheeler at Princeton, and to Dennis Sciama's students in the UK. This awareness is barely 40 years old.

The gentlest path to what this post has touched on is the popular books of Martin Rees. More challenging is

Davies, Paul (2006) The Goldilocks Enigma. Penguin.

Much harder yet, but also more rewarding, is

Barrow, John, and Tipler, F J (1986) The Anthropic Cosmological Principle. Oxford University Press.
consa consa 66-70, M 8 Responses Jun 13, 2010

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We are all the universe. We are all connected. Animals, insects, water, sand, material is all one. We all come from the same material. We are all a expression of god, god is all. God not a person, but the energy flowing from the cosmos!

Wow i never thought i would sound like the people i thought they were crazy lol. It's crazy to come to see that the impossible is actually possible. And that everyone person in this world is one whole.

If the Big Bang had been more energetic by about 1 part in 10^60, the universe would have few stars, no galaxies, and would consist mainly of diffuse cold clouds of hydrogen and helium.
If the Big Bang had been less energetic by about 1 part in 10^60, the universe would be mostly black holes. It would be shrinking now, and possibly have collapsed into one giant black hole.
Under both scenarios, complex matter is impossible. We in fact observe immense complexity, starting with the biosphere of our planet.
The electrostatic attraction of the proton and electron is 10^39 times stronger than their gravitational attraction. If the exponent is anything other than 39, nucleosynthesis and complex matter become impossible.
Why are the laws of physics such as to humour our planet and our species?
We simply don't know.

I appreciate that Feynman denied that the existence of our species is a crucial fact about the universe. Here's a quote taken from Dawkins's eulogy at Douglas Adams's funeral:

"... imagine a puddle waking up one morning and thinking, 'This is an interesting world I find myself in, an interesting hole I find myself in, fits me rather neatly, doesn't it? In fact, it fits me staggeringly well, must have been made to have me in it!' This is such a powerful idea that as the Sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, it's still frantically hanging on to the notion that everything's going to be all right, because this World was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise. I think this may be something we need to be on the watch out for."

You and many skeptics are impressed with Dawkins's words. I am not.

"Why are the laws of physics such as to humour our planet and our species?"
With respect... you have this round the wrong way... and it isn't actually a question.
i find no need to complicate an essentially simple universe by asking questions that arise only if we refuse to see that we are, well, puddles... surely that doesn't make me a sceptic

Since the death of Chris Hitchens, Dawkins has become the clear leader of the English speaking skeptic & atheist community. Douglas Adams was a proud member of that community. One of the hallmarks of scepticism is denying the that anything can be learned from the anthropic coincidences. Denying the possibility that our planet is unique in the Milky Way (the Rare Earth hypothesis).

My post and comments are intended to convey my puzzlement. But behind my puzzlement lies the following confident assertion: our universe is NOT simple. That is why physics and astrophysics are such grand human adventures.

Sorry, not my field in any way, but are you saying that because life exists, then the universe is 'fine-tuned' for that purpose?
i ask because, well, isn't that a fundamental error of reasoning?

Yup, isn't it around 100 billion stars in our little galaxy, and around 100 billion other galaxies? What a wonderful universe!
The periodic table is rich.
Carbon is gregarious.
Liquid water is friendly to complex chemistry.
Granting all that 'argumentum', well, so what? How does 'why?' come into it?
My mother and my father met... happenstance. They coupled (holding my hands over my ears and shutting my eyes and going 'nan nah nah nah don't want to think about it!) and one particular spermatozoon won the 'first to the ovum' race and i am the result. So what? It didn't have to be me until it was me (emphasis on those last four words).
What i'm saying is that my parents didn't meet in order to produce me. My grandparents didn't produce my parents in order to produce me. The billions of years of evolution on this planet didn't happen in order to produce me. The universe's 14 billion year history hasn't had my arrival as its point and purpose, no more than it has had our species as its point and purpose, and no more than it has had life as its point and purpose.
To look back, in hindsight, at the last 14 billion years and then say... 'Wow, it can't be just chance that all that came together to produce me!' is as great an error of reasoning as saying that the universe had the emergence of life as its 'point and purpose'. In fact, neither point nor purpose is needed. Given how the universe is, then life can develop. That much is obvious, because here we all are... the dogs, the plants, the crocodiles, the humans, the fleas and, most importantly for our planet, the bacteria. But so what? It didn't have to be as we see it now, and what we see now only becomes astonishing in hindsight. Let me emphasise that... only in hindsight.

Rather, the fundamental laws of physics are such as to permit many galaxies, many stars, and many planets to exist. Around 300K, very complicated chemistry is possible. Why is the periodic table so rich? Why is carbon so gregarious? Why is liquid water so friendly to complex chemistry?

Don't take what I write on faith, or as the definitive word on anything. Read Paul Davies or Martin Rees.

I believe that that would be called random chance, guys.

I have written here

about the mysteries of the fine structure constant, which governs all chemistry and radiation. If that constant differed from its actual value (about 137.036) by more than about 1% either way, would biology and life still be possible? If yes, then the value of that constant can be determined by chance and not matter. If no, why are the fundamental laws of physics friendly to the emergence of intelligent life?? We honestly don't know.

Buckminster, who are you quoting, and who is the U of Alberta physicist referred to?

hey thanks :o) I used to know most of this. Lost it with brain damage. It's more difficult for me to visualize these things than it once was. It's the idea of the expansion of space that is most intriguing to me. it's not velocity of matter from the big bang or gravity, but the simple expansion of space in between matter. Static yet progressive. To me I see it as a 4 dimensional vaccum overlaid onto the universe. I will check out your list. I probably have a lot of what you have already in my library. I've just forgotten it all.

That the universe must expand over time, at a rate that may exceed the speed of light, is a fundamental implication of the accepted (Friedman-Lemaitre-Robertson-Walker) solution to Einstein's fundamental equation of general relativity (GE). Einstein himself did not appreciate this implication of his own work. And GE is emphatically 4 dimensional, as you suspect.<br />
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To learn more about attempts to go deeper than this, read about "dark energy." About 3/4 of the matter-energy content of the visible universe about us consists of dark energy that mainly manifests itself as expanding space.<br />
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Wikipedia is quite good on this topic. I have posted my bibliography for intelligent lay readers under "I Love Cosmology." Those are the books that educated me. I am not a trained natural scientist.

very good post ! What intrigues me is that the space between matter is expanding for no apparent reason. Do you have any theories on that ? In my mind, it would take a 4 dimensional force of some kind to be able to pull it off.