You exist. You are a biological life form. Therefore, the Universe must be the sort of place that has the sorts of physics that permits the origin and evolution of life forms. That that weren’t the case, you wouldn’t exist. Now the question is, why is this - our bio-friendly Universe – so?
The fact that you exist makes some people quite uncomfortable. Specifically, the fact that the Universe – translated, the laws, constants and relationships of physics – is bio-friendly and allows for the origin, development, evolution, and overall the existence of living things makes some cosmologists and physicists uncomfortable. Current explanations of why the Universe should be bio-friendly don’t sit well with some subsets of this professional community.
Well, we’re here, and so are they, and so are millions of other species (past as well as present), so they just gotta deal with the situation as it presents itself.
Before we get to the ways and means they deal with as explanations for the bio-friendly situation, and why those ways and means can be uncomfortable, I need to point out that all these same laws, constants and relationships of physics also can be very bio-unfriendly – in spades; in the extreme.
Take the entire volume of our observable universe (we don’t know what the volume is of the Universe as a whole). What fraction of that volume is bio-friendly to you? If you were somehow transported at random, by chance, to some other coordinates somewhere in that expanse of space, what are the odds you’d live to tell the tale? Bugger all! Winning a million dollar lottery a million times in a row I’d be happy to give you better odds on. In the vacuum of space, nobody can hear you die; if you happen to hit a star, nobody will see you fry.
Even Planet Earth is largely bio-unfriendly. Ten kilometres straight up, you’re dead; ditto ten kilometres straight down. You’re odds don’t improve greatly if you’re in your birthday suit and land in Antarctica, or the Sahara Desert, and how long can you tread water if dumped in the middle of the North Atlantic?
So, 99.999 (add a few more nines and then some) percent of our observable universe is NOT bio-friendly. The only place you know for sure of surviving, and even then maybe not for very long, is just on the very thin surface of the third rock outwards from Mother Sun.
Now that’s a rather bio-unfriendly observable universe to you, and other terrestrial complex life forms like cats and dogs – even cockroaches. It’s not quite as bio-unfriendly to simpler life forms, although the odds don’t improve all that much. Some microbes might survive inside outer space, but they’re not going to thrive, far less reproduce, and otherwise live the good microbial life. Now some non-terrestrial abodes in our solar system (and presumably other extra-solar systems) might be suitable habitats to our microbial ancestral kin, so from their point of view, the observable universe is a slightly more bio-friendly place – but suitable bio-friendly real estate is still pretty marginal relative to the overall volume of same.
Anyway, the bottom line is that the Universe is ultimately a bio-friendly place. How is this possible? And what are the uncomfortable aspects of explaining this?
Firstly, we assume that there was an alternative. Our Universe could have turned out to be an absolutely bio-unfriendly place. For sake of visualization, imagine that all those laws, constants and relationships part and parcel of physics are all represented by dials on this machine that ultimately runs or controls the Universe. Let’s say that all the dials that control the Universe (and its bio-friendliness) are all set at position #5. All dials at setting #5 make for a bio-friendly Universe.
We can perform imaginary thought experiments, a ‘what if’ game, by altering the position or setting of any one of those dials. Say one dial represents gravity. If we turn the gravity dial to #4, the force of gravity is weaker. If we turn the gravity dial to setting #6, gravity is stronger.
It turns out, nastily so, that changing the positions of even any one of the dials by even a small amount makes our Universe 100% bio-unfriendly. The position of the dials is fine-tuned to an incredible degree of precision to allow for a bio-friendly Universe; to allow for you and for me and for cats and dogs and cockroaches too.
Take the gravity dial. If gravity were ever so slightly weaker, stuff wouldn’t clump together; interstellar gas wouldn’t coalesce into stars, and if stars wouldn’t form, then no life. Life needs stars, because ultimately stars cook the heavier elements out of which life is made – like carbon and oxygen and nitrogen.
If gravity had been a shade greater, then the newly Big Bang expanding universe would have been aborted quick-smart as expansion would have turned into a contraction in fairly short order resulting in a Big Crunch. There would never have been time for life to even get started before Armageddon!
So, how did all the dials get stuck on the #5 position?
Well, maybe it all just happened by a random throw of the dice – all by chance. Some combination had to come up and bio-friendliness was one whose number came up. That makes some professionals queasy or uncomfortable in the same way as explaining someone winning a million dollar jackpot a million times in a row would. The odds are just too great against the possibility.
Well, maybe our bio-friendly Universe was the outcome of an intelligent designer. It was deliberately created to be bio-friendly, just like we humans can design a car to be driver-friendly. Lots of gadgets are advertised as being user-friendly. Why not therefore an entire Universe? Of course the agent(s), the designer(s), would have to have been outside our space-time continuum since presumably he / she / it / they existed before the creation of our space-time continuum. I guess that means that creator person(s) or thing(s) must have been supernatural in origin – God, in other words. Now the God concept or hypothesis, or intelligent designer theory also puts some professionals’ teeth on edge. Lots of folk reject that idea; lots of folk embrace that idea too.
Lastly, what if there are lots of universes – I means lots and lots and lots of them. Nearly all of them would have few, if any, dials set at #5. Maybe several have nearly all dials at #5 – close, but close don’t count. However, based on sheer probability, a couple, maybe just one, maybe two or three – a select few, won the all #5 dial lottery. Alas, multiple universes, the Multiverse concept, doesn’t sit well with all and sundry either. If you have lots of universes, maybe you have an infinite number, which then implies an infinite number of copies of everything – of you, of me, of every cat and dog – and every cockroach too.
But what if there’s no Multiverse in space, only a Multiverse in time. That is, a cyclic universe. Sooner or later, one cycle is going to produce #5, #5, #5, #5, #5, #5, etc. right on down the chain. Is ours, are we, that lucky cyclic Universe? Therein lies the rub. Our Universe doesn’t appear, based on current observational evidence, to be heading in a cyclic direction – towards a Big Crunch - now, or ever. So, if we are the last production of a previously endless cyclic process or chain, then we broke it!
So, all ideas explaining a, and in particular our, bio-friendly Universe have their plusses and minuses.
But wait, there’s more! What if our ‘what if’ game isn’t possible? Maybe there’s one, and only one physics possible. Maybe all the dials are super-glued at position #5 and just can’t be moved. I believe it was Einstein who asked whether God had any choice in creating our Universe’s parameters. Maybe not, in which case maybe God isn’t as all powerful as he / she / it / they is/are cracked up to be – but that’s another topic. If all dials are set on position #5, therefore any other laws, constants and relationships of physics are purely in the realm of abstract or hypothetical thought-experiments
There is however one other scenario, actually scenarios, that have a bearing on the issue. The laws and constants of physics have interrelationships, and thus, it might not be possible to alter one dial without affecting the position of other dials. The prime argument is that altering the position of any one dial makes the Universe bio-unfriendly. However, I wonder whether altering more than one dial might restore a bio-friendly Universe. Translated, we probably move into the life-not-as-we-know-it area, which traditionally has played around with replacing silicone for carbon; liquid methane or liquid ammonia for liquid water. But altering more than one dial has near limitless possibilities way above and beyond traditional life-not-as-we-know-it scenarios. Maybe changing dial one from #5 to number #4 makes a universe bio-unfriendly, but if dial seven is then changed to position #9 and dial number three is altered to position #2, then maybe a non-carbon based life-form might be possible. The possibilities, again, are near endless, although in general nearly all combinations of dials produce lifeless universes, maybe, just maybe, some combination, other that all #5’s, might also do the bio-friendly trick. I don’t know, but can it be ruled out of the question based on current understandings?
So why is the Universe bio-friendly? I’m not sure, but I strongly suspect that the ultimate key concept here is that of a Multiverse. But be it design or random probability, is it any different than asking why the Universe is chemistry-friendly, or for that matter even physics-friendly? Accept the fact that our Universe just is, uncomfortable as that might be to some, because if it weren’t, I wouldn’t be here writing this and you wouldn’t be there reading it!
*With apologies to the late Alfred Hitchcock for twisting around his “Dial M for Murder” phrase.
Further readings:
Barrow, John D.; The Constants of Nature: From Alpha to Omega; Vintage Books, London
Barrow, John D. & Tipler, Frank J.; The Anthropic Cosmological Principle; Oxford University Press, Oxford
Davies, Paul; The Goldilocks Enigma: Why Is the Universe Just Right for Life?; Allen Lane , London ; 2006:
Morris, Simon Conway; Life’s Solution: Inevitable Humans In A Lonely Universe; Cambridge University Press, Cambridge
Rees, Martin; Just Six Numbers: The Deep Forces that Shape the Universe; Phoenix , London
Susskind, Leonard; The Cosmic Landscape: String Theory and the Illusion of Intelligent Design; Back Bay Books, New York
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