As I pointed out in my last post, it seems to me that the very existence of the Universe demands an explanation that Science cannot provide. Natural science is fundamentally a description of the way the universe is and doesn't really address why it is one way and not another. A scientific explanation is at its heart a description of phenomena in terms of a more fundamental phenomenon. We say the apple falls because of gravity, which is an attraction between bodies that have mass, which might be further described in the way they affect space and time around them, or in terms of special particles or fields. Science can also tell us the many consequences, both obvious and subtle, were gravity to not exist, but ultimately, at the most fundamental level, it cannot tell us why our universe is constructed in a way that includes that which gives rise to gravity as opposed to one that doesn't. This is not because the science is incomplete, but because those questions belong to the realm of metaphysics, where we need philosophy or perhaps theology to answer them.
In addition to the curious fact that there is something rather than nothing, there is another curious fact that many things in our universe and world are just right for life. Just like Goldilocks found only one of several possible bowls of porridge to be just right, there are numerous fundamental entities and forces that are just right for a universe in which life could exist. Prime examples include the relative properties of different fundamental particles and the strengths of different fundamental forces which, if even slightly different, would result in a radically different and inhospitable universe.
One example involves protons and neutrons, the two particles of which the nucleus of all atoms are composed. While the known subatomic particles exhibit a large range of masses, somewhat unusually neutrons are almost exactly the same mass as protons, only about 0.1% heavier. This leads to the fact that an isolated neutron will eventually decay into a proton (though taking a much longer period than most subatomic particles) but neutrons are stable inside bonds that hold a nucleus together. If they were lighter than protons, protons would turn into neutrons, and no atoms would exist in the universe. If they were an additional 0.1%-0.2% percent heavier, they wouldn't be stable inside an atom and we would have a universe of only hydrogen. Even if just a little bit lighter-say only 0.05% heavier than protons-would give us a universe of massive thermonuclear bombs instead of stable stars. At that mass, neutrons could not decay into protons, since they also produce an electron in the process, and there would be roughly as many neutrons as protons in our universe. Besides size, the biggest difference between a hydrogen bomb and our sun is that the former contains lots of hydrogen that contains neutrons, which allows the nuclear reactions to happen very quickly, while the stars mostly consist of hydrogen that does not contain any neutrons. Thus if neutrons were just a tiny bit lighter, our sun and the rest of the stars would burn out quickly and be unstable in the process. In summary, of all the different masses a neutron could have, it lies within a very narrow range that makes it possible for ourselves and everything we know to exist.
Another example of the perfect balance of the universe is the strengths of the fundamental nuclear forces. These two are known as the strong and weak nuclear forces because by one way of measuring the strong one is about 1040 (ten thousand trillion trillion trillion) times stronger than the weak. Were the strong nuclear force only a few percent weaker, there would be no nuclear reactions in stars producing other elements because deuterium (a proton and neutron together which is the first step in the process) would not be stable. If it were a few percent stronger, regular hydrogen would become as explosive as that found in hydrogen bombs, as the strong force could bind two protons together without any neutrons. This is because the critical first step in nuclear fusion requires that the two forces work together to form deuterium out of two protons, which is really hard and therefore really slow due how weak the second force is. If it could be bypassed, or it were stronger, such 1/1039 the strength of the strong force, nuclear fusion would happen much faster, rendering most stars unstable. If on the other hand, it were even weaker, like 1/1041 the strength of the strong force, there would be little energy from the sun and few elements besides hydrogen.
These are but a few examples of situations were properties of fundamental particles and/or forces happen to lie in a narrow range that makes possible the universe that we know. There are others that involve gravity and the electrical force, the density of mater in the universe, the mass of neutrinos, and others. They are all situations where something is neither too strong nor too weak, neither too heavy nor too light, but are just right. These are also things for which we have no working theory as to why they have the strength or mass they do; it is conceivable that they could have had very different values, but we are fortunate that they have the specific values to allow the universe that we know to exist.
In my next few posts I will discuss more about some of the amazing balance that we find in the structure of the universe. These of course seem to me to be fingerprints that point to something more than material reality, but don't take my word for it yet.
Image: Test of hydrogen bomb "Mike".
No comments:
Post a Comment