Laws of Physics

I attended a public lecture at Queen's Univ. last year in which a professor (from Cambridge I think) gave a lecture entitled "The improbability of the formation of life" or something to that effect.

In it, he showed how precisely the forces are balanced, how if the distribution of matter/anitmatter came out different we would not have come to exist. He would close each argument saying, "if such_and_such had been different, then life would not have formed. TOO BAD" then at the conclusion of his presentation, he adds up all his "TOO BADs" and shows that the probabability of life forming is exceedingly small.

So basically he argues as follows:
If the universe had followed a SLIGHTLY different path in its development, we would not be here. But my question is the following: if it had to all happen again, how do we know the exact same path would not be followed? Maybe this is the way things must come out, as governed by the laws of physics.

It's a little like a game of PLINKO on the Price is Right. Knowing the exact momemtum of the chip when it strikes each peg, we could figure out the path its going to take. It's 'not really random' as another thread suggests.

So my question is:

If we could set up a model of the early universe, could we show that the laws of physics would develop exactly as they for us, out of physical necessity? Or would a different set of laws come about?

dvst8

Yes, this is really interesting.
If you take this to a smaller scale:
You have two worlds exactly the same (not 1 atom is different at any given time)
On these two worlds you have two identical buildings
These bulidings are blown up by two indentical dynmite sticks at exactly the same time.
So will the debris from both buildings land in exactly the same positions.
I think it would.
However I think the main one of the determining factors is time.
What would happen if 1 building was blown up a second after the other? One factor that the time difference could affected is the wind.

What if the events that led to the begining of life had begun 1 second earlier. What could time have changed? Was there time. Or is there only time because we are here to observe it.

This thread has already seems to involve at least three questions. One: Is the existence of life a one-time freaky accident, not likely to occur elsewhere in this universe (and not in other universes, if any)? Two: Are the laws of physics an accidental byproduct of initial conditions in our universe or are they inevitable? Three: Do the same initial conditions always lead to the same subsequent events? This second issue brings up another question: Can we predict the future history of the universe from a precise knowledge of the current positions, velocities, masses of all the particles in the universe? Prior to about the time of Newton, the universe was viewed as capricious, ungoverned by laws of physics. In the 19th century some very intelligent people said that in principle, you could predict the future history. Current thinking denies this possibility, even in principle.

The first question has appeared on other threads, and has no absolute answer. I like the following analysis (hinted at by something I read).

The history of our planet contains the only evidence we have for the existence of life in general and for intelligent life in particular. First imagine compressing the history of the Earth into 1000 days. This is easier than comparing billions, hundreds of millions, et cetera.

Earth forms and starts to cool 1000 days ago
First life appears 760 days ago
Dinosaurs appear 54 days ago
Dinosaurs disappear 14 days ago
First man-like ape shows up 15 hours ago
Beginnings of civilization 3 minutes ago.

I do not claim that the above are precise values, but they are fair approximations. I used 4.6 billions years as the start of Earth's history (I think this is a good number). The other values I used were straight out of my memory, and may not be reliable (I think they are reasonable numbers). Note that there is controversy over most of these numbers, so precision is not possible.

Note that life appeared almost as soon as it was possible for it to exist. For the first "100 days" or so conditions were too hostile for life to evolve. This suggests that life probably occurs whenever/wherever conditions are suitable. The above makes me optimistic about the existence of some kind of life elsewhere in the universe. I would expect life to exist in many places.

Note that dinosaurs existed for a long time and disappeared without evolving what we would call intelligence. Furthermore, it is believed (with fairly good evidence) that they were wiped out by a freak accident, not because they were an unsuccessful species. This suggests that the evolution of intelligent life is not necessary for a complex and successful life form.

Note how long it took for something vaguely man-like to appear. This suggests that intelligent life might be a fluke. It certainly suggests that it is much rarer than life in general.

In the absence of other evidence, I believe that the above suggests that intelligent life is rare. Considering the size & age of the universe, the above also suggest to me that we are unlikely to be contacted by or find evidence of intelligent life elsewhere in the universe.

yes.

in fact i think the lecture of which i spoke was actually entitled "the improbability of the formation of INTELLIGENT life in the universe"

dvst8

I think that if you look at the universe from this point of view, you have to look at the smallest component that everything is made of, and do we really know what the smallest component is? One atom of hydrogen is not the same in time and space as another atom of hydrogen considering this electron at this position at this time etc.

You'd need to have "initial conditions" exactly defined (which I assume is what you meant).

Someone may come along and say electrons aren't exact enough. Sub-Atomic or even beyond the Sub-Atomic (or is that only Sci-Fi?) may be required for complete exact specifications of the initial conditions of the universe.

When we can specify such precision, we could probably also develop a transporter (merely an executioner-cloner as I have mentioned in another thread).

Also, weather "forecasting" would be a trivial matter.

By the way, I'm agreeing that if you had complete specifications of the universe at some time of its existance in the past (and there was no "Intervention" by an entity "outside" of this universe), then everything would transpire the same with repeatability.