Sound Off !
Reply to Jim Currie's reply to Sam Francis "How Did the Universe Begin, How Will It End, and How Do We Know?"
January 25, 2014
Category: Science and Technology > Physical Sciences
Jim Currie, replying to my article on the origin and fate of our universe, asked two interesting questions, addressed below.
Multiple Universes?
Jim asked whether — since random quantum fluctuations are ubiquitous and responsible for the birth of our universe — other universes might have been created by these quantum fluctuations. The short answer is yes.
This question is a very active area of research by theoretical physicists, partly because it relates to the search (so far unsuccessful) for a quantum theory of gravity, unifying the physics of the very small (quantum mechanics) with Einstein’s theory of gravity in four-dimensional space-time (the general theory of relativity). Without a quantum theory of gravity, the physics of the birth of our universe — and perhaps other universes — cannot be understood in detail, because during the first 10-43 seconds of our universe, it was so small and hot that gravity inevitably took on quantum form.
However, almost every current approach to developing a quantum theory of gravity suggests that our universe is not unique. These theories include string theory, the theory of cosmological inflation, and others. Depending on how these theories pan out, multiple universes not only could exist, but must exist.
By the way, we can never directly observe these other universes. As with Las Vegas, “what happens in a universe, stays in a universe.” A universe has no boundary. No radiation from another universe — no evidence of its existence — can reach ours. If true, is the study of other universes properly part of physics, which deals only with falsifiable hypotheses? Good question!
Safe Haven?
Jim’s second question arose from my comment that homo sapiens is probably fated for an asteroid-caused mass extinction (like the dinosaurs) within tens of millions of years or, escaping that, certainly fated to become extinct as our sun consumes its nuclear fuel and expands as a red giant, engulfing the earth in several billion years.
Jim asks whether we might avoid extinction by finding a safer place to live. The short answer is a qualified no.
No other planet in our solar system can support our species, so we already inhabit the only option in the neighborhood. And even if we could emigrate within the solar system, we’d still face the same dangers. It would be like moving next door. As an alternative, setting practicalities aside, we might consider emigrating to a neighboring solar system, more than 4 light-years away. But all planetary systems were created by the same physics, so they all have asteroid belts and suns which die sooner or later. Darn!
The most plausible way of extending the life expectancy of homo sapiens is not to emigrate to a safer place, but to make this place safer, by developing the technology to detect incoming asteroids and deflect them from collision paths. Few would say that this isn’t technologically feasible, at least in the far future. Do we have the motivation and resources to carry out such a project? Is it wise? Beats me.