There is a catch-22 to the ‘falsifiable rule’; a large hubris-filled quagmire that has trapped so many in the past, and to which our current crop of cosmologists have fallen prey. Falsifiability is the acid test for the conceptual health of a scientific theory, but doesn’t really apply to a scientific fact. The flat Earth concept is an (unfortunately too appropriate) example of this. The idea that the Earth is approximately spherical (or at least far more spherical than it is planar) is not a theory. It is a fact, and one of the ways to recognize the difference between the two terms is to try to imagine a test for which the ‘mostly spherical Earth’ concept would fail. We could say, for instance, that the Earth is really flat with a center at some special location (say New York), but that when we travel away from it, say from New York to New Zealand, we are actually beneath its ‘real’ surface, and for some unknown reason on this part of the globe its structure is transparent and very low density. Since this explanation is (on its best day) utterly ludicrous, along with any other ‘explanations’ for why the Earth is actually flat, we correctly deduce that the Earth is to a large extent spherical, and we are held to its surface by the same force that gives it this shape, the magical force of gravity.
I’m sometimes asked if I believe in the theory of evolution. To this I respond that evolution is a theory in the same way that our basic composition of atoms is a theory. You can’t look right at it and see it happen (like seeing our beautiful mostly spherical Earth from space), but you can actually see evolution happen rapidly on a small scale with viruses and bacteria, just like an atomic force microscope will give you a glimpse of atoms. So in the same way as the term fact is often misused for nefarious purposes, so too is theory used as a label to denegrate perfectly respectable facts.
Which bring us back to the Big Bang. The most arrogant answer to our question of its falsifiability is that it is a scientific fact, and as such should not be falsifiable, any more than the mostly spherical Earth fact. Well, ahem, pardon me for asking… Since there are no strict rules for when a theory becomes a fact, there is no quick retort for this defense, other then perhaps, the time-honored ‘IS NOT!’. And unfortunately, Big Bang proponents have upped the ante by segragating (think of the many headed Hydra here) portions of the Big Bang into distinct buckets of fact and theory. Under fact we have things like the expansion of the universe and the idea that it ‘did happen!’. Under theory we have wrangling about various details, such as early galaxy and star formation. So let’s just look in the Big Bang fact bucket, and see if there’s really anything in it, at least on par with much venerated scientific facts; facts that are so solid that you could trip over them whilst descending the stairs, for instance.
After a careful inspection, we note that the Big Bang fact bucket is pristinely empty, because every single piece of evidence that exists for the Big Bang is, by definition, indirect. We can measure the CMB directly, but have to presume that it is relic radiation. We can measure the intergalactic redshift, but not in the lab. We can praise the few predictions the Big Bang has made, as long as we ignore the many more that it has failed (shouldn’t the universe, full of all of this matter, be decelerating right about now??). The only reason the Big Bang is considered a fact at all (or at least its basic premise) is because there is a general concensus as to the weight of a great many retrospective and circumstantial bits of evidence. This is a murder trial without a body, a murder weapon, and whose witnesses were at a great distance looking into a dark alley. So just as absence of evidence does not constitute evidence of absence, a large pile of weak evidence does not constitute strong evidence, and evidence does not become stronger by winning a popularity contest.
So for those who have been able to convince themselves that the Big Bang is fact, by peer pressure or justing wanting it to be so, I say two things. First, you have done a horrible disservice to the status of scientific fact, and two, I’ve got some prime Florida swampland for sale…
