These days, criticizing or questioning statements on science can get you called an idiot or even a heretic; science has become a matter of religious faith for some. If a scientist said it, they believe it, and that's that. Yet the very nature about science is not to be an authoritative voice, but a method of inquiry; science is about asking questions and wondering if something is valid and factual, not a system of producing absolute statements of unquestioned truth.
It is true that people need that source of truth and it is true that we're all inescapably religious creatures, so that will find an outlet somewhere. Science just isn't the proper outlet for it.
I took an online quiz about scientific issues sponsored by Smithsonian Institute recently, and I did well on it: 12 out of 13 because I forgot Nitrogen was the primary atmospheric gas. But one of the questions presumed that plate tectonics is absolute unquestioned fact.
If you don't know what plate tectonics is, briefly it is the theory that the earth's surface is made up of gigantic plates suspended on molten rock that slide over and under each other. The theory states that these plates were once in such a pattern that all of the planet's major surface continents were melded together in a proto-continent called Pangea (pictured above), and the rest of the planet was covered with water.
This theory is well-supported with physical evidence, such as similar rock found separated by oceans between South America and Africa, ridges of apparently extruded rock in the oceans, and multiple faults where one plate appears to be sliding under another, often causing earthquakes (such as the San Andrea fault). While these plates move at millimeters a year at most, they are believed to be in continuous motion.
At present, there's no reason to doubt this is what is taking place. It certainly seems plausible and likely given the best evidence we have right now. But I stop short of calling it fact for a reason that many recent scientific theories cannot be.
The problem is that there's no way to test or confirm this theory. You can make a model and see it work, you can check out types of rock and examine fault lines, and you can make measurements, but that's only going to tell you small portions of information in very limited time frames. Because the earth is so huge, and because there are so very many different pressures and influences on everything on a planet, you can't be sure without observation over time.
And since the theory posits that it would take millions of years to really demonstrate this to be true, humanity cannot test it enough to be certain. So all we're left with is a scientific theory: a functional method of interpreting data. In other words, it cannot be properly or accurately describe as fact.
This is true about other areas. The word "fact" is thrown around so casually with science and is defended angrily by people who really ought to know better. Cosmology does this a lot. Its a fact that the universe is expanding from an unknown central explosive point (although there is a fair amount of data that's throwing this into question). We can't know because we can't have enough data and there hasn't been long enough to really test this.
Michael Crichton's criticism of global warming was along these lines. He didn't deny anything, he just said its too big and complex a system that we understand far too little about to even attempt to make any absolute or authoritative statements about it. Science has gotten us far beyond our ability to properly measure or interpret the data at hand, but some still keep trying to make absolute statements anyway.
The theory of evolution is the same kind of thing. Many will state with absolute certainty that this is fact, but again, its something we cannot prove.
All the fruit fly experiments and bacteria being forced to adapt to chemicals and such in the world do not at any point demonstrate species evolution. They can't; even the fastest developing generations in the world cannot develop fast enough to show the million or more generations required to show a change in species. Its the same problem as plate tectonics: we can't see it happen, cannot test it, cannot verify it. The only thing anyone can do is speculate based on bits of information and speculation.
And that's the heart of a scientific theory. It isn't like a geometric theorem (a statement or formula that can be deduced from the axioms of a formal system by means of its rules of inference), or a theory that Sherlock Holmes might develop ( a proposed explanation whose status is still conjectural). A scientific theory is a system of interpreting data (a coherent group of general propositions used as principles of explanation for a class of phenomena). Its a step beyond a hypothesis, which is simply speculation or a guess, but is not proven fact.
Confusing theory with fact is really not excusable for an educated person, but some theories are so wedded to worldviews and hopes that they become a matter of argument and even rage. Questioning that theory means you're an idiot, uneducated, worthless. If you doubt this theory, you're clearly someone who is wrong about everything and should be totally ignored in life, even showered with contempt.
And when you're that closely wedded to a theory, you can become defensive, and try to argue from overwhelming force, using absolute terms to crush your opponent to avoid any possibility of discussion and debate. It shows tremendous weakness in your position to do this, but we rarely are aware of how true that is until long after the debate, if ever.
And a site that's sponsored by the Smithsonian Institute really ought to know better. No good scientist should ever claim a theory of this sort is fact. If they do, its time to question their motives and adherence to proper scientific method.