“Science is facts; just as houses are made of stone, so is science made of facts. But a pile of stones is not a house, and a collection of facts is not necessarily science.” -Jules Henri Poincaré
The higher you fall from, the faster you’ll be moving when you hit the ground.
Seems like the most obvious thing in the world. You know this intuitively, of course, based on all your experience in the world. Drop an egg from too great a height and it breaks.
While you wouldn’t be afraid to jump off of a diving board like the one above, jumping from a greater height might give you cause to worry.
Because even though you’ve never done it, you presume that if you jump from too great a height, you may break when you reach the end of your jump.
So how do you know whether it’s safe or not? How do you know whether you’re too high to safely jump?
Believe it or not, this is what makes science, and what makes scientists out of us.
We’re all taught some grand myth about the scientific method, like there’s one fixed way to do science.
Stripping away all the pretensions, all that science really is is the way we make sense of this world.
If this thing happens, what’s going to happen next? Well, you don’t just sit around and talk about it, pontificating on what you think, you go out and investigate it. You make observations and measurements about the different things that happen when you test it out under different conditions.
Perhaps you eventually learn that there are, in fact, some heights that you simply cannot safely jump from, and even, quantitatively what those heights are. And when you’re satisfied with what you’ve found, you can synthesize all your findings together, and say something that sounds profoundly intelligent and informed, like:
The higher you fall from, the faster you’ll be moving when you hit the ground.
And this grand statement, that pulls all your investigations, observations, measurements and experience together, describes not only the experiences you’ve already recorded, but extrapolates to a more general case, and allows you to make predictions about what’s going to happen for things you have not yet experienced.
And when you’ve reached this point, you have the beginnings of what can finally be called a scientific theory. You can start to predict, if you set up a system in a certain way, what it’s going to do next! If it does what your theory says, that’s evidence confirming your theory. But every theory has its limits, or a point where it breaks down.
For this particular example, the theory breaks down when an object hits terminal velocity, when the drag force (from air resistance, in this case) cancels out the gravitational force that accelerated you downwards. At this point, it doesn’t matter how much higher you fall from, you won’t go any faster.
But, of course, science has done better. Rather than a qualitative statement like the one above, we can determine, based on an accurate description of all the forces involved (including gravity, air resistance, wind speed, etc.), exactly how fast and in what direction — at any given time — a falling object is moving. Quantitatively.
And each time we test this theory under novel conditions or circumstances, we either get a great confirmation that our best theory is good in a new way, or we find that there’s more to the story than our theory can account for.
And for most of human history, science has progressed incredibly slowly.
Magnetism was first discovered in the 1200s (by Pierre de Maricourt), but it wasn’t until the 1800s that its connection with electricity and electric charge was understood, and it wasn’t until very recently that the quantum mechanics underlying magnetism were successfully described.
None of the subsequent discoveries made the earlier theories wrong, they simply discovered the limitations of those earlier ideas, and went beyond them.
It isn’t like biology started with the discovery of the fundamental source of our genetic code. Before the structure and function of DNA was known, scientists still knew plenty about genetics and inherited traits. If we bred certain living things together with certain traits, we were long able to predict what sorts of traits the population of offspring would have.
And before genetics — the mechanism by which living things inherit traits — we were still able to determine that the traits of living creatures changed over time, including the major mechanism by which it happens.
And even before Darwinian evolution took hold as the leading scientific theory, animal husbandry had been practiced by humans — breeding animals and selecting for certain desirable traits — for over 10,000 years!
Of course, science knows too much these days for any one person to truly be an expert in all of the details in all fields. That’s why we have scientific experts, who do know the relevant details in their fields. If there’s an alternative theory to evolution, it needs to not only explain the phenomena currently explained by evolution, it needs to accomodate genetics, DNA, and everything else that’s been built upon evolution.
The same goes for the Universe.
At one point in the past, the Big Bang was not even the leading theory of the beginning stages of our Universe. But as observations came in — of the cosmic microwave background, of galaxy evolution, of the initial abundances of the elements — the alternatives fell by the wayside, unable to keep up. Today, the Big Bang model predicts all sorts of phenomena — gravitational lensing, large-scale cosmic structure, fluctuations in the microwave background, etc. — found to solidly align with observables in a robust way that no alternative does.
Getting a scientific consensus on any issue is incredibly difficult, because the evidence needs to be stunningly overwhelming. If there are multiple reasonable explanations that fit the data even marginally well, you won’t get it.
We’re skeptical. We don’t believe explanations because they sound plausible. We observe. We calculate. We predict. We prod our theories and twist them in novel ways; we probe to the edge of their range of validity and beyond. We demand replications of experiments, and quantitative accuracy for a theory’s predictions.
But if all of the alternatives are grossly inferior — like they are for evolution and the Big Bang — you’ll find that over 95% of scientific experts in that particular field will, in fact, agree. And when those facts pose a danger to public health and safety, it’s more important than ever.
Because you may not die if you disbelieve the Big Bang; you’ll simply be wrong, and miss out on a deep and profound understanding of your origins and existence. (Which you are free to do as you choose, of course.) But if you decide to taste-test mercury or lead, or smoke a carton of cigarettes a day, or breathe heavily polluted air or ingest microscopic quantities of polonium, the consequences are much more dire. And so it goes with the Earth as well.
The case for global warming and global climate change has — among those scientists who study it — reached that level of consensus. I’ve encountered a great deal of skepticism over email and on this blog, and although I’ve been more than happy to write about the details I understand well, I myself am not a climate scientist, so I don’t get to be part of the experts who weigh in on its validity. I have to trust the experts, and the consensus they do reach.
And basically, there are four simple components of the consensus:
- The Earth is getting warmer, and the warming is accelerating.
- This warming is primarily due to human emission of greenhouse gases.
- If the emission of greenhouse gases continues unabated, this will continue to force the Earth’s average temperature to rise. As a consequence, the icecaps will melt, the sea level will rise, and the climate across many regions of the world will change dramatically.
- And finally, these happenings — and the ensuing natural disasters that arise from them (flooding, drought, etc.) — are bad things that we can and should do something about in order to avoid them.
The consensus is incredibly solid on the first three of these points is extremely solid (at the above 95% level I brought up earlier), and although I haven’t heard anyone (notable) contest the fourth point, it is possible that there are those who contend otherwise.
The second and third points are very difficult to contest scientifically as well, because humans have measurably emitted more than a trillion of tonnes of greenhouse gases, which demonstrably cause an increase in temperature in the same fashion that wrapping yourself in blankets causes an increase in your temperature. The physics is so simple and straightforward that — short of the problem of quantitatively modeling the magnitude of the temperature increase associated with increases in greenhouse gases — there is no wiggle-room to dispute it and still be scientifically sound.
So those who call themselves climate change skeptics have instead focused on the first point: trying to refute that the Earth’s temperature is rising, and that it’s rising at an increasing rate. Recently, Richard Mueller, noted climate skeptic, led a project to measure and scrutinize all the previous measurements of global average temperature, and to test just how confident we should be in declarations from NOAA, NASA’s GISS, and other sources that the Earth’s global temperature has been rising. The results?
This merged database of temperature data contains 1.6 billion records, all of which are accessible at www.BerkeleyEarth.org. You can also access the full text of their four papers submitted for peer review, and check out their Summary results. As you can see, they confirm with great precision the results of the previous studies, showing a rise over the past 60 years of an average of 1 degree Celsius, with the rise accelerating over the past 30 years.
From the summary report itself, Mueller himself had this to say:
Our biggest surprise was that the new results agreed so closely with the warming values published previously by other teams in the U.S. and the U.K. This confirms that these studies were done carefully and that potential biases identified by climate change skeptics did not seriously affect their conclusions.
Many others have reported on this study, and you should check them out if you have a chance. (Keep an eye out for moving goalposts.) You can also see, in incredible video detail, just how the temperature has changed over time across all monitored regions the Earth.
Although there have been many times where scientists are later found to be mistaken, science is the best — and perhaps the only — legitimate way to make physical sense of the world and Universe around us. So do something about it; it’s your world, too!