I Hate it When A Biologist Says...

"Physicists are stupid because their experiments exist only to prove their theories and if the experiments disagree with the theories, physicists say that there's something wrong with the experiment instead of examining the theory..."

[Disclaimer: Okay, so any biologist who says something like that isn’t much of a biologist. Clearly, he/she doesn't understand how science works. So, this is not meant to be a rant about biologists. However, I have heard something like this said not once, but twice; and both times, it came from someone who was involved in biological sciences….Carolyn Day and Jared, be sure to read carefully…]

I will say, quite boldly, that this is one of the dumbest things I have ever heard for the reasons listed below. Taking a deep breath, I begin...

1. I don't know what they do in the Biological Sciences, but I will say this about Physics: It is NEVER true that an experiment exists to prove a theory. Nor does it exist to disprove a theory. Physics, like any other science, is an experimental science, and that's not what experimental science is about. Experiments exist to investigate phenomena. Now, do experiments investigate phenomena that are connected to someone's theory? Yes, very often they do. Here's why: Physicists actually want to understand the physical universe (and I mean REALLY understand). In order to truly do this, Physics requires BOTH theory and experiment (okay, so that was as much a lecture for physicists as it was for anyone else...;) ). Theory gives you the understanding of the physical laws of the universe. Experiment gives you the facts. In order for a field to be considered a science, you cannot have one without the other (notice, Miss Day, that the social sciences are starting to rely more and more on the techniques provided by the natural sciences...and by that, I don't necessarily mean Biology) and still call what you are doing science. This is the legacy that was passed down to us by Galileo Galilei and others of that generation. Science went from being philosophy and theology to being more like the science we know and love today. [This is also the reason why string theory is often criticized for not being science but math or philosophy: because right now, string theory cannot be experimentally tested.] Does that mean that all we care about is experiment (as is often implied by philosophers and mathematicians)? No! Without theory, you have no idea what the data mean! We need BOTH!

2. This is the nature of science. I want to understand something. I get an idea about this something. I design an experiment to test this idea. I (or someone else…as I can’t get my hands dirty with data…;) ) run the experiment. I get results. I determine whether the results are reliable (and yes, this matters). If the results aren't reliable, I run another experiment (NOT uphold my hypothesis as it is so wrongly assumed). If the results are reliable, I determine whether they agree or disagree with my hypothesis. If they agree, my hypothesis becomes a theory (and no, hypothesis is not the same as theory) and what are we arguing about? If they don't, then what's wrong with the hypothesis (NOT what's wrong with the experiment as it is also wrongly assumed)? This is the crux of what we call the scientific method. This is how it is done in Physics, like every other science. I have worked in both experiment and theory, and I know that when experiment and theory disagree, there's only one time when someone says there must be something wrong with the experiment: when there's something wrong with the experiment. What these two pseudo-biologists (neither were really biologists) wrongly criticize are circumstances in which there really is something wrong with the data or the data aren't enough to rule out a theory (and no, I don't mean hypothesis...theories have some experimental basis already; if you have to throw out a theory, you either have to go back and reinterpret the old data, or determine if there was something wrong with the old data). Both situations happen in any science field. Sometimes data is corrupted because of mistakes. This is sad, but corrupt data doesn't tell anyone anything. [Surely, you guys aren't suggesting that we should base our understanding on unreliable data, are you?] And sometimes, our experiments just aren't good enough to rule out a theory. Data plagued by huge error bars aren't going to tell you much, either. Sure, they can rule out theories with outrageous predictions, but they can't rule out ones that make more reasonable predictions. In this case, no one, and I mean NO ONE, ever says that there's something wrong with the data. They always say that the data are not inconsistent with some theory. This actually makes experimenters happy. Why? Because they have even more of an excuse to do another experiment. The only situation that I can think of in which theorists weren't ready to throw away a theory in the face of seemingly inconsistent data was that of the famous Solar Neutrino Problem. The idea is that the Sun is powered by nuclear fusion. The nuclear fusion processes give off the light and heat that we enjoy from the Sun. However, if we believe Nuclear and Particle Physics, then we know that these nuclear processes also emit neutrinos. Experiments were designed to detect neutrinos produced by in the Sun through nuclear fusion. One experiment found that there were many fewer neutrinos than expected. At first, no one believed this experiment. Why? Because other experiments didn't see the same result. Later, more experiments came out and also found a dearth of neutrinos. However, astrophysicists weren't ready to throw away the theory. Why? Because we had gone down the list of possible explanations for how stars do what they do. The only thing that we could think of that worked was nuclear fusion. If it turned out that our theory was wrong, we'd have to throw out all of stellar astrophysics! Okay, so I know what you're saying: "So, you'd have to go back to the drawing board. Isn't that what you're supposed to do?" Yes, that is if you really understand what the data are saying. See, astrophysical experiments were consistent with stellar theory. So, whose experiments should you believe? Also, which part of the theory is wrong? The nuclear furnace interpretation? The nuclear fusion processes? Nuclear Physics? Particle Physics? So, no. We weren't ready to give up on a theory that explained astronomical observations of stars because of data that we didn't understand. That was our argument. Are we sure we truly understand the data? Now, before you dismiss that as a cop-out, know that it's a fair argument. After all, how often do you miscommunicate a message because of lack of understanding of what someone else said? Ever play Telephone? This was the Solar Neutrino Problem. Particle physicists insisted that the astrophysicists were wrong, and astrophysicists insisted that the particle physicists were wrong. Who was right? The astrophysicists. The answer was that we really didn't understand what the solar neutrino data was telling us. It wasn't that stars aren't powered by nuclear fusion. It's that the neutrinos we expected to see (electron type neutrinos) were changing flavors to types that the experiments couldn't see. Later experiments verified this, and that was the resolution of the Solar Neutrino Problem. There was nothing wrong with the experiments, and no one said that there was, but there was nothing wrong with the theory that was supposedly inconsistent with the data, either. We just didn't understand what the data actually meant.

3. How often is someone going to throw money at you for running an experiment for no real reason? Never. When someone proposes an experiment, very often, it is for the sake of testing theory. There's a good reason for that. How do you know that an experiment is going to give you something useful, otherwise? Without theory, you could very well end up wasting a lot of time and money. So, when scientists (experimenters AND theorists) propose an experiment, theory is nearly always the motivation. Does this mean that experiments are the slaves of theory? No. In Physics, we go through periods in which experiment is ahead of theory and vice versa. A perfect example of a period in which experiment is ahead of theory is the present period in cosmology. Right now, cosmology tells us that we understand only 4% of the universe. 'Nuff said. What tells us this? Certainly not theory. It was experiment that told us that we have dark matter and dark energy. And it's experiment that's probing the questions provided by both now. We do have theories for dark matter and dark energy, but if you back a cosmologist into a corner (well, actually, you don't have to, they use this fact to drum up excitement), they'll admit that there really aren't any good ideas. Why? Because we don't really know anything about the properties of dark matter and dark energy. Sure, we know that dark matter interacts gravitationally (that's how we found it in the first place), but that's all we know. Dark energy? We know even less about that. Need I say more? Besides, it's not always the case that experiments are motivated by any particular theory. Take the Sloan Digital Sky Survey. It's main motivation is to map out a large portion of the sky. This is very important for theory, especially cosmology, but there's no particular theory that's being tested. These types of survey studies are not only common in astrophysics, but also essential for the study and understanding of astrophysical phenomena. Experiments the slaves of theory? I don’t think so.