Video: Defining the Purpose of Scientific Experiments

Which of the following statements most correctly describes the purpose of performing an experiment? [A] An experiment is performed to discover new phenomena. [B] An experiment is performed to generate observations about a known phenomenon. [C] An experiment is performed to test a prediction. [D] An experiment is performed to confirm a hypothesis.

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Video Transcript

Which of the following statements most correctly describes the purpose of performing an experiment? Now we’ve been given four statements here. So let’s go to them one by one and see which one is correct. Number one, an experiment is performed to discover new phenomena.

So let’s think through this one. Is the purpose of an experiment really to discover new phenomena? Well, sometimes when we conduct an experiment, we can discover new phenomena. Something unexpected happens if say, for example, the scientist conducting the experiment does something wrong, or if the experimental setup is not working properly, or just coincidentally something different happens to what we expect.

And this may turn out to be a new phenomenon. However, did the scientist actually set up the experiment and conduct it to discover this new phenomenon? Well, no. They might have gotten lucky and discovered something new, but that wasn’t the purpose of conducting the experiment. So this one is not the answer to our question.

Let’s move on to number two then. An experiment is performed to generate observations about a known phenomenon. Now this one seems a little bit more like the answer. What it’s suggesting is that we conduct an experiment in order to get to know a known phenomenon better. However, this statement is quite vague. It just says something about generating observations.

So yes, this is closer to the correct answer, but it’s still too vague late for our liking. So this is not the answer we’re looking for. Number three, an experiment is performed to test a prediction. Now this is more like it. This is very specific. We conduct an experiment to test a prediction. The whole idea is that we come up with a hypothesis, an idea about what might be happening, in order to describe a known phenomenon.

Then we use that hypothesis to come up with predictions that we can test with an experiment. And the whole point of this experiment is to test the predictions made by the hypothesis. And hence, an experiment is specifically designed to test these predictions. And we can see why this statement is better than number two, because number two, like we said earlier, was too vague. It just talked about generating observations which, you know, it’s not gonna for us.

We need to be very, very specific. We’re designing this experiment to test this prediction made by this hypothesis. This allows us to be more systematic with our science. We don’t just wanna be hand wavey and generate observations. We want to specifically test a prediction made by a hypothesis. This way we can be systematic, as we said, because we can test all of the predictions made by one hypothesis and then move on to the next hypothesis.

In essence, it’s better for the admin part of science, because then we can very thoroughly test hypothesis and their predictions. So number three looks like the correct answer to our question. But let’s just make sure that number four is indeed incorrect. Number four says that an experiment is performed to confirm a hypothesis. Now this statement is very, very wrong and very dangerous. Why is that?

Well we can never ever ever confirm a hypothesis, because this is how science works. We come up with hypothesis, and we test it with experiment. If the experimental result disagrees with the predictions made by the hypothesis, then immediately we know that the hypothesis cannot be correct. But if the experimental results do agree with the hypothesis, then all we can say is that we’ve got solid evidence for the hypothesis being along the right lines.

However, we cannot confirm the hypothesis because we may have just gotten lucky and got the right results. Or the hypothesis may have given a correct prediction for the wrong reasons. Also the experiment that we conduct should never be performed to confirm a hypothesis, because as we’ve already said we cannot confirm a hypothesis, but also this statement suggests that the scientists already believes the hypothesis to be true and they’re just looking for experimental results to confirm it.

This sounds very much like confirmation bias, which is when you assume something is true and then look for results to back you up. And that’s not how science works. We should always be open-minded. So number four is not our correct answer either. Now just to clarify this final point as to why number four is not correct, let’s look at an example.

Let’s say we’ve got this hill, and we’ve got a ball at the top of the hill or nearly at the top of the hill. Let’s say that we hypothesize that the ball teleports from where it is now to the bottom of the hill and we hypothesize that it takes 10 seconds to get there. So what we do is we conduct an experiment. We place the ball at the start position. And then we check where it is 10 seconds later. Well 10 seconds later, it does end up being where we expected it to be.

So our experimental results agree with what we predicted. But does that mean that our hypothesis is confirmed? Well, no. This would be ludicrous. Like we said earlier, we just got lucky. The hypothesis that the ball teleports from the top of the hill to the bottom of the hill gave us the right answer for the wrong reasons. In reality, it probably just rolled down the hill and it took 10 seconds to do that.

However, for us to discover that assuming we didn’t know that already, we would have to conduct further experiments. We’d have to check five seconds later where the ball was. And we’d realize that the ball was somewhere halfway down the hill five seconds after we released it. And then we’d realize that it probably doesn’t teleport. But then maybe it did teleport from here to here. So maybe we need to revise our hypothesis.

And so that’s the point. We can never confirm a hypothesis. The only thing we can do is to conduct multiple different experiments to test various predictions made by a hypothesis. And the more and more evidence that we gather that agrees with the predictions made by the hypothesis, the more and more likely it is that the hypothesis is along the right lines.

But we can never 100 percent confirm it. We can only get close. But anyway, getting back to our question, our final answer is that an experiment is performed to test a prediction.

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