Science Requires Positive Evidence

Finding explanations to what we observe is the essence of what science is. At the simplest level is it looking at the world and making sense of why we see what we see.

The science comes when we seek explanations in a systematic way. We take what we have observed, find an explanation that fits what we have observed and then, and this is the hardest part, question our assumptions to see if we should change our explanation, or more likely, expand our explanation.

While I have written this as a simple processes, understanding this process requires applying the process of science to the process of science itself. In the end you end up with a greatly expanded understanding of how not just science works but also how we interact with the universe.

Explaining this is not something that can be done in a single blog post, or even a single book, but it is a lifetime of learning. What I can do is provide examples of how science is either properly or improperly applied. Here I will give one example of a misapplication of science.

A few years ago an asteroid, that we named ʻOumuamua, from outside our solar system passed through our solar system. This was the first asteroid to be positively identified as having an unbound orbit. It was something that got a lot of attention and there were a few ideas proposed, such as gasses venting from the inside, or even we had measured its shape and mass incorrectly because it was spinning rapidly, or any number of possibilities.

Two astronomers at Harvard proposed the idea that ʻOumuamua was actually a spacecraft from an alien race. Their argument rested on the fact that as ʻOumuamua began its journey out of the solar system its velocity was not changing as we would expect. Its velocity was consistently too high. This would mean that there was something giving ʻOumuamua a push on its way out.

There is nothing wrong with proposing that something is evidence for extra-terrestrial life, it is after all an open question in science. But their motivation for their conclusion was flawed. Their argument rested on the fact that our measurements of ʻOumuamua's motion did not fit with our other measurements of its properties. Put simply, there was a difference between what was measured and what was calculated for its speed.

The problem with the alien spaceship theory was that there was no positive evidence pointing towards that idea. There only existed uncertainty in how it's motion could be explained by our other measurements of ʻOumuamua.

In the measurements of ʻOumuamua there was some uncertainty of its dimensions, spin, composition, and mass. ʻOumuamua's motion was not outside the possibility that it was just an asteroid and nothing else, just unlikely. Thus its motion did not constitute positive evidence for ʻOumuamua being an alien spacecraft.

Something is positive evidence iff its presence, or our knowledge of it, can only be explained by the proposed theory. That is, if the explanations needed to accommodate the new observations break our current understanding and theories at a fundamental level.

In the case of ʻOumuamua the difference between the measurements and calculations did not fundamentally break our understanding of physics. It didn't even make it exceptionally difficult to find other explanations that did not require it to be an alien spacecraft. Hence it could not count as positive evidence for it being an alien spacecraft.

If, for example, ʻOumuamua had been emitting regular radio signals with a defined pattern, then that would be positive evidence. In our understanding of physics there is no way for a hunk of space rock to make radio signals with a regular pattern. But to have its motion be slightly off from what we calculated, that is not positive evidence. Therefore not only is the idea not supported by the evidence, but proposing the idea was not supported by the evidence.

The critical thing that separates new scientific ideas from normal speculation is that there must be positive evidence first. This is a minimum bar to separate science from non-science. Finding evidence of aliens is perfectly within the realm of science, but we must be careful because not all things can be positive evidence for aliens.