Wednesday, January 10, 2007

Evidence: What are we looking for again?

This article about the possibility that a NASA probe that landed on Mars in the 70's may have killed the life it found there illustrates precisely my next question: What "evidence" do we look for anyway?

Let's start with the article. A NASA probe to Mars may have killed Martian microbes. Why? Because the search methods used were meant for water-based life forms. Martian microbes may not be water-based.

In the 70's, we had a firm stance on what would constitute life and the environments in which it could exist. Scientists accepted as fact that life required water, sunlight, and a certain temperature range. In the last 30 years, organisms on earth known as "weird life" have expanded our understanding of life substantially, completely obliterating the "scientific facts" of the past. So, as we search for life in the universe, we're not quite sure what we're looking for or how we'll find it.

This problem (the "What the heck are we looking for again?" conundrum)plagues science in a variety of fields. We're not quite sure what evidence there would be for a variety of phenomena or how we would even begin to look for it.

Let's begin with an easy example to demonstrate how evidence might work in the real world. Let's say I want to know if there's an adult African elephant in my cubicle. How would I find out? Well, I know what characterists an adult African elephant must have in order to be an adult African elephant. It can be perceived directly with the senses. It's visible and has certain physical characteristics: four legs, trunk, tail, tusks, greyish skin, etc. It makes a particular noise and probably smells rather bad. So, all I have to do is look, listen, smell, and feel around for the elephant. Nope, no elephant.

If I were to discover some organism in my cubile that ISN'T an elephant, I can match its characteristics to a known species or to basic descriptions of similar species by answering basic questions. Animal or plant? Size? Color? Smell? Mobility? Taste? (I think I'll skip the tasting part.) I think you get the point.

Now, what about these:

Multiple dimensions? Multiple universes? What evidence would there be for dimensions or universes we can't observe directly? Both of these theories are currently (in my opinion) a kind of "science of the gaps" that allow us to answer difficult questions. (How do we reconcile what we've learning about the behavior of the supermassive with our knowledge of the supersmall? How is it that our universe happens to be so finely tuned to life?) But we don't have the foggiest idea of how we'd find the evidence or what evidence there would be. (String theorists have thus far focused on mathematical models, none of which has worked.)

Ghosts? What evidence would there be if a ghost were in my cubicle? If I happened upon a ghost, how would I be able to determine that it is, in fact, a ghost and not a hallucination? What characteristics would a ghost have anyway?

ESP? Many have set up experiments that would detect ESP that is under the control of the subject with no success yet. However, what if ESP isn't under the control of the subject. What if it's a strange sense that's only available to us while we're in a very particular unconscious state? (I think this is more likely, since we don't really have control of the senses we know we have.) What if it's an external phenomena (like quantum potentialities) that we can only perceive when we're dreaming? What if....? Well, how would we figure it out? How do we test for an uncontrollable sixth sense that is present only when we're in a very specific unconscious state? Could there ever be any more than anecdotal evidence from strange dreams that came true?

All of us believe in things that we can't quite point to evidence for and, to be honest, wouldn't know what evidence to look for in the first place. It's easy to say that we can't accept an idea under those conditions, but how much would we give up?

Most of us could live without belief in ESP and ghosts and maybe the world wouldn't be harmed by our ignorance on the matter. But what of the scientific questions? Is it better that we accept some ideas despite this problem for the benefit of science? Do we just hope that we stumble on the answers some day? At what point in our search do we surrender?

2 Comments:

Anonymous dan from ideasandhowtheyspread.com said...

Good Post.

Scientific ideas spread in ways not unlike pseudoscientific ones, and the difference is not always clear.

12:53 PM  
Blogger Melinda Barton said...

Thanks. It is, in fact, extraordinarily difficult at times to draw the lines between pseudoscience, protoscience, and science. Thus, perhaps, the controversies surrounding popular theories like memetics.

4:32 PM  

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