THE "OBSERVER EFFECT" tells us that it is impossible to observe something without changing it. Whether an animal's behavior or a speeding electron, characteristics of both are inevitably altered in our attempt to know them. Science is supposedly a pure discipline, untainted by bias or prejudice in its search for truth. Of course its practitioners know this for the utopic optimism that it is, but still the question must be asked: if the mere act of observation biases results, how can conclusions be drawn from them in good faith? Observation is the scientist's greatest tool. What does it mean then, if using it undermines the principles science is founded upon? Is it truly possible to know something?

I found myself pondering these questions while standing thigh deep in marsh mud and spadderdock, having just looked back along my transect at the wide swath of destruction I'd left in my wake. The sun had turned the marsh into a sauna and you could almost hear the cattails and arrow arum panting in the heat. With sweat rolling down my arms and my skin complaining of one hundred little stings, courtesy of the patch of cutting grass I had fallen into, I'd be the first to admit it was an odd time for reflection. These were strange musings also, since sedimentation rates in freshwater tidal marshes are a far cry from quantum particle behavior, which was what initially sparked discussion of the observer effect. But looking back at the trail of broken stems and shredded leaves that suggested a hippopotamus had blundered through instead of a 120-pound girl, I couldn't help but wonder if I was causing more harm than good. After all, I wanted to understand the marsh, not destroy it.

Other scientists have faced the same dilemma, and in matters much more serious than a couple of trampled plants. From toxicologists to medical scientists to anyone who has worked in an animal lab, we must constantly ask ourselves if the ends justify the means. This is not a new moral question and most times the answer is "yes"; the good for the many that will come from the research overshadows the sacrifices of the few needed to get there.

But what about the observer effect? Doesn't this change the situation entirely? What if the question was, "do the ends justify the means, even if the ends might be flawed?" How many would answer yes to that? Take my own situation. I wanted to know how plant morphology affects the rate at which sediment settles to the bottom of the marsh. My results would help create a model that would ultimately predict whether freshwater marshes could survive rising sea levels. But sedimentation is a complex phenomenon, influenced by hydrology, sediment load, plant composition, and a myriad of other factors too numerous to list. Like the proverbial flutter of a butterfly wing that eventually spawns a hurricane, a small change in any of those factors might have far-reaching effects. And I had just ripped up 50 meters of marsh along the very same line where I was taking measurements. How could I think for an instant that my presence was not affecting the variables I was measuring?

In science this is called "error," and there are tricks and computations used to minimize them, including mathematical, mechanical, and other more creative techniques that are probably seldom mentioned in the materials and methods section. This in itself suggests the answer is still, "yes," that it is still worth it and that the results we get are valuable, be they flawed or limited.

But in my own case? Luckily I am spared from having to answer. When I returned to my study site the next day the path of destruction I had left had disappeared. The mud had settled, the plant stalks had unbent, and the marsh was an unbroken sea of green once more. Of course that is not the end of the issue. My results might still be compromised and I will never stop asking myself whether the ends justify the means, but still I am not too concerned. Who knows what will happen in projects to come, but that day it seemed the marsh was giving me a message. I should worry about my own data — the marsh could take care of itself.

Keala Cummings wrote this essay for an ethics seminar as part of her REU fellowship at the UMCES Chesapeake Biological Laboratory. She is currently a senior at Scripps College.