Living with uncertainty

It may seem obvious, but it cannot be said often enough: science is not merely a list of Things We Know.

Science includes all our knowledge about the physical world, and our understanding of its processes and mechanisms, but perhaps most important of all is the scientific method. It is the method of finding things out.

It involves rigorously questioning what one sees, watching it unfold while carefully observing and measuring it, describing the how and why without bias. Then letting others challenge our perception, and put our ideas to the test.

The scientific method also involves being aware of the errors that can creep into this process, and constantly testing our laws, theories, observations, and their accuracy. It involves being aware of the limits of this knowledge for a realistic grip on the Things (we think) We Know.

The history of the application of the scientific method also shows that the context in which we understand things changes regularly. One obvious example is the long-held belief of the Earth as the centre of the Universe which was later turned on its head.

Grappling with knowledge

So what are the unknowns and errors that we must be aware of in the scientific process?

There several types of unknowns. At TWDK, we will deal only with scientific uncertainty in an experimental result:

– The facts that we haven’t come across yet and whose existence we cannot predict or are unaware of – the Things (we don’t know that) We Don’t Know

– The gaps in our knowledge that we are seeking the answers to – the Things (we know that) We Don’t Know

– The inaccuracies in our existing knowledge – the Things We Don’t (quite) Know (even if we thought we did)

Delve deeper into types of unknowns.

Here at TWDK, we seek to deal with the second and third type.

Let us try and tackle the third type of unknown: the uncertainty implicit in what we do know, or rather, Things (we think) We Know.

How do we come to know?

We use experimental observation to measure what we see objectively and precisely. There are limits to the precision of our instruments, the techniques that we use, and even to our own objectivity. These shortcomings bring ‘uncertainty’ into scientific experiments.

To narrow in on reality, we must continuously improve our theories and models, instruments and experiments. To do this we must understand where these uncertainties creep in, and devise ways to overcome them.

Knowing what we don’t know

Uncertainty must be dealt with in each field, at each level, in its own way. There are several stages where it may creep in.

Assumptions may be have been made before experimentation. Delve deeper into Occam’s Razor.

Sampling errors may be encountered when dealing with a small sample (piece or amount) of something too large to measure all at once, such as a cup of water from a river. How can we be sure this sample is representative of the bigger picture? If this cup had a lot of pollutants in it, how can we be certain are we that the whole river does? Taking a bigger sample, or many little samples, can improve confidence in our results.

Any experimental observation will have an error associated with it. These errors may originate from fundamental physical limits that limit the accuracy of the measurement, instrument inaccuracy, deficiencies in the measurement technique, or inadequacies in analysis, among other factors. These may be represented as an error bar on a graph or a plot, or within disclaimers. The relative error, or the magnitude of the error (difference between the exact value and the appoximation) as compared to the magnitude of the exact value, is important too. Delve deeper into error.

The failure to replicate can raise its head, even for strong results. In such cases, replication of the experiment does not provide the same result (within the expected margin of error).

Readers are invite to tell leave comments and tell me if I’ve missed anything in the list above.

Dealing with uncertainty

It is very hard to maintain the awareness of these shortcomings routinely as some of this information is unavailable at times. To complicate matters further, popular science writing may not include any mention of uncertainties in findings at all. There are also examples of cases where statistics are deliberately manipulated to favour a certain result, or obfuscated to communicate a different inference.

Ultimately, all known scientific facts rest upon uncertainties. This doesn’t automatically mean they’re wrong, but it may be possible for us to improve upon them. This awareness is extremely important for scientific literacy. This is why there is a need for skepticism, and to make space in our minds for Things We Don’t Know.

There are things that we can do to minimise error in our observations or measurements. We’ll deal with this in another blog post.

This is a post for Things We Don’t Know, a new project that’s also on blogger and Twitter.

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6 thoughts on “Living with uncertainty

  1. maxbabi says:

    Hi Amruta, a very cogent article -however risking the possibility of sounding naive and unscientific, I am driven to express my own doubts, at a very fundamental level. When we were in college, aeons ago, we were taught Dalton’s theory that the atom is the last divisible particle of matter. Soon, it was clear, the atom was composed of sub-atomic particles, which are by now 256 in number with strange names and stranger properties. That drags in a wild menagerie of uncertainty beasts. Also, physics tells us the atom for the most part is just an empty shell, perhaps 98% empty space where the nucleus is surrounded by superfast electrons whizzing past to seem like a cloud, here there and everywhere at every moment… now all this -is it certain, by any means? The empty space itself, makes every thing uncertain… please comment.

    • mehtaamruta says:

      Hi Max

      Well your question would be better answered by somebody doing research in that field itself. But one thing we must not forget when doubting what we know is that we do know some things to a certain degree of certainty, and that we’ve been experimenting with certain models for a long time.

      Also the model that you mention of is an archaic one. For instance, one thing we understand is that electrons are spread around the nucleus in a ‘smear’ rather than as distinct particles with defined orbits.

      Honestly, thinking about the electron itself sends me into a tizzy: a wave-like smear with a certain charge that can jump about and attain different levels of energy…. it’s hard to grasp completely.

      Not sure my reply helps though 🙂 I’m hoping a specialist will see this and respond.

      • maxbabi says:

        Hi Amruta,

        You seem to have missed seeing the forest for the woods.
        The electron being a particle or a wave or a smear or a ‘cloud’ (as I said) is not at all the central point of my comment.
        Uncertainty is.

        Science has been uncertain, beginning with the sub-atomic particles to the composition of the universe/s…. after 40 years in science, I can count the certainties on my fingers but there is no end to uncertainties.

        This post is not aimed at you. It is aimed at mankind, whose faith in cynical science which rejects most of what we experience ( mind-reading, un-explainable coincidences, serendipity -a topic on which I have done 5 successful workshops, synchronicity, and intuition : the more you study human nature via psychology or psychiatry the more confused you get… we know nothing about the human brain either…) Like Einstein said, science is lame without religion (he meant spirituality, not organised religion which all of us are allergic to) and religion is blind without science.

        The whole approach of science has been on a path full of uncertainties. There is total lack of spirituality, which is at loggerheads with science, which is wrong. They should go hand in hand.

        Thank you,


      • mehtaamruta says:

        I invite you to re-examine your first comment and this subsequent response, Max. There is at least one contradiction in what you’ve written. Also, this is not a discussion about religion or spirituality. Thanks.

  2. Barns says:

    I have nothing of value to personally add to either the post or the comments – I cannot call myself a scientist – but you might be interested in this piece on uncertainty and ‘unknown unknowns’ in the New York Times:

    It’s worth reading in entirety.

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