Keith S. Taber
I have recently posted on the blog about having been viewing some of the court testimony being made available to the public in the State of Minnesota v. Derek Michael Chauvin court case (27-CR-20-12646: State vs. Derek Chauvin).
[Read 'Court TV: science in the media']
I was watching the cross examination of expert witness Dr Martin J. Tobin, Professor of Pulmonary and Critical Care Medicine by defence attorney Eric Nelson, and was intrigued by the following exchange:
Now you talked quite a bit about physics in your direct testimony, agreed?
Yes
And you would agree that physics, or the application of physical forces, is a constantly changing, er, set of circumstances.
I did not catch what you said.
Sure. You would agree with me, would you not, that when you look at the concepts of physics, these things are constantly changing, right?
Yeah, all of science is constantly changing.
Constant! I mean,
Yes.
in milliseconds and nanoseconds, right?
Yes.
And so if I put this much weight [Nelson demonstrating by shifting position] or this much weight [shifting position], all of the formulas [sic] and variations, will change from second to second, from millisecond to millisecond, nanosecond to nanosecond, agreed.
I agree.
Similarly, biology sort of works the same way. Right?
Yes.
My heart beats, my lungs breathe [sic], my brain is sending millions of signals to my body, at all times.
Correct.
Again, even, I mean, faster than the speed of light, right?
Correct.
Millions of signals every nanosecond, right?
Yes.
Day 9. 27-CR-20-12646: State vs. Derek Chauvin
Agreeing – but talking about different things?
The first thing that struck me here concerns what seems to me to be Mr Nelson and Dr Tobin talking at cross-purposes – that neither participant acknowledged (and so perhaps neither were aware of).
I think Nelson is trying to make an argument that the precise state of Mr George Floyd (who's death is at the core of the prosecution of Mr Chauvin) would have been a dynamic matter during the time he was restrained on the ground by three police officers (an argument being made in response to the expert's presentation of testimony suggesting it was possible to posit fairly precise calculations of the forces acting during the episode).
This seems fairly clear from the opening question of the exchange above:
Now you talked quite a bit about physics in your direct testimony, agreed? … And you would agree that physics, or the application of physical forces, is a constantly changing, er, set of circumstances.
However, Dr Tobin does not hear this clearly (there are plexiglass screens between them as COVID precautions, and Nelson acknowledges that he is struggling with his voice by this stage of the trial).
Nelson re-phrases, but actually says something rather different:
You would agree with me, would you not, that when you look at the concepts of physics, these things are constantly changing, right?
['These things' presumably refers to 'the application of physical forces', but if Dr Tobin did not hear Mr Nelson's previous utterance then 'these things' would be taken to be 'the concepts of physics'.]
So, now it is not the forces acting in a real world scenario which are posited to be constantly changing, but the concepts of physics. Dr Tobin's response certainly seems to make most sense if the question is understood in terms of the science itself being in flux:
Yeah, all of science is constantly changing.
Given that context, the following agreement that these changes are occurring "in milliseconds and nanoseconds" seems a little surreal, as it is not quite clear in what sense science is changing on that scale (except in the sense that science is continuing constantly – certainly not in the sense that canonical accounts of concepts shift at that pace: say, in the way Einstein's notions of physics came to replace those of Newton).
In the next exchange the original context Nelson had presented ("the application of physical forces, is … constantly changing") becomes clearer:
And so if I put this much weight [Nelson demonstrating by shifting position] or this much weight [shifting position], all of the formulas and variations, will change from second to second, from millisecond to millisecond, nanosecond to nanosecond, agreed.
I agree.
As a pedantic science teacher I would suggest that it is not the formulae of physics that change, but the values to be substituted into the system of equations derived from them to describe the particular event: but I think the intended meaning is clear. Dr Tobin is a medical expert, not a physicist nor a science teacher, and the two men appear to be agreeing that the precise configurations of forces on a person being restrained will constantly change, which seems reasonable. I guess that is what the jury would take from this.
If my interpretation of this dialogue is correct (and readers may check the footage and see how they understand the exchange) then at one point the expert witness was agreeing with the attorney, but misunderstanding what he was being asked about (how in the real world the forces acting are continuously varying, not how the concepts of science are constantly being developed). Even if I am right, this does not seem problematic here, as the conversation shifted to the intended focus quickly (an example of Bruner's 'constant transnational calibration' perhaps?).
However, this reminds me of interview</div><div class=glossaryItemBody>Research interviewing involves a class of techniques for collecting data based upon engaging informants in conversations with various levels of structuring<em>Read more about research interviews</em><br/></div>" href="https://science-education-research.com/reference/site-glossary/interview/" target="_blank" data-mobile-support="0" data-gt-translate-attributes='[{"attribute":"data-cmtooltip", "format":"html"}]' tabindex='0' role='link'data-bgcolor="#e8e8e8"data-tcolor="#73874d">interviews with students I have carried out (and others I have listened to undertaken by colleagues), and of classroom episodes where teacher and student are agreeing – but actually are talking at cross purposes. Sometimes it becomes obvious to those involved that this is what has happened – but I wonder how often it goes undetected by either party. (And how often there are later recriminations – "but you said…"!)
Simplifying biology?
The final part of the extract above also caught my attention, as I was not sure what to make of it.
My heart beats, my lungs breathe, my brain is sending millions of signals to my body, at all times.
Correct.
Again, even, I mean, faster than the speed of light, right?
Correct.
Millions of signals every nanosecond, right?
Yes.
How frequently do our brains send out signals?
I am a chemistry and physicist, not a biologist so I was unsure what to make of the millions of signals the brain is sending out to the rest of the body every nanosecond.
I can certainly beleive that perhaps in a working human brain there will be billions of neutrons firing every nanosecond as they 'communicate' with each other. If my brain has something like 100 000 000 000 neurons then that does not seem entirely unreasonable.
But does the brain really send signals to the rest of the body (whether through nerves or by the release of hormones) at a rate of nx106/10-9 s-1 ("millions of signals every nanosecond"), that is, multiples of 1015 signals per second, as Mr Nelson suggests and Dr Tobin agrees?
Surely not? Dr Tobin is a professor of medicine and a much published expert in his field and should know better than me. But I would need some convincing.
Biological warp-drives
I will need even more convincing that the brain sends signals to the body faster than the speed of light. Both nervous and hormonal communication are many orders of magnitude slower than light speed. The speed of light is still considered to be a practical limit on the motion of massive objects (i.e., anything with mass). Perhaps signals could be sent by quantum entanglement – but that is not how our nervous and endocrine systems function?
If Mr Nelson and Dr Tobin do have good reason to believe that communication of signals in the human body can travel faster than the speed of light then this could be a major breakthrough. Science and technology have made many advances by mimicking, or learning from, features of the structure and function of living things. Perhaps, if we can learn how the body is achieving this impossible feat, warp-drive need not remain just science fiction.
A criminal trial is a very serious matter, and I do not intend these comments to be flippant. I watched the testimony genuinely interested in what the science had to say. The real audience for this exchange was the jury and I wonder what they made of this, if anything. Perhaps it should be seen as poetic language making a general point, and not a technical account to be analysed pedantically. But I think it does raise issues about how science is communicated to non-experts in contexts such as courtrooms.
This was an expert witness for the prosecution (indeed, very much for the prosecution) who was agreeing with the defence counsel on a point strictly contrary to accepted science. If I was on a jury, and an expert made a claim that I knew was contrary to current well-established scientific thinking (whether the earth came into being 10 000 years ago, or the brain sends out signals that travel faster then the speed of light) this would rather undermine my confidence in the rest of their expert testimony.
