The runaway train problem, again
Unrealistic questions are likely to produce unrealistic answers. Unless one is an employee of the railway company, it is implausible that one could ever know enough to decide that changing a set of points (a switch in US parlance) might save lives. And it is even more implausible that tossing a person, no matter how obese, onto the tracks will slow a train sufficiently to alter the damage it will do. Besides, the questions seem to assume one is operating in a legal vacuum.
If I do nothing, the worst I can be accused of is cowardice. If I intervene in any way, no matter how well intentioned, I may well find myself charged with murder. If you believe a person on the tracks will stop the train, why not jump off the bridge yourself? Or shout at the five people: jump!
Stirling, Western Australia
<b>For the record</b>
鈥� Our review of A Prehistory of the Cloud degraded slightly: JPEG image files commonly degrade when saved (5 September, p 45).
鈥� A current of 1 amp is in fact 6.24150934脳1018 electrons per second (3 October, p 38).
<b>No metal, no cry</b>
Your report that most nearby planets in habitable zones probably have less iron and other metals than Earth (19 September, p 17) may explain the absence of other technological civilisations in our galaxy. With few metals it would surely be difficult for any intelligent life to proceed beyond a stone age. Perhaps we are the first to develop radio.
Bristol, UK
This is where the universe began
Like many, I thoroughly enjoy reading your articles on big scientific questions, particularly in cosmology (5 September, p 30). One thing we can categorically state about the big bang is we know where it happened: here.
Matcham, New South Wales, Australia
My own personal earworm triggers
Ed Hannah reports looking for things that can trigger earworms (Letters, 12 September). This reminds me of having The Ballad of Robin Hood in my head on moving to a new office. I’d not heard it for about 20 years. My office was close to a stairwell. Whenever someone used it, the closing door beat out the rhythm of the song’s opening fanfare.
Recently I have noticed at London’s Waterloo station that the sounds played to tell us the train doors are unlocked make me hum the opening of Prokofiev’s first piano concerto.
Guildford, Surrey, UK
Dark matter that goes 'bonggg'?
鈥� The researchers tell us that macros massive enough to have such an effect are predicted to be so rare that we’d have to wait billions of years to “see” one; those arriving more frequently would have much smaller masses.
Dark matter that goes 'bonggg'?
Thank you for the fascinating postulate that dark matter might be clumps of quarks, “as dense as neutron stars”, and that a teaspoon of them would weigh “as much as a mountain” (22 August, p 28). What happens, however, if one of these macro-particles happens to pass through the NAUTILUS gravitational wave detector’s couple of tonnes of supercooled aluminium like an ultra-dense, hypersonic bullet? I can’t help thinking that the cylinder would do rather more than “deform ever so slightly”.
Sheffield, UK
Liberate mavericks to be creative
Braben asserts that we must either find an alternative to capitalism or “ensure we have an adequate flow of technological change” to meet capitalism’s demand for incessant growth. The former is the only option. Continual growth is an impossibility. Let’s have progress, scientific and intellectual, that would mean valuing equilibrium, not growth, and working towards sustainable development.
Blagnac, France
Liberate mavericks to be creative
Donald Braben recognises that a key obstacle to creative research is the use of peer review as the gold standard for deciding what gets funded (12 September, p 24). Peer review does achieve mediocrity more efficiently.
Most of us could identify one or more scientific mavericks, not all of them academics. I suggest they should be invited to nominate contenders for an award. A panel could then select the recipients. That would circumvent the stultifying grip of peers.
Whitwell, Isle of Wight, UK
Editor's pick: More than one way to slice odds
David Deutsch rightly points out that the conventional view of probability 鈥� that it is the frequency with which a phenomenon is observed 鈥� is very seldom of any real use (3 October, p 30). There are many situations in which we can talk quite meaningfully about probabilities, for which there cannot possibly be a series from which a frequency can be estimated: What is the probability of life on Mars? What is the probability I will die tomorrow? Or even: What is the probability that the 100th decimal digit of pi is 6?
But because 鈥� like so many physicists 鈥� he assumes this is the only kind of probability, he comes to the conclusion that probability itself is a useless concept. In fact there are several ways of viewing probability, of which the most compelling is to regard it as a perception, computed by the brain, rather as colour is computed from wavelength.
Much recent work, recording from neurons in the cerebral cortex, has demonstrated that probability is the language in which neurons talk to each other. At a deeper level, the whole point of the brain is to estimate the probabilities of events in the outside world, including the consequences of our actions, so we are more likely to survive. Probability is subjective.
Cambridge, UK
The runaway train problem, again
Why is anyone surprised by the response to the runaway train problem (26 September, p 36)? The first solution, of throwing a human off the bridge, requires reframing a human as a useful mass. It is this reframing, not the throwing of the mass in the path of the train, which is abhorrent.
I certainly could not achieve it in the available time, and would find it extremely painful given time for leisurely consideration The alternative, of throwing a switch to save five lives at the cost of one, is simple arithmetic which we can do at emergency speed.
Implicit in every morality is the concept that the world is divided into two domains 鈥� people and stuff. People deserve respect, stuff does not. Atrocities occur when people are treated as stuff.
Penwood, Hampshire, UK
Hive mentality or blockchain bloat?
Blockchains seem to mimic with proof of ownership what social insects do with proof of membership. After all these millennia of suffering from top-down despotism, we humans seem finally to be able to attain a hive mentality.
Norwich, New York, US
Hive mentality or blockchain bloat?
Thank you for an excellent article on how the blockchain mechanism could be used in a variety of applications (12 September, p 18). But the blockchain records will expand as transactions are added, especially when they are replicated on all the systems they are used on. How will they be archived?
Dollar, Clackmannanshire, UK
The roots of consciousness
In all 快猫短视频 articles on consciousness I have read, I cannot recall any mention of its role in learning and teaching. As a lecturer, I had to put conscious thought into preparation of my teaching plans and I had to be conscious in order to deliver a lecture. Equally, the students had to pay conscious attention, notwithstanding the joke that defines a lecture as “a process of transferring information from the notes of the lecturer to the notes of the student without it passing through the brains of either”.
Those who downplay consciousness or regard it as a by-product need to demonstrate how teaching and learning could take place without it.
Whittlesey, Cambridgeshire, UK
The roots of consciousness
Paul Mealing writes “For plants, conscious feelings would have no benefit. What’s the point of experiencing fear or pain if one can’t avoid its source?” (Letters, 19 September). But that is an animal-based view. Plants respond rapidly and vigorously to attacks, whether wounds or infection. And some plants move fast 鈥� think of the Venus flytrap.
Even in the unicellular world, organisms avoid unpleasant stimuli and seek out useful ones. At what point one starts to call avoiding unpleasant stimuli “pain” is purely semantic. Fear is more relevant, since it implies memory. Plants have a “memory” of a sort 鈥� they will mount a more rapid attack to a second infection, for example. Molluscs certainly have it. From experience, you can go up to an open giant clam and clip off a little bit of its mantle. It will snap shut, of course, but after that if a human approaches it will snap shut before you get close 鈥� it has learned to fear you.
Sydney, New South Wales, Australia
<b>First class post</b>
So much for David Cameron’s pledge to make his the greenest government yet
Rebekah Mayne to our report that the UK government could face a lawsuit over climate failures (10 October, p 6)
Is it qualia all the way down?
Michael Slezak poses the tantalising question, “If time does not flow, what makes us think it does?” (5 September, p 30). The answer to this question may not lie in physics, but in neuroscience or even in philosophy.
For aeons, both scientists and philosophers have tried to get to grips with what they call the “qualia” of our daily experience 鈥� the direct and seemingly irreducible “redness” of red, the “blueness” of blue. It is hard to believe that such things exist objectively in our universe, so they appear to be “subjective” creations of the brain.
Are time and space simply the canvas upon which qualia play out, or are they themselves qualia, just like red and blue? If so, time and space are subjective. If time is real, then it is perhaps not so surprising that the brain, existing within time, gives us the impression of time. If time is unreal, the mystery of the illusion is a deep one, indeed.
New York, US