The physics of driving

This is quite a departure, I know, but one of my hobby-horses is how little people know about the physics of driving. Unlike our man-made road rules, the laws of nature are unbreakable, so a rudimentary knowledge can be useful.

But what prompted me to write this post was a road test I read of the new, upmarket Infiniti Q50 in EVO Australia (March 2014). The big-selling feature of the Infiniti Q50 is its so-called ‘direct adaptive steering’; a world first, apparently for a production car (as opposed to a prototype or research vehicle). It’s a totally ‘fly-by-wire’ steering system, so there is no mechanical connection between the helm and the front wheels. Personally, I think this is a dangerous idea, and I was originally going to title this post, rather provocatively, “A dangerous idea”. Not surprisingly, at least to me, the road-tester found the system more than a little disconcerting when he used it in the real world. It was okay until he wanted to push the car a little, when the lack of feedback through the wheel made him feel somewhat insecure.

There are gyroscopic forces on the front wheels, which naturally increase with cornering force and can be felt through the  steering wheel. The wheel weights up in direct proportion to this force (and not the amount of lock applied as some might think). In other words, it’s a linear relationship, and it’s one of the major sources of determining the cornering force being generated.

I should point out that the main source of determining cornering force is your inner ear, which we all use subconsciously, and is why we all lean our heads when cornering, even though we are unaware of it. It’s the muscle strain on our necks, arising from maintaining our inner ear balance, that tells us how much lateral g-force we have generated. On a motorcycle, we do the opposite, keeping our heads straight while we lean our bodies, so the muscle strain is reversed, but the effect is exactly the same.

Therefore, you may think, we don’t need the steering wheel’s feedback, but there is more. The turn-in to a corner is the most critical part of cornering. This was pointed out to me decades ago, when I was a novice, but experience has confirmed it many times over. Yes, the corner can change radius or camber or both and you might strike something mid-corner, like loose gravel, but, generally, if the front wheels grip on entry then you know they will grip throughout the rest of the corner. This is the case whether you’re under brakes or not, wet or dry surface. It’s possible to loosen traction with a heavy right foot, but most cars have traction control these days, so even that is not an issue for most of us. The point is that, if the front wheels grip on turn-in, we ‘feel’ it through the steering wheel, because of the gyroscopic relationship between cornering force and the weight of the wheel. And cornering force is directly proportional to the amount of grip. The point is that without this critical feedback at turn-in, drivers will be dependent on visual cues to work out if the car is gripping or not. What’s more, the transition from grip to non-grip and back won’t be felt through the wheel. If this system becomes the engineering norm it will make bad drivers out of all of us.

While I’m on the topic, did you know that at twice the speed it takes four times the distance to pull up to a stop? Perhaps, you did, but I bet no one told you when you were learning to drive. The relationship between speed and braking distance is not linear – braking distance is proportional to the speed squared, so 3 times as fast takes 9 times the distance to stop. This is independent of road surface, tyres and make of car – it’s a natural law.

Another one to appreciate is that at twice the speed, changing direction is twice as slow. There is an inverse relationship between speed and rate of change of direction. This is important in the context of driving on multi-lane highways. A car travelling at half the speed of another – that’s overtaking it, say – can change direction twice as fast as the faster car. This is also a law of nature, so even allowing for superior tyres and dynamics of the faster car, the physics is overwhelmingly against it. This is why the safest speed to travel on multi-lane highways is the same speed as everyone else. An atypically slow car, in these circumstances, is just as dangerous (to other motorists and itself) as an atypically fast car.

Addendum: I also wrote a post on the physics of riding a motorcycle.

Afterlife belief – a unique human condition

Recently I’ve been dreaming about having philosophical discussions, which is very strange, to say the least. And one of these was on the topic of the afterlife. My particular insight, from my dream, was that humans have the unique capacity to imagine a life and a world beyond death. It’s hard to imagine that any other creature, no matter its cognitive capacity, would be able to make the same leap. This is not a new insight for me; it’s one my dream reminded me of rather than initiated. Nevertheless, it’s a good starting point for a discussion on the afterlife.

It’s also, I believe, the reason humans came up with religion – it’s hard to dissociate one from the other.  Humans are more than capable of imagining fictional worlds – I’ve created a few myself as a sometime sci-fi writer. But imagining a life after death is to project oneself into an eternal continuity, a form of immortality. Someone once pointed out that death is the ultimate letting go of the ego, and I believe this is a major reason we find it so difficult to confront. The Buddhists talk about the ‘no-self’ and ‘no attachments’, and I believe this is what they’re referring to. We all form attachments during life, be it material or ideological or aspirational or through personal relationships, and I think that this is natural, even psychologically necessary for the most part. But death requires us to give all these up. In some cases people make sacrifices, where an ideal or another’s life takes precedent over one’s own ego. In effect, we may substitute someone else’s ego for our own.

Do I believe in an afterlife? Actually, I’m agnostic on that point, but I have no expectation, and, from what we know, it seems unlikely. I have no problem with people believing in an afterlife – as I say, it’s part of the human condition – but I have a problem when people place more emphasis on it than the current life they’re actually living. There are numerous stories of people ostracizing their children, on religious grounds, because seeking eternal paradise is more important than familial relationships. I find this perverse, as I do the idea of killing people with the promise of reaching heaven as a reward.

Personally, I think it’s more healthy to have no expectation when one dies. It’s no different to going to sleep or any other form of losing consciousness, only one never regains it. No one knows when they fall asleep or when they lose consciousness, and the same applies when one dies. It leaves no memory, so we don’t know when it happens. There is an oft asked question: why is there something rather than nothing? Well, consciousness plays a big role in that question, because, without consciousness, there might as well be nothing. ‘Something’ only exists for ‘you’ while you are alive.

Consciousness exists in a continuous present, and, in fact, without consciousness, the concepts of past present and future would have no meaning. But more than that, without memory, you would not even know you have consciousness. In fact, it is possible to be conscious or act conscious, whilst believing, in retrospect, that you were unconscious. It can happen when you come out of anaesthetic (it’s happened to me) or when you’re extremely intoxicated with alcohol or when you’ve been knocked unconscious by a blow. In these admittedly rare and unusual circumstances, one can be conscious and behave consciously, yet create no memories, so effectively be unconscious. In other words, without memory (short term memory) we would all be subjectively unconscious.

So, even if there is the possibility that one’s consciousness can leave behind the body that created it, after corporeal death, it would also leave behind all the memories that give us our sense of self. It’s only our memories that give us our sense of continuity, and hence our sense of self.

Then there is the issue of afterlife and infinity. Only mathematicians and cosmologists truly appreciate what infinity means. The point is that if you have an infinite amount of time and space than anything that can happen once can happen an infinite number of times. This means that, with infinity, in this world or any other, there would be an infinite number of you and me. But, not only am I not interested in an infinite number of me, I don’t believe anyone would want to live for infinity if they really thought about it.

At the start, I mentioned that I believe religion arose from a belief in the afterlife. Having said that, I think religion comes from a natural tendency to look for meaning beyond the life we live. I’ve made the point before, that if there is a purpose beyond the here and now, it’s not ours to know. And, if there is a purpose, we find it in the lives we live and not in an imagined reward beyond the grave.