As for the fictional effects of gamma-ray photons,
middle-aged readers may recall that the recent Spiderman movies updated the neo-techno-phobia: a genetically modified spider was the culprit, not a radioactive one as of old. I recall that according to a National Radiological Protection Board booklet in the 1980s, if memory serves well, I could have stood next to my lead-lined (10 +/- 5 mm thick?) safe in my radioactivity-metrology lab all morning and got a lower dose of ionizing radiation than by flying to Spain at high altitude. Frightening people is so easy! Is there any way to shame the commercial popular culture merchants into trying something more difficult, like calming readers down? Oh, who am I kidding? I may have to try writing “mundane SF” myself.

As for the fictional effects of gamma-ray photons,
middle-aged readers may recall that the recent Spiderman movies updated the neo-techno-phobia: a genetically modified spider was the culprit, not a radioactive one as of old. I recall that according to a National Radiological Protection Board booklet in the 1980s, if memory serves well, I could have stood next to my lead-lined (7 +/- 5 mm thick?) safe in my radioactivity-metrology lab all morning and got a lower dose of ionizing radiation than by flying to Spain at high altitude? Frightening people is so easy! Is there any way to shame the commercial popular culture merchants into trying something more difficult, like calming readers down? Oh, who am I kidding? I may have to try writing “mundane SF” myself.

And the 4×4 people will have to spend an extra 20 minutes in the gym each (which will involve driving to the gym and back)…..

e.g. volvos or bmws (‘volvo drivers’ appear to have been replaced by ‘bmw drivers’ for the most arrogant and annoying on the road these days).

Or did you just add some anecdotal evidence to make the story sound good?

The intention was neither precision nor fastidious calculation, infact quite the opposite.

I deliberately chose ball park figures: specifically an over-heavy bicycle and quarter weight car (assuming full occupancy and per capita for comparison), as these should bias any estimate in favour of the opponent.

Thus regarding acceleration etc, you no longer need bother calculate it to get a rough idea once you realise you have a less efficienct engine moving much more weight around to achieve the same end.

The point is that a little scientific literacy goes a long way in terms of b**lshit filtering.

You’ll also need to calculate the extra CO2 used by all the cars having to slow down, wait, then accelerate past the 4 bikes, over 38 minutes….

Also as a motorcyclist well over half of the near misses i’ve had have been with 4×4′s… just look for the ones with knuckle marks in the door panels. So you can chalk up extra usage of rubber – for braking to avoid them and ambulance usage both…. plus of course new wing mirrors that they will inevitably replace even thought they don’t appear to use them which is what leads to their removal by irate bikers.

Engine noise is a factor in accidents… which is why bikers put louder exhausts on their bikes so car drivers might hear them even if they don’t see them.

According to Gary Kamen’s book “Foundations Of Exercise Science” walking uses 0.75 calories per kg of body weight per km, cycling uses 0.15 calories per kg per km. However the maximum efficiency of cylcing is approx. 29% and walking slightly higher. He also states that cycling is much more efficient than a car.

Also 15Kg is a tad on the heavy side for a bike. A Galaxy tourer is 1.5 Kg lighter than that and that is a fairly heavy bike. Also a car that weights 250 Kg? Even a Ford Fiesta 1.6 has a kerb weight of 1100Kg.

I haven’t had time to browse the relevent literature fully. However it seems improbable that a biological engine moving 85kg around the place (70kg man plus 15kg bike) is going to be no more efficient than a heat engine moving 320kg (1/4 of 1 tonne care plus 70kg man) about the place.

‘Physics literacy, energy and
the environment’,Art Hobson, Physics Education, March 2003, p 109

..is worth a read in this regard.

On a more serious topic: It was mentioned that we obviously don’t eat coal for breakfast. However, I don’t think we can claim that our food consumption only recycles CO2 and is not making any net contribution to CO2 in the atmosphere. A lot of fossil energy goes into agriculture itself, transport of food, cooking etc.
I’d be very interested to see some proper calculations how CO2 efficient we, as human beings are. Obviously this also depends on what we eat. I assume the fact that, if we walk, we only have to move our own body weight (and not the car as well) would make us quite fuel efficient. Do our bodies generally convert energy more efficiently into movement (instead of heat) than a car? How efficient is cycling compared to walking or running?

Maybe there are some exercise physiologists on this board who know the answers to my questions?

Anyway, it’s good to see them promoting car sharing. Have they amalgamated with the Association of British Passengers?

Having said that, one car advert apparently now sounds an alarm when something pops up in front of you, such as a donkey, although these days you can’t tell if something in a car advert is real or not, which I think (and I think I’ve said) is because adverts with reckless or impossible driving were banned unless the advert was made to look obviously like a cartoon.

Those calculations re: CO2 emissions neglect to mention that the CO2 emitted by cars is in effect ‘new’ CO2, having been locked away underground for millions of years. The CO2 emitted by cyclists is merely recycled from the atmosphere through the food chain etc, and hence isn’t making a net contribution to atmospheric CO2 levels.

Therefore the calculations,although interesting, are irrelevant.