The root of the obesity epidemic is in our past
Carl Zetie highlights the issue of those who say that a change of attitudes, not the use of weight-loss drugs, is the way to tackle obesity (Letters, 6 July).
As has been pointed out many times, one reason why our ancestors avoided this problem was the struggle they had in accessing food. Hunting ruminants with horns could be lethal, so carnivores like us would only undertake this activity when hunger required it. Now, with a readily available supply of cheap food containing large quantities of sugar, salt, fat, artificial flavourings and preservatives, our species can consume calories with almost no effort: simply unwrap ready meals and use the microwave.
Species change behaviour to fit the ecological niche that has been enabled, previously by nature and now, in the case of Homo sapiens, by our own ingenuity. We have supercharged the rate of ecological change. Also, highly processed foods tend to be addictive.
To overcome this problem, we need to teach the very young why they might become obese and how this might be avoided. We also need to remove the temptation 鈥� the production of highly processed foods and their easy accessibility.
The alternative is to continue down an evolutionary black hole we have created, which could be fatal.
Maybe the universe isn't flat or finite after all (1)
I don’t think the universe is infinite, but instead is in the form of the “surface” of a four-dimensional Euclidean hypersphere, so is finite. Nor do I think our universe is the only one: there may be other “bubbles” like ours in the wider cosmos, of which our universe is only one part. To say the universe is flat because nearby observations appear flat, so this therefore applies on a large scale too, is just as ridiculous as saying Earth must be flat because it looks like that on a small scale (29 June, p 31).
Maybe the universe isn't flat or finite after all (2)
Is the universe infinite? Space and time are assumed to have begun at the big bang. So, if our universe is expanding, it would need infinite time to become infinite in extent. Yet current theory maintains a beginning 13.8 billion years ago.
How to grapple with a conscious cosmos
You ask: Is the universe conscious? The answer depends on what is meant by “conscious”. If the definition is an operational one, the question can be settled by observation and experiment. If not, well, you can play more or less interesting semantic games (29 June, p 38).
I think the nominal -ness suffix in “consciousness” has misled a lot of thinkers, me included. A -ness word refers to an entity or to a trait. It doesn’t refer to a process or event. Yet (after much thought) it seems obvious to me that any investigation into consciousness must begin with the observation that it exists only while it is happening. Like rain. Or a thought. Or a life.
The big problem with life beyond Earth
In your look at life in the universe, you say that almost all the stars that will ever exist have already been born, and they have been around long enough for life to arise on planets that orbit them. But we don’t know that they have been around long enough for life to come about in this way. We only have our own world as an example, and we have no idea how the amazingly complicated systems involved in even the simplest forms of life came about (29 June, p 33).
Unless and until someone finds a plausible scenario and calculates the probable rate at which this would occur, we must admit our ignorance on this point.
Can time flow backwards in some areas of space?
Chanda Prescod-Weinstein comments on the idea that the arrow of time is linked to increasing entropy. What this approach seems to miss is that, while in most systems entropy will almost always increase, there is a very small chance that a system will become more orderly, with lower entropy, just as a result of random motion. Especially if the system consists of just a few molecules. As the universe is big, these long shots will be happening somewhere all the time (29 June, p 20).
Does this mean that, in small, random pockets of space, time’s arrow goes backwards? That doesn’t seem to make much sense. I would prefer to view our universe as a system of mathematical equations, where t for time is a parameter in some of those equations. This parameter causes change to happen in our universe. Without change, there would be no experience of any kind of reality.
Getting radical about electric vehicles
In your story about getting UK climate goals on track, economist Michael Pollitt mentions the need to reduce the weight and size of vehicles. Why would anyone who wants to protect the environment design an EV that weighs more than 2 tonnes, leading to increased energy demand and road damage(22 June, p 10)?
Far better to use wind farms to make synthetic fuel from air and seawater to run a tiny onboard generator. This would recharge a motor. Such a car would achieve 120 miles per gallon with no carbon emissions, and without damaging the environment to make batteries.
Twerk your way to a better back
On exercises to stave off lower back pain, I discovered that regular hip waggling (twerking?) during tooth cleaning with my 2-minute cycle electric brush resulted in the pain completely disappearing. The only downside is that I have to make sure no one sees me 鈥� even at 90, I look incredibly sexy(29 June, p 15)!
No one should be getting on an aircraft
Yes, carbon offsets for air travel don’t work. I, for one, won’t get on a plane until that changes. If we want to mitigate the worst effects of climate change, no one should be getting on aircraft. But people seem to feel entitled to fly to see threatened areas of the natural world for themselves before they disappear. I have actually read articles that assert the need to get to these places soon. It is obscene (Letters, 8 June).