Friday 30 March 2007

Pic of the day: And they will like change even more in the future, if any.

Facts change

When I was young, there was a saying that the half-life of facts was only 20 years. Half-life, in scientific terms, has nothing to do with games or zombies. It is the time a radioactive element needs to change, through its radiation, half of its atoms to another element. For each individual atom, the time of decays seems random. But when we have many atoms, mysteriously the rate of decay can be measured very precisely. When the time we call half-life has gone, half the substance has been transformed, although we cannot predict which individual atoms. When the same time has gone again, mysteriously the second half has not changed, but only half of it again. How do they know they are only half as many? Or, if a million atoms decayed the first year, why don't another million decay the next year too? Actually it makes sense when you understand it, but it is still fun to ask people and see them flail.

Anyway! Like radioactive atoms, facts also have a half-life rather than a definite lifetime. After a certain length of time, some of them have changed, but it is hopeless to say beforehand which. For all I know, the half-life of facts may be one of the facts that have changed. If so, it's a safe bet that the current half-life is shorter.

So let us look at some of the facts I took for granted but have changed over the last few years:

Health:

Cholesterol is dangerous for your heart. Avoid food that is high in cholesterol, especially eggs. -- Not unless you suffer from a rare metabolic disease. For the rest of us, the body makes more cholesterol if you eat less, so the content in your blood is the same. You can several eggs a day before the cholesterol becomes a problem: Typical production in the body is 1 gram a day, while typical food intake is 0.2-0.3 gram a day. Total fat intake however influences the level of cholesterol in the bloodstream. The fatty plaque on the artery walls is not caused simply by excess cholesterol, but depends on the balance between two lipoproteins. One of them (LDL, low density lipoprotein) deposit cholesterol, another (HDL, high density lipoprotein) carries it away. In addition, the formation of plaques may partially have immunological reasons; the same bacterium that causes stomach ulcer is suspected. Generally, eating cholesterol has no effect on your health.

Animal fat is bad, plant fat is OK, and fish fat is good. --Not anymore. Yes, Omega-3 fatty acids are still good for you in moderation. But certain plant fats are now considered even better, particularly flax oil (for women only), olive oil and nut oil (unless you are allergic to nuts, of course). On the other hand, palm oils are almost toxic, second only to the dreaded trans fats which are now being outlawed in some countries. Meanwhile, seal fat contains Omega- 3 as well, while milk fat contains CLA which reduces the risk of obesity as well as protecting against some cancers.

Overweight causes lifestyle diseases such as late-onset diabetes, atherosclerosis, heart infarct and hypertension. -- Not directly. A very low level of physical activity seems to precede these symptoms. The same lack of activity will, with a normal diet and common genes, also cause obesity. Obesity in turn will make it less comfortable and more embarrassing to move about at a good speed, but if you do it anyway you will reap the same benefits as the slimmer joggers. Just be sure to start before you have taken permanent damage, and don't go wild: Being obese is like exercising in armor and with a backpack. Get a pulse clock and check that you don't overdo it.

Stiffness after training is caused by lactic acid accumulating in the muscles. To avoid it, be sure to stretch out after exercise. --Lactic acid has been tried and found Not Guilty. It is not a poison but a source of energy, an intermediate stage in breaking down sugar. It is metabolized as soon as the cell gets enough oxygen, which is as soon as you have caught your breath again. Stiffness comes from tearing over small fibers in the muscles, and is caused by not warming up sufficiently, or exercising harder than your body was ready for. By the time you stretch out, it is too late, and if you stretch too hard it may get worse. The best cure is to rest the muscles completely as soon as possible after you finish your exercise.

Psychology:

Bullies have low self-esteem. To raise a happy, well-adjusted child, be sure to always praise them and never shame them. -- Bullies actually have extremely high self-esteem. They also report being more popular, prettier and more attractive than others. The only of these properties that is verified by their classmates or coworkers is that they are very good at making friends and initiating romantic relationships, but their friendships and romances tend to be short and end badly, for which the bullies naturally blame the other part, seeing as they have a high self-esteem and thus find no fault in themselves. It is somewhat disconcerting to discover this just after we have intentionally raised a whole generation of these people.

Autism is caused by vaccines, more exactly vaccines with mercury in them. --Barely even wrong, this theory is based on a study of a handful of patients, by a non-independent researcher. Larger studies, including a nationwide Danish study, disprove it. Actually, the vaccines in question were never used in Scandinavia, and we have the same increase in autism as the countries where such vaccines are used.

***

I was about to write a section about cosmology too, but realized that the facts are mostly not changed, just gone. While we used to think we knew what the universe was made of and where it went, possibly even where it came from, we now can only account for less than 5% of it, some cosmic constants seem to change over time (including the speed of light) albeit just a little, and the most likely prospect right now is that the universe is going to explode again in a super-big-bang. But we don't really know until we find out what the rest of it is made of, if ever. Perhaps we'll all die trying.

Oh, and something that I have only learned recently is that there is a difference (not conflict) between facts and truth. But that is entirely outside the scope of this entry.