Most people with PhDs in physics still don't understand GR. You need not just any old PhD in physics, but one with a research focus somehow related to GR. I have a BS in Physics, but have completed nearly all of the coursework that would be necessary for a physics PhD, plus I'm now a PhD student in engineering, but I don't have the background to understand GR still...

I've taken and understand all of the subjects you list, but the mathematics of GR are still totally a mystery to me. I think you're missing some additional steps/courses?

I'm not intending to give you medical advice, just share controversial ideas that I think are interesting. It's not possible to give enough detail to fully cite my sources and justify my reasoning in a convincing manner within a /. post.

I'm also a long time avid cyclist, but I continued to have serious inflammatory problems with my lower back and left knee that did go away at the same time that I made significant dietary changes (could be a coincidence).

Exercise is well correlated with mortality at a population level, but that doesn't tell you which type of exercise is most effective at preventing or managing a specific illness, nor does it suggest that the dose/response curve is linear (ie how much exercise of a given type would optimize health, vs diminishing health with excessive exercise). I'm trying to make the argument that high intensity exercise seems to be the most practical course for a sedentary person looking to improve their health with minimal risk.

I'm not dismissing the importance of HDL, LDL, or Triglyceride levels, just pointing out that it's severely oversimplified and not well understood. In particular factors such as mean LDL residence time, particle size, and lipid composition are much greater predictors of cardiovascular risk than total LDL, but are not yet commonly tested for. High LDL could be a risk factor at the population level only because high LDL tends to have a certain cause or follow a particular pattern in that population. In particular, it's surprising that high saturated fat consumption raises LDL significantly yet fails to correlate with increased cardiovascular deaths even in the extreme when it makes up the majority of total calories ( http://pmid.us/20071648 and http://pmid.us/16018792 among many others).

There is a lot of new evidence that nearly all autoimmune inflammatory diseases co-occur with "leaky gut" or decreased intestinal permeability, plus gut dysbiosis (unusual patterns of gut microbial species). Exactly what this says about how we should be treating those illnesses is unclear.

High intensity exercise *also* maximally taxes the cardiovascular system and produces the same or better aerobic capacity improvements as endurance training with less training time (http://pmid.us/8897392). If you notice AFTER high intensity exercise, you're out of breath for a very long time. During this period your cardiovascular system continues to work at maximum capacity for quite some time, breaking down leftover lactic acid from your short period of high intensity exercise. The HDL/LDL/TG measure in terms of "good/bad/bad" is oversimplified to the point of meaninglessness but basically if excess glucose is getting shunted into muscle tissue, then it's not undergoing denovo lipogenesis and raising triglycerides and small dense LDL. Arthritis is primarily an autoimmune inflammatory disorder, and for that I think dietary changes may be more effective than any exercise regimen.... especially dietary omega 3/6 ratio (reduce high linoleic acid seed oils, eat more fish) and testing for unidentified common food allergies through systematic elimination and reintroduction (gluten, casein, etc.). The biggest thing that bothers me about intense regular aerobics/endurance training is the hormonal stress response (significantly elevated cortisol that stays raised for weeks after training ceases). In the long term high cortisol levels totally wreck your health in many different ways. However this is much more of an issue for pro-athletes than someone doing just a few hours a week of aerobics.

If it's not high enough intensity, than only a small portion of muscle fibers (slow twitch) are engaged, so you don't drain as much glycogen from your muscles or make the same beneficial metabolic adaptations. If its *too high* intensity (such as a single powerlift) the slow twitch muscle fibers never fatigue fully. Reaching total muscle failure in about a minute or so through weight lifting can engage and fatigue nearly all of the muscle fibers in the group being worked, so it gives you the most "bang for your buck" in terms of metabolic adaptation with a limited training time. There's many peer reviewed studies supporting this, such as this one (http://www.biomedcentral.com/1472-6823/9/3/abstract).

The book I quoted in my previous post ("Body by Science") makes a very strong argument that about 8 minutes/week of very high intensity exercise (weight training to failure) is at least as good as, if not superior to other more time consuming exercise regimens. The authors draw from a rational argument based on physiology and biochemistry, decades of research supporting this viewpoint, and decades of anecdotal success using these techniques themselves. As a programmer/grad student whom must work long hours at a desk, this is my only practical option anyway. Myself, I saw radical changes in my body composition and insulin sensitivity within a few months... nothing like that ever happened with my previous attempts at regular running, cycling, jogging, etc.

I strongly question the notion that burning calories or raising your heart rate are (independently) where the benefits of exercise come from. Numerous studies show that short duration high intensity exercise (such as Tabata Intervals, or the weight training methods in "Body by Science") produce the same or greater metabolic adaptations (VO2 max, strength, weight loss) with significantly less time spent, and significantly less calories burned. Health improvements from exercise come mostly from activating a specific biological response/adaptation by applying a specific type of stress to your body, not from altering your energy homeostasis by burning calories. Running is probably one of the worst forms of exercise for improving health, since it causes long term joint/leg problems, and tends to cause muscle wasting as your body consumes muscle to maintain glucose levels... but the exercise doesn't use muscles in a way that induces a hypertrophic response.

This is an epidemiological study, so it cannot establish cause and effect. It's highly plausible that people whom live longer also exercise more, because of other factors (such as being physically able to). There's also many different types of exercise with totally different metabolic effects, which this study doesn't isolate. Moreover, it's only capable of looking at the range of activity present in the population it's looking at (relatively sedentary people in Taiwan). Personally, I think if you're going to do exercise for the explicit purpose of improving health and extending life, you shouldn't focus on replicating the amount of time spent exercising by the longest lived people in this group. There's a lot more information you can learn from also (biochemical understanding, exercise physiology studies, other epidemiological studies of other populations, etc.) I suspect spending less time doing high intensity exercise (such as the 8 minutes/week of heavy weight lifting to total failure as explained and justified biochemically in great detail in the great book "Body by Science") is much more likely to extend life span, and prevent metabolic syndrome (the main cause of death in developed countries) with much less time commitment. Not to mention that it will make you ****ing ripped with significant measurable weekly increases in strength that continue for a year or two. High intensity exercise (like weight lifting or sprinting) can use up most of your glycogen reserves quickly, and with little chance of injury in a way that almost no other exercise can. This improves insulin sensitivity (one of the main problems of metabolic syndrome) significantly for weeks after the exercise.

I'm not sure... but here's a few guesses: 1) The bacteria grow on other substrates (dirt, grass, etc.) trapped in the wool 2) The wool is simply more resistant to bacteria growth such that no significant growth occurs in a single day or a few days between clothes washings. 3) Are you sure sheep smell? I'm not sheep farmer, but I have visited them and they certainly aren't as smelly as most other livestock. The important thing isn't understanding the underlying mechanism... but the reality that wool clothes are much more resistant to odor than essentially any other type of fabric. If people are concerned about this issue, or having problems with it, why not use wool? I have no financial interest here, but I personally own almost entirely wool clothes... they're just more durable, less smelly, and more comfortable (in the case of high grade/fine diameter wool) than anything else I've worn.

Wool does this naturally.... it's microscopic physical structure is such that bacteria has a difficult time attaching to it physically. When I switched to wool socks I permanently eliminated smelly feet, and they're much more comfortable even in hot weather. Once again, scientists develop a "novel" solution to a problem nature solved much more elegantly long ago. Wool literally evolved for the explicit purpose in which humans use clothing for: keeping mammals comfortable and healthy in a wide range of climates... and it has a complicated structure that gives it unique properties to this end that have yet to be replicated by synthetics.

Moreover, studies like this often involve diet questionnaires that test a large number of different hypotheses at the same time. If you test enough hypotheses with the same exact experiment you can practically guarantee that you'll find some statistically significant (and therefore publishable) correlations in your data due to random error, even if no causative relationships actually exist.

This headline is grossly misleading, this isn't what the study says at all. Correlation does not imply causation! This is an "epidemiological study" meaning it looks for statistically significant correlations between different factors (such as coffee and prostate cancer). In many (probably most) cases these correlations are either due to an external factor not considered, or are just a random statistical artifact (the phrase statistically significant is actually relatively meaningless, and about one out of 20 hypotheses will prove statistically significant in epidemiological studies due to random chance). What if coffee drinkers get less cancer because they're more likely to drink coffee instead of another beverage directly causing the cancer? What if these people are drinking more coffee because they have a hormonal problem that reduces energy levels, but also happens to lower cancer risk? I can go on forever here with plausible alternate explanations, but my point is that this observed correlation doesn't imply that drinking more coffee will prevent prostate cancer! When will science journalists and the general public learn that epidemiology only generates hypotheses, but doesn't test them? Every time I see an epidemiological correlation in the news it's presented as conclusive evidence that you should do x, and then a week later there's another study saying you should do the exact opposite for a different reason! My takeaway conclusion from nearly all news headlines saying x is good or bad for you is that we need to do a better job teaching people about statistics, experimental design, and critical scientific thinking in school.

Instead of "are" I should say tend to be... I've met several women whom were stronger than most men.

While you're correct that men are stronger than women, "intelligence/perception of surroundings that is beyond that of the female" is a sexist claim with no scientific basis.

The fact that males still exist despite the existence of hermaphrodites shows that they are essential. Sexual reproduction allows for recombination and greater diversity, increasing the ability of the species to adapt to new environments, diseases, or stressors and to eliminate deleterious mutations. Gradual accumulation of deleterious mutations (called "muller's ratchet") often causes species that lack the ability to reproduce sexually (even just occasionally) to go extinct.