1. ## Janus

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2. ## CharonY

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3. ## Strange

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4. ## Ken Fabian

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## Popular Content

Showing content with the highest reputation on 01/02/18 in all areas

1. 2 points

## 3 events that happened only once in history

Also, ribozymes are clearly not the ancestor of eurkayotic life but fall into the category of the RNA world hypothesis, which is far from an established fact. More specifically though, how do you define "only once"? There are obviously plenty of ribozymes and their early origins are still unclear. Also chromosome re-arrangement has been observed in many species and is clearly not an unique event either. Forgot to add, endosymbiotic events related to formation of eukaryotes also happened more than once. Mitochondria likely originated from aerobic bacteria, whereas plastids likely evolved from cyanobacteria.
2. 1 point

## Time and speed and how speed impacts time

I'm going to try an analogy here to try and get the idea across. Imagine you have two men. They start at the same spot and start walking in different directions. After they both have walked an equal distance, on man turns so that his new path will cross the other man's path. After both have walked an equal distance again, they come to a stop and measure how far they are from where they started. The man who changed direction during his walk will find himself on the other man's path line, but closer to where he started than the the man who didn't change direction. Now it doesn't matter how they measured the distance they walked, they could have used a tape measure (equivalent of measuring time with a clock) or counted the number of steps they took of equal stride length (equivalent of biological aging or personal perception of time passage), They still end up with one man closer to where they started than the other. The same is true for accumulated time difference due to Relativity. It doesn't matter how you measure "time", by a clock or human "age", less time will have passed for one person than for the other. You simply cannot separate "aging" from time measured by a clock. They are both the result, on a fundamental basis, of the same thing.
3. 1 point

## Polyurethane foam - are they safe?

I worked on PU foam R&D for 8 years so I know a bit about it. Isocyanate is highly reactive and is all consumed in the manufacturing process. Such foams are widely used in cot mattresses and institutional bedding. The combination of mattress cover and condition is highly significent in safety terms. I wouldn't buy a secondhand one in any case. Modern formulations are safe although there have been questions related to cot death and I would not advise using a secondhand one for babies, especially very young ones. There was also govt. advice to lie babies on their backs. Again, I wouldn't buy a secondhand one. There were also concerns about the extreme flammability of early formulations and much development focussed on dealing with this problem and you would be advised to check flammability ratings on any products you have. Latex foams do not suffer from the same potential disadvantages but again should be checked via manufacturers advice.
4. 1 point

5. 1 point

## Vertical Farms: Ethanol Fuel

I'm not sure vertical ethanol farming would manage 3 acres per floor. Maximising the area exposed to sunlight would mean limiting the area to that which allows sunlight to penetrate. Where vertical farming makes effective use of sunlight it makes equivalent large areas that are shadowed; you can't pack them too closely or they shade each other. Light will penetrate mostly from the sides rather than above; no light coming from above will reach the floor below the top one. Ultimately no more sunlight is available than with horizontal farming. Replacing sunlight with artificial lighting would introduce a major energy input in a process intended to maximise energy output - and even if the lighting is high efficiency, plant conversion of light to energy is not - more than 2% of the sunlight converted is considered very good. That may be improvable by selection, breeding and genetic engineering - but enough? Artificial lighting is not so good; it has to use sunlight as it's principle energy source to deliver more energy than it consumes. The innate usefulness of biofuels has been based on the fact that ones like wood just grow, often on agriculturally marginal land, without cultivation and with minimal processing. I suspect the much higher efficiency of Photovoltaics combined with electrically driven chemistry has greater potential to produce transportable liquid (or gas) fuels. How well they can compete with (still improving) batteries will probably be revealed over the next decade or two.
6. 1 point

## Mass in black holes (split from Mass)

Yes you are. And, as usual when you make stuff up, you are wrong. But that doesn't include mass. https://en.m.wikipedia.org/wiki/Information_theory
7. -1 points

## Time and speed and how speed impacts time

OK, finally I can reply again (I was stymied by being a first day member there for a while). So a clock slows when it moves fast, that's been proven evidently. But I don't see how the behavior of a clock necessarily relates to aging. So StringJunky, a clock goes through time the same as an aging person or an opening flower and because the clock shows a different process at fast speeds then the assumption is that a person aging, or a flower opening, would experience changes in their processes that would coordinate with the changes in the clock? I don't get how you make that jump? Where's the logical leap from rate of clock change to rate of aging or rate of flower opening? Can we not age, or can flowers not bloom, independent of the clock rate? Outrider you told me "Time is what clocks measure. A clock can be anything that has a rate of change, so an aging person can be a clock." I don't get that. An aging person, scientifically speaking, is different from a clock. A clock is a fairly precise measuring device, the aging person is not. As I said above, why does the behavior of the clock at high speeds tell you anything about how a person ages relative to that clock's changes at high speed? That's the part that makes little, or no, sense to me. Plainly, I don't get why people have conjured that aging happens by clock rate. People age by time, not clock rate. So, just because a clock rate changes at speed, I don't see how that has to do with time in regards to aging or blooming.
8. -1 points

## Time and speed and how speed impacts time

Obviously. But you knew that was an "egging on" question, right? Time is personal, not mechanical. Agreed. The mechanism of time is an invention, not a given part of the universe. Time was never given to us, we created it.
9. -1 points

## Time and speed and how speed impacts time

Thank you. That means a lot to me actually that I'm not completely crazy! But I guess physics is kinda wrong when they try and describe time in regards to age.
10. -1 points

## Time and speed and how speed impacts time

The important point here is that time dilation is not an effect on the clock. It can't be. For example, right now you are traveling at 0 km/h relative to your chair (no time dilation) you are also travelling at hundreds of miles per hour relative to Mars (a bit of time dilation) you are also travelling at 99% of the speed of light relative to cosmic rays (a lot of time dilation). Your clock can't be running at multiple different speeds, affected by every relative velocity. OK, that's all fine, but does it have to do with human age?