Why do dogs tilt their heads when curious / confused? |
- Why do dogs tilt their heads when curious / confused?
- Can the speed of light be theoretically calculated using quantum mechanics?
- How do we know the age of the universe?
- Are there any animals that don’t fit easily into a group (mammals, birds, etc)?
- How does luminosity scale with human perception of brightness?
- Do we know exactly what the atmosphere was composed of when cyanobacteria producing oxygen 2.7-2.8bya?
- What is the minimum velocity an electron needs to escape through a vacuum after entering the conduction band of the metal electrode?
- Why does fish decay faster (and smellier) than meat?
- Have any species followed an evolutionary path like cetaceans, only to revert to land-dwelling?
| Why do dogs tilt their heads when curious / confused? Posted: 24 Dec 2018 09:27 PM PST |
| Can the speed of light be theoretically calculated using quantum mechanics? Posted: 24 Dec 2018 08:43 PM PST I know the speed of light can be accurately predicted from Maxwell's equations, is there a mathematical way to arrive at the speed of light another way? Can you do it using quantum mechanics? [link] [comments]  |
| How do we know the age of the universe? Posted: 24 Dec 2018 09:01 PM PST And due to time dilation, does that mean that some parts of the universe are "younger" than others? [link] [comments]  |
| Are there any animals that don’t fit easily into a group (mammals, birds, etc)? Posted: 24 Dec 2018 07:30 PM PST Like a mammal that lays eggs or a bird that's cold blooded? Obviously that's pretty extreme. But are there any animals whose group is debated? I find it kinda of amazing that in the process of evolution and natural selection, these groups would be so distinct and animals fit so well in them. [link] [comments]  |
| How does luminosity scale with human perception of brightness? Posted: 24 Dec 2018 10:17 PM PST Bear with me; I'm struggling with the terms involved. I can find some information on this question concerning the use of apparent magnitude in astronomy. But I'm having a hard time comparing apparent (and absolute) magnitudes with SI units for luminosity and such. Say I step into a closed room with a single light source that's a fixed distance from my eye. The light initially appears at the brightness of a "typical" candle. (So that would be one candela? which is 12.57 lumens?) I turn down the brightness until the light is JUST at my limit of perception. How many lumens is it now? I guess we need to define a distance between the candle and the eye, so let's say 1 meter? I guess the alternative approach here would be to keep the brightness (luminance?) constant and move the candle further away until I can't quite see it. I found an article saying this distance is something like 2.5 km, but I didn't quite follow how they got there and I can't piece together how that relates to the "decrease the brightness" approach. Ultimately it's about the number of photons hitting your eye, so distance means less flux. I get that much very well. There's just some link in the chain that I'm getting lost here as I've never worked with these units much. (And yes, I'm specifically interested in a human eye. I'm aware that these units "filter" light wavelengths so they are weighted based on human perception.) [link] [comments]  |
| Posted: 24 Dec 2018 08:58 PM PST |
| Posted: 24 Dec 2018 12:05 PM PST |
| Why does fish decay faster (and smellier) than meat? Posted: 24 Dec 2018 01:06 AM PST It looks like fish ---and i don't mean just zoological Fish, but seafood, sea dwellers in general, including mollusks, shrimps, urchins etc--- rots a lot sooner than land animals flesh. It is as if the bacteria responsible of the decay in the dry find, in anything that has grown in water, their absolute favourite food. Is there a reason for this? [link] [comments]  |
| Have any species followed an evolutionary path like cetaceans, only to revert to land-dwelling? Posted: 23 Dec 2018 11:00 PM PST |
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