Comment Re:The sky is falling! (Score 1) 121
First space balls, now this?!
A titanium ball of about five kg fell on to the roof of a house in Ordyn district.
No, no, this is still space balls.
First space balls, now this?!
A titanium ball of about five kg fell on to the roof of a house in Ordyn district.
No, no, this is still space balls.
My 6 year old daughter tests as having an extreme allergy to peanuts. As per doctors orders she hasn't been exposed to peanuts and always has an injector for emergencies (which is a real pain at school since they have a no-drugs policy that won't even let them have emergency medicines).
Zero tolerance policies have officially gone too far.
She loves everything fluffy, but prefers dogs over cats.
Good girl, cats are evil.
So to your first post, the claim is not that you cannot collect all the light nor that you are in fact able to focus it to exactly the intensity of the source. In your system the translucent sphere serves to prevent us from focusing the light anywhere near the intensity of the original source, so there is nothing wrong with that. Further, we would now find ourselves unable to focus the light to a spot any more intense than the surface intensity of the translucent sphere. If one were to envelop the whole system with collectors one could in principle collect all the light, just not at one spot.
If the collectors are all mirrors then I don't see why you couldn't. Admittedly, you can't possibly have a perfect reflector, but there's no reason you couldn't focus all the gathered energy on a single point. If there were a laws-of-thermodynamics reason for that to be impossible than you could never power a laser which has a focal point hotter than the surface of the sun with solar panels. But you can. Yes, that makes a conversion from light to electricity and back, but you lose energy doing so. Therefore it must be possible (within the laws of physics, if not current tech) to focus sunlight down to the same intensity with mirrors.
To your 2nd post, "the system" must include the energy radiated away. The energy is not decreasing, but the entropy is. For a thought experiment, assume you are able to focus the light as tightly as you wish, and heat an object to greater than the source's temperature. You could then connect the two objects together and heat would flow from the hotter one to the cooler because that is what maximizes the entropy. Therefore we had violated the 2nd law when we heated the object above the source's temperature.
would heat flow from the hotter to the colder? Yes. However, it will also radiate outwards from the hotter object in every other direction too. The total entropy is still increasing, it's just doing it more slowly. Congradulations, you just discovered insulation. Homebuilders everywhere thank you.
Your setup with the elliptical reflector would not work. Because the sun has finite size, you would find that at the other focus the light isn't directed to a single point, but at a sphere the same size as the sun. In this most extreme possible scenario, you could heat an object there to exactly the sun's temperature, but no higher. Within that sphere the light is not traveling radially inward to the focus, rather most of the light is missing the focus because it was emitted from the sun's surface, not its center.
Ok, the elliptical reflector only matches the surface temperature. I'd still like to see the proof that something that works better is impossible. You have a link to something with the math? A thought... If I focus a reflector (arbitrarily size) at a point epsilon above the surface of the sun, haven't I just harnessed radiation from the sun to cause a point (not on the surface) to be hotter than it's surface?
Anyone can make an omelet with eggs. The trick is to make one with none.
