Can you use a magnifying glass and moonlight to light a fire? (2016)

jstanley wrote: post #4

detaro wrote: post #3

EDIT: I'm not sure about this anymore.

I think TFA refutes your argument, but I'm not smart enough to know for sure. Can you please expand on this?

What if the sun was a bunch of parallel laser beams? Then you could focus them all into a single point.

Re: Can you use a magnifying glass and moonlight to light a fire? (2016)

#8

Post by detaro » Fri, Dec 21, 2018, 9:57 PM UTC

jstanley wrote: post #4

detaro wrote: post #3

EDIT: I'm not sure about this anymore.

I think TFA refutes your argument, but I'm not smart enough to know for sure. Can you please expand on this?

On second look, the thing I thought of doesn't work, so I retract the statement...

Re: Can you use a magnifying glass and moonlight to light a fire? (2016)

#9

Post by jstanley » Fri, Dec 21, 2018, 9:59 PM UTC

randyrand wrote: post #7

jstanley wrote: post #4

Earlier quoted context omitted.

I think TFA refutes your argument, but I'm not smart enough to know for sure. Can you please expand on this?

What if the sun was a bunch of parallel laser beams? Then you could focus them all into a single point.

Right, but that point would be exactly as hot as the surface that the light was coming from, and no hotter.

(Is the argument as I understand it).

Re: Can you use a magnifying glass and moonlight to light a fire? (2016)

#10

Post by ohiovr » Fri, Dec 21, 2018, 10:07 PM UTC

I had the presumption that you could make a mega hot spot with a large enough lens back in the 90s. Fortunately usenet set me straight. It was a long and facinating journey to understand all the whys about it.