Researchers Create Gold Aluminum, Black Platinum, Blue Silver • Hacker News Board

Re: Researchers Create Gold Aluminum, Black Platinum, Blue Silver

#41

Post by ars » Tue, Dec 29, 2009, 7:24 PM UTC

DLWormwood wrote: post #38

ars wrote: post #29

Earlier quoted context omitted.

Not sure what an imperfect one-way mirror is. Do you mean, something that is mostly one way? Because, no, you can't. And you can't make an active one-way mirror either (at least not without inputting energy) - see http://en.wikipedia.org/wiki/Maxwells_demon

You've never seen a security mirror ( http://www.howstuffworks.com/question421.htm ) before? They're what the parent posters are refering to...

I was waiting for someone to mention those.

They are not one way. Not in the slightest.

You can turn them around, and they will work unchanged.

They transmit exactly the same amount in both directions.

The only reason they seem to work is that one room is well lit, and the other is dark. So it's hard to see anything from the well lit room.

They are half silvered, so they reflect half, and transmit half. The well lit room then reflects lots of light, but is receiving little light from the dark room.

The dark room reflects little light, but is getting lots from the well lit room.

Re: Researchers Create Gold Aluminum, Black Platinum, Blue Silver

#42

Post by DLWormwood » Wed, Dec 30, 2009, 5:34 AM UTC

ars wrote: post #41

DLWormwood wrote: post #38

Earlier quoted context omitted.

You've never seen a security mirror ( http://www.howstuffworks.com/question421.htm ) before? They're what the parent posters are refering to...

I was waiting for someone to mention those. They are not one way. Not in the slightest. You can turn them around, and they will work unchanged. They transmit exactly the same amount in both directions. The only reason they seem to work is that one room is well lit, and the other is dark. So it's hard to see anything from the well lit room. They are half silvered, so they reflect half, and transmit half. The well lit…

> They are not one way. Not in the slightest.

Hence the references to "imperfect" a few messages back. Pedantry of the kind you're exposing is dangerous (even life threatening) in real life.

Re: Researchers Create Gold Aluminum, Black Platinum, Blue Silver

#43

Post by ars » Thu, Dec 31, 2009, 4:14 PM UTC

DLWormwood wrote: post #42

ars wrote: post #41

Earlier quoted context omitted.

I was waiting for someone to mention those. They are not one way. Not in the slightest. You can turn them around, and they will work unchanged. They transmit exactly the same amount in both directions. The only reason they seem to work is that one room is well lit, and the other is dark. So it's hard to see anything from the well lit room. They are half silvered, so they reflect half, and transmit half. The well lit…

> They are not one way. Not in the slightest. Hence the references to "imperfect" a few messages back. Pedantry of the kind you're exposing is dangerous (even life threatening) in real life.

But it's not "imperfect". It's 0. It's not one way in the slightest.

If I turn the lights off in my house and you can't see me through an open window will you tell me the open window is a one way window?

Imperfect implies say, 49% of light goes one way and 51% goes the other. Such a mirror does not exist.

And please remember the context (although I think the poster was embarrassed and deleted his original comment), we are talking about making black colors on metal, and he was wondering if it's because it's a one way mirror.

Re: Researchers Create Gold Aluminum, Black Platinum, Blue Silver

#44

Post by eru » Thu, Dec 31, 2009, 6:39 PM UTC

ars wrote: post #29

eru wrote: post #25

Earlier quoted context omitted.

Of course you can make imperfect or active one-way mirrors.

Not sure what an imperfect one-way mirror is. Do you mean, something that is mostly one way? Because, no, you can't. And you can't make an active one-way mirror either (at least not without inputting energy) - see http://en.wikipedia.org/wiki/Maxwells_demon

You are right about context and thermo-dynamics and all.

With active one-way mirror I meant one where you have to input energy.

Re: Researchers Create Gold Aluminum, Black Platinum, Blue Silver

#45

Post by JoeAltmaier » Mon, Jan 04, 2010, 7:41 PM UTC

ajross wrote: post #39

jacquesm wrote: post #37

Earlier quoted context omitted.

It could for instance be more durable because it doesn't fade due to ultra-violet light breaking down the pigment.

The same is true of ionic pigments, though. Only the organics fade in sunlight. Again, hardly an earth-shattering innovation. Might make it useful in toys where toxic pigments can't be used...

How about a micro-coating. Not applied like paint, deposited on the surface like an integrated circuit layer, microns thick. SUre you can still call it paint, you can call the layers of an integrated circuit paint but its deposited differently, is a differnt industrial process, mechanically different, different thermal characteristics, lots of things. More significant in my original comment was this: the color can be "dialed", kind of like "digital color". Paint is imperfectly mixed material with wide color/reflectivity variation over a surface. This new method of coloring a surface is uniform. Imagine the efficiency of a color filter, absorbtive surface, radiative surface etc if the optical properties could be tightly controlled over a wide area.