Hacker News Reader

Comment by nathan_long | Hacker News Reader

Given that visible light and radio waves are the same thing except that visible frequency, my first thought was "why don't they focus the radio waves rather than switching to visible light?"

I suppose that higher frequency waves can encode more information, but I'd guess they also have a harder time penetrating the atmosphere. Maybe we don't have a mechanism for producing "radio laser?"

Can anybody clarify for me?

View on HN

Yes, actually the "radio laser" (actually, microwave laser [1]) was the first type of *aser invented!

The reason they haven't been proposed for deep-space communication is that thus far, unlike lasers, they have required bulky cooling mechanisms and solid-state semiconductor masers have not been possible. The future does look brighter due to a recent breakthough, though [2].

[1] http://en.wikipedia.org/wiki/Maser

[2] http://www.nature.com/news/microwave-laser-fulfills-60-years...

I'm expecting, one day, for half the moon to be covered in antenna gear and us using it as one large phased array software-defined radio. Like arecibo observatory, but HUGE.

That may be closer than your think (except for the moon bit, space is hard). See LOFAR: http://www.lofar.org/about-lofar/about-lofar "LOFAR is the first telescope of this new sort, using an array of simple omni-directional antennas instead of mechanical signal processing with a dish antenna. The electronic signals from the antennas are digitised, transported to a central digital processor, and combined in software to emulate a conventional antenna. "

There are quite a few sensor networks out there at the moment:

PressureNet: Android barometer sensors ADS-B for flight data AIS for ship traffic CORS for precise GPS positioning data

It would not be out of the realm of possibility to have ~$500 software defined radios across the world with network connections, all funneling back to a data processing facility.

Awesome!

We have MASERs, but they just aren't usefull for that. Because theyr wave-length is bigger, a "radio laser" difuses into a huge area before getting into Earth.

Higher frequency radiation tends to give you a more focused beam for a given lens size. Here's a run related tool for figuring out how much damage a laser beam will do given frequency, energy, lens size, etc.

http://www.5596.org/cgi-bin/laser.php

Reply on news.ycombinator.com