Thursday, August 06, 2015

Creating a Germanium Flare

This post is a follow-up to the one at http://newstudentresearch.blogspot.com/2015/08/looking-at-universe-using-germanium.html that had argued that emission spectral lines of heavy elements are especially attractive for interstellar signalling.

Let us consider further the experiment of sending a few tons of a heavy element such as germanium to fall into the solar atmosphere; I use the term “heavy element” to refer to elements that are not synthesized in stars. We would not need to use high purity Germanium, even 90% purity may be sufficient for this purpose. We would need to study the dynamics of the inserted material in the chromosphere. How much energy will it release in specific spectral bands as narrow as individual spectral lines? What would be the time constants of the energy release? What will be the signal to noise ratio that a remote observer would have to work with, to detect the event? What will be the extent of broadening of the spectral lines due to the temperature in the chromosphere?  These are interesting scientific questions.

Then there is the usual SF question: would we be sending out with a germanium flare a signal that we exist, and possibly attract a violent reaction from some advanced civilization? An option would be to send a smaller package of Germanium to fall into the Sun’s atmosphere – big enough to give us answers to our scientific questions and yet too small to be noticed at interstellar distances. A small package would also be more affordable; a ton of germanium probably would probably cost a million dollars or more!

A possibility that terrifies me is that no other civilization exists that we could communicate with; and, that we are all alone.

Tuesday, August 04, 2015

Looking at the universe using Germanium based photodetectors

I would like to sound out readers of this post about some speculative ideas. The assumption is that advanced civilizations might have discovered that the abundance of elements such as Germanium in stellar atmospheres is pretty close to zero. They could have also discovered that one could build Germanium based photon detectors and Ge based lasers. This opens up the possibility of interstellar signalling using photons produced by Ge based Lasers. An alternative method of sending a strong signal would involve sending spacecraft made of Germanium to fall into the atmosphere of a nearby star in a controlled time sequence. Each spacecraft falling into the stellar atmosphere ought to produce several megawatts of radiation from Germanium heated to very high temperatures. 

The weak element in the communication chain would be the Germanium based photo-detectors put together by another civilization, presumably scanning for these signals at some far away location; their spectral selectivity would not be adequate to reject extraneous light. While they will optimally detect photons with the right energies, they will also detect photons with other energies. The question that arises is if there is a way to design detectors that will be highly selective to radiation produced by excited Ge atoms only. A way to do this might be to use silicon doped only with Ge and operating at a voltage where Ge originated photons would create a cascade, while other photons will not. If we can create such a detector, we can get amazing signal-to-noise ratios for the whole system. Ideally, we would need an array of detectors so that we can scan an area of the sky using parallel detection elements.

I would like to add a couple of more thoughts. The universe creates little light at the wavelengths we have talked about except perhaps in some supernovae. Secondly, red shift may not be insurmountable problem, because we hope to look for signals arising within a few hundred light years from the earth. The red shift involved may be small enough to be handled in some way.  
Please do share your thoughts. I do moderate comments to avoid advertisements and such, but shall be happy to publish comments even if they say why this method of interstellar signalling will not work.
 
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