Royal Astronomer: 'Aliens may be staring us in the face'

[RJN]

http://www.telegraph.co.uk/science/spac ... -face.html
Copyright: Telegraph

Lord Martin Rees, president of the Royal Society and astronomer to the Queen, said the existence of extra terrestrial life may be beyond human understanding.

[neufer]

http://www.telegraph.co.uk/science/spac ... -face.html
Copyright: Telegraph

Lord Martin Rees, president of the Royal Society and astronomer to the Queen,
said the existence of extra terrestrial life may be beyond human understanding.

• E.g.:

http://asterisk.apod.com/viewtopic.php? ... 9&p=116292
http://asterisk.apod.com/viewtopic.php? ... 3&p=116239

[makc]

I suspect that Lord Martin Rees, as old as he is, simply looks for acceptle way to let The Lord into his life.

[BMAONE23]

Funny that we are "surrounded by a 50 light year-wide "shell" of radiation from analogue TV, radio and radar transmissions." given that these transmissions travel at the Speed of Light and the 1936 Olympics were televised the Television related broadcast shell should be 74 lightyears wide (radius) or 148 lightyear diameter (wide). The Radio wave shell would be even wider at 104 LY Radius or 208 LY Diameter.
I think the Royal Astronomer or the Telegraph Reporter needs a little more math skills

[neufer]

Funny that we are "surrounded by a 50 light year-wide "shell" of radiation from analogue TV, radio and radar transmissions." given that these transmissions travel at the Speed of Light and the 1936 Olympics were televised the Television related broadcast shell should be 74 lightyears wide (radius) or 148 lightyear diameter (wide). The Radio wave shell would be even wider at 104 LY Radius or 208 LY Diameter.
I think the Royal Astronomer or the Telegraph Reporter needs a little more math skills

I doubt if any sufficiently strong VHF (>30MHZ) radiation leaked out of earth's
ionosphere prior to the advent of multi-kilowatt magnetrons during WWII:

<<The first simple, two-pole magnetron was developed in 1920 by Albert Hull at General Electric's Research Laboratories (Schenectady, New York), as an outgrowth of his work on the magnetic control of vacuum tubes in an attempt to work around the patents held by Lee De Forest on electrostatic control. Throughout the 1920s, Hull and other researchers around the world worked to develop the magnetron. However, the two-pole magnetron, also known as a split-anode magnetron, had relatively low efficiency. The cavity version (properly referred to as a resonant-cavity magnetron) proved to be far more useful.



While radar was being developed during World War II, there arose an urgent need for a high-power microwave generator that worked at shorter wavelengths (around 10 cm (3 GHz)) rather than the 150 cm (200 MHz) that was available from tube-based generators of the time. A multi-cavity resonant magnetron had been developed and patented in 1935 by Hans Hollmann in Berlin. However, the German military considered its frequency drift to be undesirable and based their radar systems on the klystron instead. But klystrons could not achieve the high power output that magnetrons eventually reached. This was one reason that German night fighter radars were not a match for their British counterparts.


[list]Klystron[/list]
In 1940, at the University of Birmingham in the United Kingdom, John Randall and Harry Boot produced a working prototype similar to Hollman's cavity magnetron, but added liquid cooling and a stronger cavity. Randall and Boot soon managed to increase its power output 100 fold. Instead of abandoning the magnetron due to its frequency instability, they sampled the output signal and synchronized their receiver to whatever frequency was actually being generated. In 1941, the problem of frequency instability was solved by coupling alternate cavities within the magnetron.

Because France had just fallen to the Nazis and Britain had no money to develop the magnetron on a massive scale, Churchill agreed that Sir Henry Tizard should offer the magnetron to the Americans in exchange for their financial and industrial help (the Tizard Mission). An early 6 kW version, built in England was given to the US government in September 1940. At the time the most powerful equivalent microwave producer available in the US (a klystron) had a power of only ten watts. The cavity magnetron was widely used during World War II in microwave radar equipment and is often credited with giving Allied radar a considerable performance advantage over German and Japanese radars, thus directly influencing the outcome of the war. It was later described as "the most valuable cargo ever brought to our shores". (Klystron tube technologies for very high-power applications, such as synchrotrons and radar systems, have since been developed.)

The Bell Telephone Laboratories made a producible version from the magnetron delivered to America by the Tizard Mission, and before the end of 1940, the Radiation Laboratory had been set up on the campus of the Massachusetts Institute of Technology to develop various types of radar using the magnetron. By early 1941, portable centimetric airborne radars were being tested in American and British planes. In late 1941, the Telecommunications Research Establishment in Great Britain used the magnetron to develop a revolutionary airborne, ground-mapping radar codenamed H2S.

http://www.planetary.org/blog/article/00002356/

Centimetric radar, made possible by the cavity magnetron, allowed for the detection of much smaller objects and the use of much smaller antennas. Maritime patrol aircraft to detect objects as small as a submarine periscope, which allowed aircraft to attack and destroy submerged submarines. Centimetric gun-laying radars were likewise far more accurate than the older technology. They made the big-gunned Allied battleships more deadly and, along with the newly developed proximity fuse, made anti-aircraft guns much more dangerous to attacking aircraft. The two coupled together and used by anti-aircraft batteries, placed along the flight path of German V-1 flying bombs on their way to London, are credited with destroying many of the flying bombs before they reached their target.

Since then, many millions of cavity magnetrons have been manufactured; while some have been for radar the vast majority have been for microwave ovens. The use in radar itself has dwindled to some extent, as more accurate signals have generally been needed and developers have moved to klystron and traveling-wave tube systems for these needs.>>