Subject: I have found a DVD that I think you would enjoy
|NOVA Death Star|
Actor: Stacy Keach
Director: David McNab
They are so bright, they are a billion billion times more luminous than the sun. They are so distant, their light takes billions of years just to reach Earth. These amazingly violent explosions-or death stars-may even have... more »
One of the most facinating science documentaries I have seen
Karl C. Nelson | San Antonio, TX USA | 10/26/2006
(4 out of 5 stars)
"While I missed the original NOVA broadcast, I have been able to catch this episode numerous times on the Discovery SCIENCE channel. One of the things that makes this program so interesting was that these distant bursts were so powerful, that Einstein's law E=mc^2 might have been violated. This phenomonoe was threatening to unravel the entire world of physics as known ! How this issue gets resolved, saving Einstein (and not a few professional reputations in the process) opens new avenues to investigation into other unknown realms of the distant Universe. For the viewer who has a casual interest in cosmology, sans all the complex mathematics (I was never good in math) then this program is one for you !"
Very informative, but on the boring side
Quinten Pullen | US Navy, everywhere | 05/30/2007
(4 out of 5 stars)
"This video was informative, the topic really interesting. But their presentation is on the boring side. I wish I could find the BBC video of the same name, it covered the same topic but was quite a bit less boring."
Very educating and entertaining
Rasih Bensan | Istanbul, Turkey | 04/06/2009
(5 out of 5 stars)
"As usual this documentary by Nova is very interesting, well explained, educating and nice to watch due to very high quality images and there are interviews with the scientists conducting the research.
The first part of this documentary film explains the research to find the origin of gamma rays coming to our planet from space. The second part is about the hunt for supernovae.
In the first part it is explained that in 1967 the USA put a satellite in Earth's orbit to detect any secret nuclear explosion tests the Soviets maybe making in space. The satellite was to detect any gamma rays emitted from such tests. Gamma rays are the shortest wavelength form of radiant energy discovered so far and are generated by nuclear explosions during which matter is converted into energy. The satellite was bombarded with gamma ray emissions from all directions from deep space. It became immediately evident that this could not be caused by secret Soviet nuclear testing in space. This started research by scientists around the world to find out what the nature of all these gamma ray burst sources in space were. The research revealed that the sources were far beyond our galaxy, because they were scattered randomly throughout the whole sky. Had they been in our galaxy they would have been concentrated around the milkyway part of our sky.
At first, neutron stars formed by supernovae ( exploding stars ) were suspected. But this view was quickly eliminated because the sources were so far away that the sizes of supernovae explosions would be too small to send the gamma rays all the way to our planet. The explosions must be much bigger. Eventually, it was concluded that these were hypernovae ; stars that explode with even greater violence than supernovae and then in a very short time collapse into and dissapear within the black holes that are formed in their centers. As matter is converted into energy gamma rays are emitted and radiated across the universe. These are the largest explosions since the big bang and our sky is full of them.
In the film, the question is raised what would happen if anyone of these explosions were to take place in the vicinity of the Earth ? The answer, the Earth would be burned all over at the same time in just a few seconds after the gamma rays reach us. However, what is the vicinity of the Earth is not explained or I missed it. Is it just the edge of our Solar System or is it a few light years away ?
The second part of the film is less interesting than the first part and talks about the hunt for supernovae and a supernova that was discovered in an observatory in Chile in1987, 170 thousand light years away from the Earth. Elsewhere on Earth an experiment conducted underground was able to catch a few of the countless number of neutrinos emitted into space by the neutron star formed by the supernova of 1987. Neutrinos are nuclear particles emitted by neutron stars and travel through space and through solid objects.
Subsequent comment on February 19th 2010 : In another documentary I watched on National Geographic Channel recently it was said that if a hypernova exploded within one thousand light years or closer to the Earth its gamma rays could be deadly. Over a thousand light years away we are safe. Fortunately, scientists think that none of the stars closer to us than a thousand light years are likely to emit gamma rays.