2015-05-15 BBC:星光七纪元-34(在线收听

 He was sure that when a supernova exploded, it left behind a kernel so dense that a cupful would be as heavy as a mountain, he called it a neutron star, it seems so preposterous that Z's ideas were dismissed, until that is a new way of scouring the heavens emerged, radio astronomy. In 1967 the fledgling displine picked up a strange repetitive message from outer space.Now the people here say that if they got three signals as exactly space as that, it would be very unusual, if they got four, it would be phenomenal, well they've had pulses as exactly space as that 24 hours of the day since November.

These pulses were so exact and predictable in their pattern that scientists even considered aliens as their source, it turned out they were being transmitted by something equally unlikely and just as unfamiliar.
The most important question of all what are they, well we know that they are very small, they are objects about the size of a planet, we know also that they are very energetic and the source of energy must be far greater than a planet could really provide, it must be something like a star compressed into a volume the size of a planet.
Scientists worked out that the new star had to be denser than any type previously discovered.
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