View the sky through an x-ray telescope and the conception of the universe changes dramatically. Black holes are best seen in x-rays, because impinging gas collides with the black hole at near light speed, resulting in intense x-ray and gamma ray emission.

Optical light also plays a role in discovering black holes since the most luminous objects in the universe emit bursts of gamma radiation which only lasts minutes, but leaves an optical afterglow.

The transcript and downloadable versions of the lecture are available from the Gresham College website: https://www.gresham.ac.uk/lectures-and-events/the-high-energy-universe

Gresham College has been giving free public lectures since 1597. This tradition continues today with all of our five or so public lectures a week being made available for free download from our website. There are currently over 2,000 lectures free to access or download from the website.

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