What Is Radiation?

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Melvyn Bragg and guests Jim Al-Khalili, Frank Close and Frank James discuss the history of the discovery of radiation.Today the word 'radiation' conjures up images of destruction. But in physics, it simply describes the emission, transmission and absorption of energy, and the discovery of how radiation works has allowed us to identify new chemical elements, treat cancer and work out what the stars are made of.Over the course of the 19th century, physicists from Thomas Young, through Michael Faraday to Henri Becquerel made discovery after discovery, gradually piecing together a radically new picture of reality. They explored the light beyond the visible spectrum, connected electricity and magnetism, and eventually showed that heat, light, radio and mysterious new phenomena like 'X-rays' were all forms of 'electromagnetic wave'. In the early 20th century, with the discovery of radioactivity, scientists like Max Planck and Ernest Rutherford completed the picture of the 'electromagnetic spectrum'. This was a cumulative achievement that transformed our vision of the physical world, and what we could do in it.

Listen to the In Our Time episode on Radiation

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Short Article of the Day

The fear of ionising (nuclear) radiation is deeply ingrained in the public psyche. For reasons partly historical and partly psychological, we simply assume that any exposure to ionising radiation is dangerous. The dose doesn’t matter. The nature of the radioactive material doesn’t matter. The route of exposure – dermal, inhalation, ingestion – doesn’t matter. Radiation = Danger = Fear. Period.

The truth, however, is that the health risk posed by ionising radiation is nowhere near as great as commonly assumed. Instead, our excessive fear of radiation – our radiophobia – does more harm to public health than ionising radiation itself. And we know all this from some of the most frightening events in modern world history: the atomic bombings of Japan, and the nuclear accidents at Chernobyl and Fukushima....

Continue reading David Ropeik's article: Fear of radiation is more dangerous than radiation itself

Further Reading

In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:

  • electromagnetic radiation, such as radio waves, microwaves, visible light, x-rays, and gamma radiation (γ)
  • particle radiation, such as alpha radiation (α), beta radiation (β), and neutron radiation (particles of non-zero rest energy)
  • acoustic radiation, such as ultrasound, sound, and seismic waves (dependent on a physical transmission medium)
  • gravitational radiation, radiation that takes the form of gravitational waves, or ripples in the curvature of spacetime....

Continue reading the Wikipedia article on Radiation

Bonus Webcomic

Related Topics

 Entropy | Particle Physics | Quantum Mechanics

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