Name: 輻射如何改變你的DNA (How Radiation Changes Your DNA)
Uploaded: 2021-01-14T06:04:47.000Z
Duration: 4 min 14 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

What do your phone, the sun, the stove, far-off black-holes and the palm of your hands all

have in common? Radiation, baby. It's everywhere.

Up and atom friends, Trace here emitting and absorbing radiation at your eyeballs for DNews!

When I say radiation, most people do this, but to be honest, radiation on it's own isn't

necessarily harmful! The term radiation is super broad, gamma rays shooting out of stars

is radiation, heat coming off the pavement on a hot day is radiation, and the radio waves

picked up and emitted by cell phones, radio stations and WiFi networks are radiation too

-- even the light you're seeing on this screen is radiation. The thing is, even though radio,

microwave, visible and infrared, are technically radiation -- when we SAY radiation, most people

think of dangerous high-energy particles called IONIZING radiation. That includes Ultraviolet,

X-Rays, or Gamma Rays. Which makes sense, but what can that stuff DO to you when it

In 1927, in the journal Science, Hermann Muller published a paper showing the ionizing radiation

of x-rays damaged the genes of fruit flies. He later won a Nobel prize! Ionizing radiation

is high-energy radiation… it's got a lot of energy. When this high-energy particle

or wave hits an atom, the atom absorbs the energy; causing the weakest electron to pop

off! This creates a charged atom called an ion!

Do that enough and all that high-energy can cause chemical changes in our tissue. If ionizing

radiation affects too many cells at once, or we absorb a bunch over time -- that's when

we risk sickness, radiation poisoning, or eventually cancer. That happens when the radiation

changes how things fit together. It might knock off bits of our DNA, mess with its structure,

or (at worst) break one or both strands of the DNA double helix! That alone isn't damaging,

but sometimes, the body makes mistakes when repairing that damage -- causing wide-spread

But chances are, you'll never have to worry too much about how much radiation you're being

exposed to. Radiation dosage is measured in sieverts. One sievert in a short time can

cause radiation sickness and 10 can kill. But because we'd never really encounter a

full sievert, scientists usually talk in millisieverts. Every year, just living on Earth exposes us

to 2.4 mSv in natural background radiation, and its fine. A chest x-ray, for example,

is 6.8 mSv, so while ONE X-Ray won't hurt you, a bunch throughout your life (or all

at once) can damage your tissues enough to cause health problems.

If that weren't complicated enough, there are different types of ionizing radiation!

Alpha, Beta, Gamma and X-Rays; listed in increasing energy levels. Alpha radiation is the slow

big fella, it can't really penetrate your body, but it's essentially a handful of protons

and neutrons. Beta is basically a tiny fast-moving electron; it can penetrate your body, but

not some denser materials, like aluminum. Then there's gamma radiation, which is just

fast-moving pure energy! It's so small it can pass between your cells, but if it hits

your DNA it'll mess you up -- though it won't make you green and invulnerable. In fact gamma

so high energy, it can pass though you, aluminum and even concrete walls -- though not lead

it's too dense. X-Rays are like gamma rays, but lower energy.

In the end, you probably don't have to worry a LOT about ionizing radiation. UV rays can

damage DNA over time, so wear sunscreen. X-Rays are highly regulated, and hopefully you haven't

spent too much time near unbridled nuclear reactions, or exposed yourself to cosmic rays.

Most radiation is just regular non-ionizing stuff. Heck, even humans emit infrared radiation

in the form of heat and some ionizing radiation that we absorb from food, like bananas. It's

everywhere! And though some of it can damage you, it's not all bad.