麻豆传媒

Hillary Shaw
Newport, Shropshire, UK

I am not sure how a lump of antimatter as big as a meteor would form or survive in interstellar space, but suppose one did. Say it is 10 脳 10 脳 10 metres, and let鈥檚 give it similar properties to rock, specifically a heat capacity of 2000 joules per kilogram, and a density of 2.5 grams per cubic centimetre. The solar system has about 10⁶ hydrogen atoms per cubic metre at its outer edges, rising to 10⁷ in the vicinity of Earth.

The distance from a little beyond Pluto鈥檚 orbit to the sun is about 10¹³ metres, so along this path this antimatter 鈥渕eteor鈥� would encounter, and annihilate to energy, some 10²² hydrogen atoms, total mass 10^-2 kg. That produces about 10¹⁵ J of energy. Based on these figures, it would take around 10¹⁰ J to heat this antimeteor by 1掳C, so, neglecting energy losses by radiation, it should heat up to a toasty 10⁵掳C. Even at 10⁴掳C, it would glow white, and at 10⁵掳C it would be blue-white, emitting mainly UV and X-rays. We would probably spot that.

If it hit the sun, the resulting explosion as it all annihilated would probably destroy all life on Earth. Any planet it hit, including Jupiter, would be instantly destroyed. If it hit Neptune, we might survive for a while, with spectacular night shows, but the gravitational disturbances might change our orbit and kill us all later via heat, cold or meteorite strikes.

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