Science: Fourth State of Matter

Only recently have scientists realized that most of the universe is neither gaseous, liquid or solid. It is plasma, a lively, tricky, often dangerous state of matter whose distinctive characteristic is that its particles are electrically charged. Scientists call it “the fourth state of matter,” because plasma follows its own peculiar laws, responding to electrical forces and creating them. The sun and stars are mostly plasma; so are many loose particles moving in space between them. In fact, cosmologically speaking, only in a few exceptional places does matter settle down and become electrically neutral. But since the human race lives in one of those places—the cool outside of the planet Earth—its scientists came to think of neutral matter as the normal kind.

As man begins to reach out beyond his own planet into outer space, scientists are being forced to grapple with the fact that they live in a plasma universe. Said M.I.T. Physicist William P. Allis: “It is as if a people had lived all their lives in the mountains and then had come down to the edge of the ocean. Before they could use sea water or navigate through it, they would have to learn some things that would be perfectly obvious to anyone who had lived by the sea.” Last week the National Science Foundation announced grants of $500,000 to M.I.T. and $300,000 to Harvard to help humans understand the plasma ocean around them.

Neither university will build big apparatus. None is necessary; space-age man encounters many natural plasmas and creates many new ones. Fluorescent lamps are full of glowing plasma. The newly discovered Van Allen radiation belt, which surrounds the earth and stands as a threat to space-voyaging man. is a thin but dangerous plasma. The fireballs of nuclear explosions are made of plasma; so are electric arcs. When the warhead of a missile slams back into the atmosphere, it heats the air around it to 18.000° and turns it into an electrically charged plasma.

The plasma studies at Harvard and M.I.T. will be largely theoretical, but highly practical hardware is likely to grow out of them. The development of fusion power depends on better understanding of high-temperature plasmas. A plasma rocket engine expelling charged particles instead of hot gases may be the solution to the problem of long-range flight. During interplanetary voyages, a spaceship will pass through lashing streams of plasmas shot out of the sun, and its designers had better understand them well in advance. If a spaceship tries to land on a planet, it will meet another plasma problem. A group of Harvard scientists plans to simulate the atmospheres of Mars and Venus to see what sort of plasma will be created by a body entering them at spaceship speed.