Science: Bridges in Space

Astronomers have long known that the space between the stars contains a good bit of gas, dust, and probably larger chunks of unattached matter. The space between galaxies, however, they believed to be virtually empty. The only exceptions they knew about were faintly luminous filaments that seemed to connect a few galaxies.

This week Astrophysicist Fritz Zwicky of CalTech announced his conclusion that these filaments are probably the rule in space, rather than the exception. With the 48-inch Schmidt telescope on Palomar Mountain he found hundreds of luminous “bridges” connecting widely separated galaxies. The length of one curved bridge, sharp as a lighted boulevard, is more than 72,000 light-years (430,000 trillion miles).

The light from the bridges of space almost certainly comes from stars, but because of the enormous distances, no individual stars have been picked out so far. In some parts of the bridges the light is reddish, in other parts bluish. This probably means that red or blue stars predominate in different sections.

The importance of Zwicky’s discovery has not yet been determined. Zwicky believes that the bridges must contain dust and gas as well as stars. If this turns out to be true, and if the bridges prove to be very common, astronomers may have to raise their estimate of the amount of matter in the universe. Such a change will affect the calculations of cosmologists, who are trying to figure out how the universe was formed and how it is developing. The total mass of matter is one of their key figures.

Another possible effect of the Zwicky discovery may be to change astronomers’ ideas about distances in space. If it turns out that the new-found bridges wind thickly among the nearer galaxies, they must dim the light from galaxies behind them, making them appear more distant than they are.

No one is sure so far how the bridges were formed. Zwicky suspects that they may be stellar debris that was scattered through space by near-collision between galaxies. Another possible theory: that they may be made of matter that was somehow outside when the galaxies contracted to their present forms.