Meg Urry : The Two-WayA new study finds that the number of people who are obese in America has doubled since 1980. But it has its practical value , well beyond the primary goal of understanding how the present-day universe -- and our Earth , Solar System and Milky Way galaxy -- came to be . Urry : There is enough mass in the wind to carry away a lot of gas in the galaxy . She says this suggests an answer to why galaxies today do not have more stars . Urry : It 's because cold gas , which forms stars , is being blown out of galaxies .
Meg Urry : The Two-WayA new study finds that the number of people who are obese in America has doubled since 1980. Urry : There is enough mass in the wind to carry away a lot of gas in the galaxy . She says this suggests an answer to why galaxies today do not have more stars . Urry : It 's because cold gas , which forms stars , is being blown out of galaxies .