The star-gas-star cycle will keep the Milky Way looking just as bright in 100 billion years as it looks now.
The Correct Answer and Explanation is:
Correct Answer: False
Explanation
The statement that “the star-gas-star cycle will keep the Milky Way looking just as bright in 100 billion years as it looks now” is false.
The star-gas-star cycle refers to the process in which gas in galaxies like the Milky Way forms new stars, and when those stars die—particularly in supernova explosions—they return gas and elements to the interstellar medium, allowing the cycle to continue. This recycling process maintains the galaxy’s brightness and star formation over time. However, this process is not infinite.
Currently, the Milky Way is forming stars at a moderate rate—about 1–2 solar masses of stars per year. But the gas supply required for star formation is finite. Over billions of years, more gas is converted into stars or expelled from the galaxy by supernova-driven winds or interactions with other galaxies. Additionally, some gas cools inefficiently and becomes locked in forms that no longer contribute to active star formation.
Astronomical models suggest that the Milky Way will use up its star-forming gas in about 50 billion years. After that, star formation will sharply decline and eventually cease altogether. Without new stars forming, the galaxy’s stellar population will gradually age. The most luminous, massive stars burn out quickly (within millions of years), and over time, only longer-living, dimmer stars like red dwarfs will remain.
In 100 billion years, most of the bright, short-lived stars will be gone, and no new ones will replace them. The Milky Way will appear much dimmer than it does today. It will contain mostly old stars, stellar remnants like white dwarfs, neutron stars, and black holes, with very little gas remaining for new stars.
Therefore, the Milky Way will not look as bright in 100 billion years as it does now, making the original statement false.
