Planet Formation Requires Metals

Planet Formation Requires Metals

If humanity is so important, why is the universe so old? Chapter 3 of Why the Universe Is the Way It Is, by Hugh Ross, provides a few answers to this important question. Recent research offers additional explanation.

Human beings (and all life it seems) require a home abounding in liquid water. This requirement necessitates an abundance of elements heavier than helium (which astronomers refer to as metals). However, shortly after the big bang creation event, almost no metals existed until stars began fusing hydrogen and helium into these heavier elements. These stars died in catastrophic explosions that scattered the metals into the cosmos, thus allowing future stars to incorporate them. This buildup of metals enabled the formation of smaller, longer-lived stars suitable for life-friendly planets. But it appears that the metal content of the universe also affects planet formation.

As briefly described in a previous TNRTB, planet building starts when a condensing gas cloud forms a disk of dust, gas, and pebbles. For stars similar in mass to the Sun, the early stages of this process also involve a strong wind emanating from the star. This wind tends to blow the gas and dust out of the region where planets would form. Thus, the planets must form before all the building material blows away.

Sun-like stars (those with similar metal content) blow away their gas and dust in 5-10 million years. According to a study recently published in the Astrophysical Journal, stars forming from metal-poor gas clouds clear out the dust and gas disks in less than one million years. That’s five to ten times faster than stars with Sun-like metallicity. In these metal-poor environments, insufficient amounts of heavy elements and a lack of time make planet formation difficult.

In a related article, a different group of scientists determined that the ability of gas, dust, and pebbles to clump together and form planetesimals (kilometer-sized objects that eventually coalesce into planets) also depends on the metallicity. The higher the metallicity of the condensing gas cloud, the more readily planetesimals grow. In fact, the research indicates that the threshold for planetesimal formation exists right near the metal abundance of the Sun.

This research (along with a previously discussed discovery) provides a good answer to why the universe is so old. It shows that the universe needed to be over nine billion years old before a planet like ours could form. Just as RTB’s creation model predicts, God created Earth—and introduced human beings—as soon the universe was prepared.