The combination of basic physical processes can often lead to surprisingly complex results and produce much of the intriguing cosmic order.

Science frontier questions related to understanding the cosmic order:

  • How do baryons cycle in and out of galaxies, and what do they do while they are there?

  • What are the flows of matter and energy in the circumgalactic medium?

  • What controls the mass-energy-chemical cycles within galaxies?

  • How do black holes grow, radiate, and influence their surroundings?

  • How do rotation and magnetic fields affect stars?

  • How do the lives of massive stars end?

  • What are the progenitors of Type Ia supernovae and how do they explode?

  • How diverse are planetary systems?

  • Do habitable worlds exist around other stars, and can we identify the telltale signs of life on an exoplanet?

One of the biggest challenges in the next decade is to understand how the basic building blocks of matter and energy, governed by known physical laws, are responsible for the dazzling array of astronomical phenomena that intrigue and inspire us. Meeting this challenge will require a synthesis of a broad range of evidence and insights drawn from traditionally disparate scientific disciplines.

None of the baryonic components of the cosmos (gas, galaxies, stars, planets, life) exist in isolation. Galaxies grow by cannibalizing smaller neighboring galaxies and by capturing primordial gas clouds flowing in from the vast spaces beyond. This gas, once inside a galaxy, is the raw material for forming new stars. The big bang produced only the simplest and lightest chemical elements, hydrogen and helium. Heavier elements like oxygen and iron have been forged within the nuclear furnaces of stars and violently expelled in supernova explosions, thereby seeding the environment with the material necessary to form planets and support life.

Our goal is to use all the applicable scientific laws to understand the properties and behavior of the cosmos—in short, to find order in complexity.

Galaxies and Black Holes

The observable universe contains more than 100 billion galaxies, including our own Milky Way. Although we commonly think of galaxies as being made of stars and clouds of gas and dust, in fact more than 90 percent of the mass of galaxies

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