Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all
The cosmic story of us, from before the Big Bang until today, is a story that all of us share. Enjoy it, in just 200 words.
In the beginning, there was space and time, and the fabric of space was expanding at a fantastic rate.
A representation of flat, empty space with no matter, energy or curvature of any type. With the exception of small quantum fluctuations, space in an inflationary Universe becomes incredibly flat like this, except in a 3D grid rather than a 2D sheet. Space is stretched flat, and particles are rapidly driven away. (AMBER STUVER / LIVING LIGO)
That inflationary state came to an end where we are, converting the energy of space into matter, antimatter and radiation.
The Big Bang produces matter, antimatter and radiation, with slightly more matter being created at some point, leading to our Universe today. How that asymmetry came about, or arose from where there was no asymmetry to start, is still an open question. (E. SIEGEL / BEYOND THE GALAXY)
This hot, primordial soup expanded and cooled, creating a slight asymmetry between matter (slightly more) and antimatter (slightly less).
In the hot, early Universe, prior to the formation of neutral atoms, photons scatter off of electrons (and to a lesser extent, protons) at a very high rate, transferring momentum when they do. After neutral atoms form, owing to the Universe cooling to below a certain, critical threshold, the photons simply travel in a straight line. (AMANDA YOHO)
The cooling continued, nuclei formed, and eventually, so did neutral atoms.
An artist’s conception of what the Universe might look like as it forms stars for the first time. As they shine and merge, radiation will be emitted, both electromagnetic and gravitational. The neutral atoms surrounding it get ionized, but as long as there are more neutral atoms around them, the light won’t penetrate through an arbitrary distance.(NASA/ESA/ESO/WOLFRAM FREUDLING ET AL. (STECF))
These atoms clumped together in gravitationally overdense regions, forming the first stars after tens of millions of years.
A supernova explosion enriches the surrounding interstellar medium with heavy elements. This illustration, of the remnant of SN 1987a, showcases how the material from a dead star gets recycled into the interstellar medium. (ESO / L. CALÇADA)
The most massive stars run out of fuel and die in supernovae, enriching the Universe with heavy elements.
On larger scales, star clusters, galaxies and more merge together to form the large-scale structure we see today.
This spectacular image of the Orion Nebula star-formation region was obtained from multiple exposures using the HAWK-I infrared camera on ESO’s Very Large Telescope in Chile. New stars are still forming in this nebula, but they’re almost done doing so, as the hot, young stars are boiling all potential star-forming gas away. (ESO/H. DRASS ET AL.)
On small scales, generations of recycled, burned-out stellar material give rise to new generations of stars.
The protoplanetary disk around the young star, HL Tauri, as photographed by ALMA. The gaps in the disk indicate the presence of new planets. Once enough heavy elements are present, some of these planets can be rocky. This system is already hundreds of millions of years old, and the planets there are likely nearing their final stages and orbits. (ALMA (ESO/NAOJ/NRAO))
These later generations contain 1–2% heavy elements, some of which form rocky planets.
When planets, stars, and new generations of material form, they do so out of all the material that came before. The existence of rocky planets, complex molecules, and biological processes requires numerous generations of stars to live-and-die first. (ESA, NASA, AND L. CALCADA (ESO FOR STSCI))
Some of these planets, rich with life’s fundamental ingredients, form in the habitable zones of their stars.
The Earth and Sun, not so different from how they might have appeared 4 billion years ago. Yet daily or even hourly changes can tell us incredible information about near-term environmental and ecological threats to our world. (NASA/TERRY VIRTS)
On one of them, 4+ billion years ago, life takes hold.
Humans looking at Mirador Crater in Costa Rica. The path of evolution that led to human being existing in their current form, today, was by no means a given, but we are here to enjoy the fruits of that chance outcome. (MARIO ROBERTO DURAN ORTIZ)
After evolution, catastrophes, and extinction, we, the survivors, arrived.
Mostly Mute Monday tells the story of a single scientific phenomenon or object primarily in visuals, with no more than 200 words of text. Talk less; smile more.
