Fact-check log

The Big Bang, Nobel laureate John Mather says in a NASA Q&A, is a really misleading name for the expanding universe that we see. NASA

The name, he says, conveys the idea of a firecracker exploding at a time and a place — with a center. NASA

The universe doesn't have a center. The Big Bang happened everywhere at once and was a process happening in time, not a point in time. NASA

We know this, he says, because we see galaxies rushing away from each other, not from a central point, and because leftover heat uniformly fills the universe. NASA

The Big Bang itself is not something we can see. NASA

We can see the heat that was there at about 380,000 years after the expansion of the universe began 13.8 billion years ago (which, in that Q&A, is what is referred to as the Big Bang). NASA

This heat covers the entire sky and fills the universe. It still does. NASA

It was mapped with satellites NASA and ESA built: COBE, WMAP and Planck. The universe at that point was extremely smooth, with only tiny ripples in temperature. NASA

COBE, WMAP and Planck all saw further back than JWST, though JWST will see farther back than Hubble. JWST was designed not to see the beginnings of the universe, but a later period, perhaps hundreds of millions of years after the one those missions were built to see. NASA

Mather says the tiny ripples of temperature they observed were the seeds that eventually grew into galaxies. We don't know exactly when the universe made the first stars and galaxies — or how. NASA

Mather shares the 2006 Nobel Prize for Physics with George F. Smoot for their work using the COBE satellite to measure the heat radiation from the Big Bang. NASA

The chemical elements of life were first produced in the first generation of stars after the Big Bang. Those first stars produced the other chemical elements besides hydrogen and helium. NASA

A NASA Hubble page says the big bang theory of the universe starts with a single point which rapidly expanded and slowly evolved into the cosmos we see today. NASA

Some 13.8 billion years ago, that page says, the universe was a dense, tremendously hot (too hot for the existence of atoms), extremely tiny point that rapidly surged outward in all directions. NASA

For a fraction of a second, the universe expanded faster than the speed of light. We do not know what triggered that initial, rapid expansion, but this period, called cosmic inflation, explains much of what we see in the universe today. NASA

About one second after the big bang, the rapid expansion slowed. The universe was an extremely hot, uniform, cosmic soup of subatomic particles and light. NASA

A few minutes after the big bang, the universe had cooled enough for subatomic particles to form atomic nuclei. Protons and neutrons formed the nuclei of hydrogen and helium, the basic building blocks of stars. NASA

It would be some 380,000 years before the universe cooled enough for these nuclei to capture electrons, forming the atoms we are familiar with today. As they became part of atoms, the captured electrons slowed down, releasing some of their energy that we detect as cosmic microwave background radiation today. NASA

A NASA illustration on the same page represents the evolution of the universe over 13.77 billion years. NASA

For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate. NASA

Gravitational lumps eventually formed a cosmic web of filaments and vast sheets of matter that shape the underlying structure of the universe we see today. NASA

In a Nobel Prize winning discovery, Hubble uncovered the acceleration of our expanding universe along with ground-based observatories. NASA

Helium nuclei were created in the Big Bang and contain two protons and two neutrons each. Helium is the second most abundant element, comprising roughly one quarter of the mass of the universe. NASA

NASA says WMAP measured the cosmic microwave background radiation over the full sky. This microwave radiation was released approximately 375,000 years after the birth of the universe. NASA

WMAP measured small variations in temperature. For example, one part of the sky has a temperature of 2.7251° Kelvin, while another has 2.7249° Kelvin. NASA

In 1992, NASA's COBE satellite discovered these tiny temperature differences on large angular scales. WMAP measured anisotropy with much finer detail and greater sensitivity than COBE did. NASA

WMAP, NASA says, determined the universe to be 13.77 billion years old to within a half percent. NASA

It nailed down the curvature of space to within 0.4% of “flat” Euclidean. NASA

Ordinary atoms (also called baryons) make up only about 5% of the universe, in WMAP's census. NASA

Dark matter (matter not made up of atoms) is about 25.0%. NASA

Dark energy, in the form of a cosmological constant, makes up about 70% of the universe, causing the expansion rate of the universe to speed up. NASA

WMAP results support inflation: the idea that the universe underwent a dramatic period of expansion, growing by more than a trillion trillion fold in less than a trillionth of a trillionth of a second. NASA

The WMAP mission launched on 30 June 2001. It was renamed after team member David T. Wilkinson. It ended the collection of science data on 19 August 2010. NASA

The afterglow light seen by WMAP was emitted about 375,000 years after inflation and has traversed the universe largely unimpeded since then. NASA

The cosmic microwave background, a NASA Physics of the Cosmos page says, originated just 380,000 years after the Big Bang, when the Universe was dense, hot, and opaque. NASA

We observe that same light today, stretched by the expansion of the universe to a cold 2.7K glow. NASA

Maps of the CMB provide a precise measurement of the geometry of the Universe, and show that it is “flat,” governed by Euclidean geometry on cosmic scales. NASA

The detailed properties of CMB maps are consistent with the predictions of inflation. However, the physical process behind inflation remains unknown. NASA

The cosmic microwave background, NASA says, is the oldest light we can observe in the universe. NASA

The universe's first stars were 30 to 300 times more massive than our Sun and millions of times brighter. NASA

New ideas and major discoveries made during the 20th century transformed cosmology, NASA says, although much remains unknown. NASA

The big-bang model, Britannica says, is a widely held theory of the evolution of the universe. Its essential feature is the emergence of the universe from a state of extremely high temperature and density — the so-called big bang that occurred 13.8 billion years ago. Britannica

This type of universe was proposed by Aleksandr Friedmann and Georges Lemaitre in the 1920s. The modern version was developed by George Gamow and colleagues in the 1940s. Britannica

The cosmological principle, Britannica says, implies that the universe has no edge, so that the big-bang origin occurred not at a particular point in space but rather throughout space at the same time. Britannica

These assumptions make it possible to calculate the history of the cosmos after a certain epoch called the Planck time. Scientists have yet to determine what prevailed before Planck time. Britannica

After a few seconds, the universe cooled enough to allow the formation of certain nuclei. The theory predicts that definite amounts of hydrogen, helium, and lithium were produced. Their abundances agree with what is observed today. Britannica

About one million years later the universe was sufficiently cool for atoms to form. The radiation that also filled the universe was then free to travel through space. Britannica

This remnant is the cosmic microwave background radiation — the “three degree” (actually 2.728 K) background radiation — discovered in 1965 by Arno A. Penzias and Robert W. Wilson. Britannica

The detection of extragalactic redshift by Vesto Slipher, Britannica says, led to the realization in the 1920s that all galaxies are receding. Britannica

Edwin Hubble correlated these observations in mathematical form to provide evidence that the universe is expanding. Britannica

The discovery of the 2.7 K cosmic microwave background radiation in 1965 by Arno Penzias and Robert Wilson was convincing evidence that the universe originated 13.8 billion years ago from a very dense and hot state in the big bang. Britannica

For much of the 20th century, it was an open question whether the universe in the future will continue to expand indefinitely or will eventually collapse back. Britannica

The dark matter that has been deduced from various dynamic arguments is about 23 percent of the universe, and dark energy supplies the remaining amount, bringing the total average mass density up to 100 percent of the closure density. Britannica

The cosmic microwave background, Britannica says, is electromagnetic radiation filling the universe that is a residual effect of the big bang 13.8 billion years ago. Britannica

Beginning in 1948, George Gamow, Ralph Alpher and Robert Herman investigated the idea that the chemical elements might have been synthesized in a primeval fireball, and calculated that the leftover radiation temperature would have dropped to about 5 kelvins. Britannica

The actual discovery occurred by accident. Arno Penzias and Robert Wilson, of Bell Telephone Laboratories, Holmdel, New Jersey, measured excess radio noise that seemed to come from the sky in every direction, in experiments connected with the first Telstar communication satellite. Britannica

The two groups published simultaneously in 1965 papers detailing the prediction and discovery of a universal thermal radiation field with a temperature of about 3 K. Britannica

Precise measurements made by the COBE satellite launched in 1989 determined the spectrum to be exactly characteristic of a blackbody at 2.735 K. Britannica

WMAP’s measurements, in Britannica wording, showed that today the universe is 72.6 percent dark energy, 22.8 percent dark matter, and 4.6 percent atoms. Britannica

WMAP also showed, that article says, that the first stars in the universe formed half a billion years after the big bang. Britannica

At a redshift of about 1,090, radiation would have decoupled from matter when hydrogen recombined. These photons from a redshift of 1,090 form the cosmic microwave background. Britannica