by Kim Malville
What’s happening in the skies this month?
April 3: The crescent moon passes through the Hyades star cluster, slightly above and to the right of bright red Aldebaran (the bloodshot eye of Taurus, the Bull). The leading edge of the moon will be dark and will occult (hide) several of the medium-bright stars in the cluster beginning soon after sunset. Binoculars will add to the enjoyment.
April 6: The half-moon will be close to Jupiter.
April 8: Mars is in opposition to the sun, rising at sunset, setting at sunrise, due south at midnight.
April 14/15: Total eclipse of the moon. The partial eclipse begins when the moon first moves into the earth’s shadow at 11:58pm, local time. The total eclipse begins at 1:07am when the moon is fully in the earth’s shadow, completely shielded from the sun. Totality lasts until 1:46am. Don’t miss it!
April 27: Solar eclipse visible in the Antarctic.
Biggest discovery in decades: Gravity waves in the early universe
On March 17 the newspapers and TV stations announced the discovery of the influence of gravity waves on the early universe. This is a discovery that may rank with the discovery of dark energy or background radiation of the universe, and, if confirmed, should result in a Nobel Prize.
I shall try to explain these new findings because they have such amazing philosophical and even theological implications. These are difficult ideas, and I hope I can succeed. Basically the news that lit up switchboards around the world was that a team of astronomers led by John M. Kovac of the Harvard-Smithsonian Center for Astrophysics detected ripples in the cosmic background radiation. Those ripples were produced by gravitational waves when the universe was first torn apart by cosmic inflation. The cosmic background radiation completely surrounds us, and it is as close as we can come to the beginning of our universe, using light as a probe. An impenetrable barrier lies at a distance of 13.8 billion light years. It is known as the photosphere of the universe, since it is sort of like the photosphere of the sun. It is the face of the primordial fireball of creation when time and space were only 380,000 years old. Beyond that barrier the universe is too dense for light waves to penetrate.
Gravity interacts with matter much more weakly than light, and now it appears we have received a message via gravity waves that originated when the universe was roughly a trillionth of a trillionth of a trillionth of a second old.
These results were obtained by the telescope known as BICEP2 (Background Imaging of Cosmic Extragalactic Polarization) at the South Pole. BICEP is the building-mounted dish on the left in the figure. Gravity waves squeeze space in one direction and stretch it in another and twist the direction of polarization of the microwave radiation. As a result a map of the polarization of the fireball shows little arrows going in spirals as is shown in the insert. Polarization of light refers to the direction of vibration of light waves, and we all experience its effects when wearing polarized sunglasses.
The history of the universe showing the episode of inflation (NSF: BICEP2 team)
Gravity waves require moving huge amounts of matter to start the vibrations in space. That apparently happened during the really mysterious period of cosmic inflation, which is the neck of the cosmic bottle in the figure which is not drawn to scale. The universe increased in size by a trillion trillion at that time, expanding faster than the speed of light.
Why was the theory of inflation proposed in the first place? When an astronomer photographs a galaxy at a distance of ten billion light years, it appears as it was ten billion years ago. If the astronomer turns to photograph a galaxy ten billion light years away in the opposite direction, he would be seeing two galaxies separated from each other by twenty billion light years. This means that the light from the first has not yet reached the second, because the 13.8 billion-year-old universe is not old enough to allow information to pass from one such galaxy to the other. As we understand physics now, no information inside our universe can travel faster than the speed of light. In other words, there are regions of the universe that are visible to us, but are invisible to each other!
Since these two galaxies separated by 20 billion light years cannot have shared information with each other, one would expect that their physical properties would be different. More generally, the universe should have varying properties in different areas. However, the universe is strangely uniform. The cosmic microwave background radiation, which fills the universe, is almost precisely the same temperature everywhere in the sky, about 2.728 +/- 0.004 degrees above absolute zero. This bizarre uniformity presents a serious scientific and philosophical dilemma: if the universe had started with even slightly different temperatures in different areas, then there would be no ordinary way it could have evened itself out to a common temperature.
The theory of cosmic inflation postulates that during an incredibly short period of time our universe increased in size by an enormous factor, from an infinitesimally small speck to the size of a grapefruit. Before inflation the universe was small enough to be thoroughly interconnected and temperature would have been evened out. Inflation suddenly expanded the universe, locking in the uniformity over today’s large distances. That incredibly powerful expansion produced those gravity waves that produced the wrinkles in the ancient face of the primordial fireball.
One absolutely stunning conclusion of this theory is that while our own universe has settled down to today’s comfortable expansion, the rest of the cosmos will continue blowing bubbles of other universes. Creation events should continue forever in the vastness of the super-universe out of which we emerged 13.8 billion years ago. One cannot imagine what wonders these other universes must contain.