What Is the Universe Made of?

(THIS ARTICLE IS COURTESY OF LIVE SCIENCE)

 

What Is the Universe Made of?

Image of galaxy cluster Abell 2744 shows dark matter locations

In this image of galaxy cluster Abell 2744, a blue overlay shows the location of dark matter, which makes up about 75% of the cluster’s mass.
(Image: © NASA/ESA/ESO/CXC, and D. Coe (STScI)/J. Merten (Heidelberg/Bologna))

The universe is filled with billions of galaxies and trillions of stars, along with nearly uncountable numbers of planets, moons, asteroids, comets and clouds of dust and gas – all swirling in the vastness of space.

But if we zoom in, what are the building blocks of these celestial bodies, and where did they come from?

Hydrogen is the most common element found in the universe, followed by helium; together, they make up nearly all ordinary matter. But this accounts for only a tiny slice of the universe — about 5%. All the rest is made of stuff that can’t be seen and can only be detected indirectly. [From Big Bang to Present: Snapshots of Our Universe Through Time]

Mostly hydrogen

It all started with a Big Bang, about 13.8 billion years ago, when ultra-hot and densely packed matter suddenly and rapidly expanded in all directions at once. Milliseconds later, the newborn universe was a heaving mass of neutrons, protons, electrons, photons and other subatomic particles, roiling at about 100 billion degrees Kelvin, according to NASA.

Every bit of matter that makes up all the known elements in the periodic table — and every object in the universe, from black holes to massive stars to specks of space dust — was created during the Big Bang, said Neta Bahcall, a professor of astronomy in the Department of Astrophysical Sciences at Princeton University in New Jersey.

“We don’t even know the laws of physics that would have existed in such a hot, dense environment,” Bahcall told Live Science.

About 100 seconds after the Big Bang, the temperature dropped to a still-seething 1 billion degrees Kelvin. By roughly 380,000 years later, the universe had cooled enough for protons and neutrons to come together and form lithium, helium and the hydrogen isotope deuterium, while free electrons were trapped to form neutral atoms.

Because there were so many protons zipping around in the early universe, hydrogen — the lightest element, with just one proton and one neutron — became the most abundant element, making up nearly 95% percent of the universe’s atoms. Close to 5% of the universe’s atoms are helium, according to NASA. Then, about 200 million years after the Big Bang, the first stars formed and produced the rest of the elements, which make up a fraction of the remaining 1% of all ordinary matter in the universe.

Unseen particles

Something else was created during the Big Bang: dark matter. “But we can’t say what form it took, because we haven’t detected those particles,” Bahcall told Live Science.

Dark matter can’t be observed directly — yet — but its fingerprints are preserved in the universe’s first light, or the cosmic microwave background radiation (CMB), as tiny fluctuations in radiation, Bahcall said. Scientists first proposed the existence of dark matter in the 1930’s, theorizing that dark matter’s unseen pull must be what held together fast-moving galaxy clusters. Decades later, in the 1970’s, American astronomer Vera Rubin found more indirect evidence of dark matter in the faster-than-expected rotation rates of stars.

Based on Rubin’s findings, astrophysicists calculated that dark matter — even though it couldn’t be seen or measured — must make up a significant portion of the universe. But about 20 years ago, scientists discovered that the universe held something even stranger than dark matter; dark energy, which is thought to be significantly more abundant than either matter or dark matter. [Gallery: Dark Matter Throughout the Universe]

Hubble Space Telescope Image

Captured in 2014 by the Hubble Space Telescope, this picture of the evolving universe is among Hubble’s most colorful deep-space images.

(Image credit: NASA/ESA)

An irresistible force

The discovery of dark energy came about because scientists wondered if there was enough dark matter in the universe to cause expansion to sputter out or reverse direction, causing the universe to collapse inward on itself.

Lo and behold, when a team of researchers investigated this in the late 1990s, they found that not only was the universe not collapsing in on itself, it was expanding outward at an ever faster rate. The group determined that an unknown force — dubbed dark energy — was pushing against the universe in the apparent void of space and accelerating its momentum; the scientists’ findings earned physicists Adam Riess, Brian Schmidt and Saul Perlmutter the Nobel Prize in Physics in 2011.

Models of the force required to explain the universe’s accelerating expansion rate suggest that dark energy must make up between 70% and 75% of the universe. Dark matter, meanwhile, accounts for about 20% to 25%, while so-called ordinary matter — the stuff we can actually see — is estimated to make up less than 5% of the universe, Bahcall said.

Considering that dark energy makes up about three-quarters of the universe, understanding it is arguably the biggest challenge facing scientists today, astrophysicist Mario Livio, then with the Space Telescope Science Institute at Johns Hopkins University in Baltimore, Maryland, told Live Science sister site Space.com in 2018.

“While dark energy has not played a huge role in the evolution of the universe in the past, it will play the dominant role in the evolution in the future,” Livio said. “The fate of the universe depends on the nature of dark energy.”

Originally published on Live Science.

Our Galaxy’s Supermassive Black Hole Has Emitted a Mysteriously Bright Flare

(THIS ARTICLE IS COURTESY OF SCIENCE ALERT)

 

Our Galaxy’s Supermassive Black Hole Has Emitted a Mysteriously Bright Flare

MICHELLE STARR
12 AUG 2019

The supermassive black hole at the heart of the Milky Way, Sagittarius A*, is relatively quiet. It’s not an active nucleus, spewing light and heat into the space around it; most of the time, the black hole’s activity is low key, with minimal fluctuations in its brightness.

Most of the time. Recently, astronomers caught it going absolutely bananas, suddenly growing 75 times brighter before subsiding back to normal levels. That’s the brightest we’ve ever seen Sgr A* in near-infrared wavelengths.

“I was pretty surprised at first and then very excited,” astronomer Tuan Do of the University of California Los Angeles told ScienceAlert.

“The black hole was so bright I at first mistook it for the star S0-2, because I had never seen Sgr A* that bright. Over the next few frames, though, it was clear the source was variable and had to be the black hole. I knew almost right away there was probably something interesting going on with the black hole.”

But what? That’s what astronomers are on a mission to find out. Their findings so far are currently in press with The Astrophysical Journal Letters.

Do and his team took observations of the galactic center galaxy

using the WM Keck Observatory in Hawaii over four nights earlier this year. The strange brightening was observed on May 13, and the team managed to capture it in a time lapse, two hours condensed down to a few seconds.

Tuan Do@quantumpenguin

Here’s a timelapse of images over 2.5 hr from May from @keckobservatory of the supermassive black hole Sgr A*. The black hole is always variable, but this was the brightest we’ve seen in the infrared so far. It was probably even brighter before we started observing that night!

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That brightly glowing dot right at the beginning of the video is the dust and gas swirling around Sgr A*. Black holes themselves don’t emit any radiationthat can be detected by our current instruments, but the stuff nearby doeswhen the black hole’s gravitational forces generate immense friction, in turn producing radiation.

When we view that radiation with a telescope using the infrared range, it translates as brightness. Normally, the brightness of Sgr A* flickers a bit like a candle, varying from minutes to hours. But when the surroundings of a black hole flare that brightly, it’s a sign something may have gotten close enough to be grabbed by its gravity.

The first frame – taken right at the beginning of the observation – is the brightest, which means Sgr A* could have been even brighter before they started observing, Do said. But no one was aware that anything was drawing close enough to be swallowed by the black hole.

The team is busily gathering data to try and narrow it down, but there are two immediate possibilities. One is G2, an object thought to be a gas cloud that approached within 36 light-hours of Sgr A* in 2014. If it was a gas cloud, this proximity should have torn it to shreds, and parts of it devoured by the black hole – yet nothing happened.

The flyby was later called a “cosmic fizzle“, but the researchers believe the black hole’s May fireworks show may have been a delayed reaction.

sgr a s02(Do et al., arXiv, 2019)

But – have a look at the timelapse again. See that bright dot at around 11 o’clock from the black hole? That’s S0-2, a star on a long, looping, 16-year elliptical orbit around Sgr A*. Last year, it made its closest approach, coming within 17 light-hours of the black hole.

“One of the possibilities,” Do told ScienceAlert, “is that the star S0-2, when it passed close to the black hole last year, changed the way gas flows into the black hole, and so more gas is falling on it, leading it to become more variable.”

The only way to find out is having more data. They are currently being collected, across a larger range of wavelengths. More observations will take place over the coming weeks with the ground-based Keck Observatory before the galactic centre is no longer visible at night from Earth.

But many other telescopes – including Spitzer, Chandra, Swift and ALMA – were observing the galactic centre over the last few months, too. Their data could reveal different aspects of the physics of the change in brightness, and help us understand what Sgr A* is up to.

“I’m eagerly awaiting their results,” Do said.

The paper has been accepted into The Astrophysical Journal Letters, and is available on arXiv.

The 2-minute guide to Chinese astrology

(THIS ARTICLE IS COURTESY OF TRIVIA GENIUS)

 

The 2-minute guide to Chinese astrology

Half the fun of eating Chinese food comes from both the cryptic predictions that sprout from the crunch of a broken fortune cookie and from poring over place mats adorned with the Chinese zodiac. From time immemorial, humanity has searched for meaning in the stars, and many Chinese cultures have read the celestial canvas with curiosity and deeply-held mysticism.

The wisdom of Jupiter

Credit: LV4260 / iStock

The Chinese zodiac is based on early observations of the orbit of Jupiter. It is because of this that the zodiac occurs in 12-year cycles in accordance with the 11.85 years of Jupiter’s orbital period. The Chinese zodiac was founded during the Zhou Dynasty (1046-256 B.C.) and found widespread practice and elaboration during the Han Dynasty starting in 2nd century B.C.

It was during this second renaissance that Chinese astrology incorporated the cultural pillars of the Yin and Yang from Taoism, the concepts of heaven and earth, and Confucian ethics. The principles of Chinese astrology remain an object of fascination to Western cultures and a strong practice in many East Asian nations, including China, Japan, South Korea, Vietnam, and Thailand.

Written in the stars

Credit: cfikker / iStock

The Chinese zodiac is based on a strong conviction in destiny predicted from the alignment of the planets during one’s birth.

Your birth year predicts your sign and dictates many aspects of your disposition, romantic compatibility, and relation with your elders. However, in addition to your birth year, your “inner animal” is dictated by month, “true animal” by birthday, and “secret animal” by hour of birth.

Each sign is also associated with a “fixed element,” which interacts with a cycle of elements recurring in 60-year periods. Your birth month is still considered to be one of the most important predictors of your fate and disposition. Because of this, a Chinese astrologer would need to know the specific timing of your birth for a precise prediction. Even then, it is sometimes observed that a person’s behavior conflicts with his or her zodiac. This conflict is known as Tai Sui or kai sui.

The signs

Credit: Delpixart / iStock

Each sign corresponds to a year in Jupiter’s 12-year orbital cycle and an associated fixed element, starting with the first orbital year:

  • Rat-Water
  • Ox-Earth
  • Tiger-Wood
  • Rabbit-Wood
  • Dragon-Earth
  • Snake-Fire
  • Horse-Fire
  • Goat-Earth
  • Monkey-Metal
  • Rooster-Metal
  • Dog-Earth
  • Pig-Water
  • Monday-Goat
  • Tuesday-Dragon, Pig
  • Wednesday-Horse, Rooster
  • Thursday-Rat
  • Friday-Rabbit, Snake, Dog
  • Saturday-Ox, Tiger
  • Sunday-Monkey

Trines

Credit: humonia / iStock
  • Wood/Spring is a period of growth and vitality.
  • Fire/Summer is a period of flowering and energy.
  • Earth represents a transitory state between seasons.
  • Metal/Autumn is a period of harvesting.
  • Water/Winter is a period of retreat.
  • First Trine – The Rat, Dragon, and Monkey fall under the first trine, associated with intellect, magnanimity, and charisma, but capable of manipulation, jealousy, and deceit.
  • Second Trine – The Ox, Snake, and Rooster belong to the second trine, characterized by endurance, hard work, modesty, and morality, but capable of self-righteousness, egoism, vanity, and judgment.
  • Third Trine – the Tiger, Horse, and Dog pursue idealism, true love, loyalty, and honor, but may befall rashness, anxiety, and stubbornness.
  • Fourth Trine – The Rabbit, Goat, and Pig of the fourth trine are believed to be characterized by calm and reason, often sensible, creative, and empathetic, but prey to naiveté, pedantry, insecurity, and pessimism.