Category Archives: Universe Mysteries

A detailed spiral galaxy with a bright core and swirling arms filled with countless stars against a dark background.

Can Galaxies Form New Stars from Nothing?

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In recent years, astronomers have been puzzled by formidable mystery. Galaxies don’t appear to have enough raw material within them to form new stars at the rate they do. The Milky Way, for example,  turns about one solar mass’ worth of matter into new stars every year, despite the apparent lack of star forming raw material, such as gas and dust.. Even more perplexing, astronomers believe that galaxies expel gas and dust into outer space due to various processes within the galaxies, such as  supernova explosions of dying stars, as well as the force of radiation from bright stars. This would seem to suggest that galaxies are losing star forming material and should be unable to continue to form new starts at the rate they do.

Recently, Kate Rubin of the Max Planck Institute for Astronomy in Germany, leading a team of astronomers, used the Keck I telescope on Mauna Kea in Hawaii to observe 100 galaxies between 5 and 8 billion light-years away from Earth. They made a startling discovery. For six of the galaxies they observed, gas adrift in space was being recaptured by the galaxies and flowing back into their centers. This confirmed a long held suspicion that the gravitational attraction of galaxies would eventually recycle the gases expelled and use it to form new stars.

However, no such observation was made regarding the other 94 galaxies. Astronomers believe this is because it is difficult to detect the gas flow, which is dependent on the orientation of the galaxy. Essentially, they believe galactic recycling is occurring, but they are unable to confirm it. “This is a key piece of the puzzle and important evidence that cosmic recycling (‘galactic fountains’) could indeed solve the mystery of the missing raw matter,” according to a Max Planck Institute for Astronomy statement.

However, before we breakout the champagne, be aware that galactic recycling may not explain the entire mystery. It’s not clear that galaxies are capturing enough material to account for the amount of formation of new starts. Arguably, the most fundamental law in physics is the conservation of energy This suggests that the material to form new stars is coming from some place. If galactic recycling isn’t the total answer, we must look to other possible sources, perhaps even dark matter.

The universe is still extremely mysterious and our understanding has just scratched the surface. Galactic recycling is likely an important piece of the puzzle regarding new star formation. Like all great mysteries in science, it takes time to get and place all the puzzle pieces before the puzzle picture becomes clear.

 

 

Aerial view of a desert observatory complex with large telescopes mounted on platforms, set against mountainous terrain.

Where Is All the Lithium?

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According to standard cosmology theory, Lithium, together with hydrogen and helium, is one of three elements to have been synthesized in the Big Bang. Therefore, we should see a uniform abundance of Lithium throughout the universe. However, we don’t. By experimental observation, the older stars seem to have less Lithium than they should (by a factor of 2 or 3), and some younger stars have far more. This discrepancy regarding the uniform abundance of Lithium and experimental analysis of older stars is one of the most distressing discrepancies with the Big Bang theory. In science, one significant discrepancy can dispute a theory. Therefore, this raised serious questions regarding the validity of the Big Bang theory and cast doubt on the accuracy of the experimental measurements.

In 2006, astronomers Andreas Korn of Uppsala University in Sweden and colleagues in Denmark, France and Russia made an important discovery regarding the Lithium cosmic discrepancy. Using a spectrometer on the European Southern Observatory’s Very Large Telescope in Chile, Korn and co-workers studied 18 stars in a distant globular cluster called NGC 6397, which formed roughly a few hundred million years after the Big Bang. Using their experimental data along with theoretical models of how nuclei behave in the atmospheres of stars, they put forward a new model. They hypothesized that the lithium diffuses into the interiors of stars over time, where it is burnt up at temperatures of over 2.5 million Kelvin. Their model suggested that these stars originally contained 78% more lithium than we observe today. In other words, the predicted initial amount of Lithium agrees with predictions from the Big Bang theory.

Even after Korn’s (and colleagues) discovery in 2006, some cosmologists continued to entertained a competing theory, namely that axions, hypothetical subatomic particles, may have absorbed protons and reduced the amount of Lithium created in the period just after the Big Bang. The axion particle was postulated by the Peccei–Quinn theory in 1977 to resolve the “strong CP problem” (CP standing for charge parity). In theoretical physics, quantum chromodynamics (QCD), the theory of strong interactions, predicted there could be a violation of CP symmetry in the strong interactions (the mechanism responsible for the strong nuclear force that holds the nucleus of the atom together). However, there is no experimentally known violation of the CP-symmetry in strong interactions. In effect, cosmologists forwarding the axion theory to explain the cosmological Lithium discrepancy are attempting to explain one mystery (i.e., the cosmological Lithium discrepancy) with another mystery (hypothetical axions). Although, the strong CP problem continues to remain one of the most important unsolved problems in physics, axions appear to be a far less plausible solution to the cosmological Lithium discrepancy. If we apply Occam’s razor (i.e., the simplest of competing theories is preferred to the more complex or that explanations of unknown phenomena be sought first in terms of known quantities), Korn’s (and colleagues) model triumphs.

If we accept Korn’s (and colleagues) model, one of the great cosmological mysteries is resolved and questions regarding the Big Bang model  and the experimental measurements are resolved. However, in science old paradigms seem to only die when the scientists holding them die. In my judgement, Korn and his colleagues have resolved the missing Lithium question and are potential candidates for the Nobel Prize.

Image: The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile

A spiral galaxy with bright purple jets emitting from its center against a star-filled cosmic background.

What Are Fermi Bubbles?

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In 2010, astronomers using NASA’s Hubble Space Telescope observed giant balloon-like features emanating from the Milky Way core. The balloon-like featured are termed “Fermi Bubbles” and consist of clouds of gas towering about 30,000 light-years above and below the plane of our Milky Way Galaxy. The Fermi Bubbles are made up of super-high-energy gamma-ray and X-ray emissions, which are invisible to the naked eye.

What is causing the Fermi Bubbles is a mystery. Some scientists have hypothesized that the gamma rays might be shock waves from stars being consumed by the massive black hole at the center of the galaxy. Others suggest it may be due to a firestorm of star birth at the galactic center.

Although, we have seen similar structures emanating from the core of other galaxies, the 2010 discovery was the first time we observed the phenomena in our own galaxy, which gives us a rare close up view of the phenomena. “When you look at the centers of other galaxies, the outflows appear much smaller because the galaxies are farther away,” Dr Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland, told NASA (January 5, 2015). Dr. Fox added, “the outflowing clouds we’re seeing are only 25,000 light-years away in our galaxy. We have a front-row seat. We can study the details of these structures. We can look at how big the bubbles are and can measure how much of the sky they are covering.”

Dr Fox and his colleagues the United States, Italy and Australia used Hubble’s Cosmic Origins Spectrograph (COS) to determine:

  • The gas on the near side of the bubble is moving toward Earth and the gas on the far side is traveling away.
  • The gas is rushing from the Galactic center at roughly 3 million km per hour.
  • The gas contains silicon, carbon, and aluminum, which indicates the gas is enriched in the heavy elements produced inside stars and represents the fossil remnants of star formation.
  • The average temperature of the gaseous bubbles is thought to be approximately 18 million degrees Fahrenheit.

The next step is to calculate the mass of the material being blown out of our galaxy, which could help determine the cause of the outburst. This could provide a vital clue to the mystery of how the Fermi Bubbles formed. Most scientists suggest a powerful event took place millions of years ago, likely when the black hole at the center of our galaxy consumed an enormous amount of gas and dust (perhaps several hundreds or even thousands of times the mass of the sun). However, this is just a hypothesis. The Fermi Bubbles currently remain a mystery.

 

Visualization of Earth's gravity warping spacetime with a satellite orbiting around it.

What Causes Gravity?

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It may be hard to believe that the cause of gravity continues to remain one of the great mysteries of science, even to this day. This article will briefly explore our understanding of gravity.

We are all familiar with the effects of gravity. The story of Newton being hit on the head by an apple leading to his discovery of gravity is often taught to school children. In short, gravity is a natural phenomenon by which all physical bodies attract each other. For example, the Earth attracts you and keeps you grounded. When you weigh yourself, you are actually measuring the effect gravity has on your body. Although this seems obvious, science still continues to debate what causes gravity.

In 1687, English mathematician Sir Isaac Newton published Principia and wrote, “ “I deduced that the forces which keep the planets in their orbs must [be] reciprocally as the squares of their distances from the centers about which they revolve: and thereby compared the force requisite to keep the Moon in her Orb with the force of gravity at the surface of the Earth; and found them answer pretty nearly.” This became known as Newton’s inverse square law of gravity. Although Newton was unable to define the exact nature of the gravitational force, Newton’s law of universal gravitation became widely accepted right up to the beginning of the 20th century. It is often taught in high school science classes and for most applications is a good approximation regarding the behavior of gravity.

In 1915, Einstein published his theory of gravity within the framework of his now famous theory of general relativity. According to general relativity, the effects of gravitation are caused by a spacetime curvature and not a force, as Newton had asserted.  Einstein’s theory of general relativity was able to successfully account for several effects that were unexplained by Newton’s law, such as the anomalies in the orbits of Mercury. Einstein’s theory of general relativity proposed that spacetime is curved by matter, and that free-falling objects are moving along locally straight paths, called geodesics, in curved spacetime. A simple way to think about this is to think about a drum. Now think about pushing down in the center of the drum. This would cause the entire surface of the drum to become concave (i.e., curve inward). If you drop a marble on the drum, it will fall to the center due to the inward curvature of the drum’s surface. Although Einstein general theory of relativity is now a corner stone of modern physics, especially astrophysics, it still did not explain fundamentally why or how matter curves space, which still left the nature of gravitation a mystery. On a side note, while general relativity predicted numerous phenomena, such as  gravitational lensing (i.e., the bending of light by a large mass) and an effect of gravity on time known as gravitational time dilation (i.e., the slowing down of “clock” in a strong gravitational field), it was incompatible with the highly successful theory of quantum mechanics, which describes the behavior of atoms and subatomic particles.

Where does all this leave us? Currently, there is no widely accepted theory on the fundamental nature of gravity. However, there is no lack of proposed theories. The one that appears to have the most support is string theory. M-theory is the most comprehensive formulation of string theory. In general, M-theory asserts that the fundamental building blocks of all matter can be reduced to infinitely small building blocks of vibrating energy, having only the dimension of length, termed “stings.” Conceptually, the “strings” vibrate in multiple dimensions. The vibration of the string determines whether it appears as matter or energy. According to string theory, every form of matter or energy is the result of the string’s vibration. In addition, M-theory predicts there are eleven dimensions, ten spacial and one temporal, as opposed to the four dimensions implicitly predicted by relativity and quantum mechanics. One of the attractions of string theory is that it fundamentally explains gravity. At this point, you might think we have finally reached a conclusion regarding the nature of gravity, but there are problems. There is no scientific consensus that M-theory correctly describes reality. Its detractors, such as Richard Feynman, Roger Penrose and Sheldon Lee Glashow, have criticized M-theory for not providing experimental predictions at accessible energy scales. In essence, science has been unable to verify M-theory experimentally.

While scientists understand how gravity acts, they do not understand why it exists. For example, why are atoms mostly empty space, instead of being pulled into a solid mass by gravity? Why is the force that holds atoms together different from gravity? Modern physics holds that the gravitational force is mediated by a massless particle called the graviton, which is postulated to travel at the speed of light. However, there is no experimental evidence that the graviton exists. In essence, the effects of gravity have been known for thousands of years, likely by the earliest humans. Laws describing the behavior of gravity have been known for hundreds of years. The exact nature of gravity continues to be controversial. 

A bright sun shining through clouds at the end of a wooden bridge with railings extending into the sky.

Can Science Prove God Exists?

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Is it possible to prove or disprove the existence of God using the natural sciences? This article will examine the evidence, not to prove or disprove God exists, but to address whether it is possible to prove or disprove God exists.

First, we need to start with a definition of God. God means different things to different people, cultures, and civilizations. We likely could fill hundreds of pages, and still not cover all the potential definitions. Therefore, in the interest of brevity and focus, we will not concentrate on the beliefs of any one religion, but rather on the general themes regarding the nature of God that weaves through numerous religions. For this reason, it would be better to not use the word God, since it is often associated with monotheism (one God), but rather the word “deity,” which encompasses polytheism (multiple Gods). The question becomes, what is the nature of a deity? Five key attributes of a deity are found in numerous religions throughout the world:

  1. It is an eternal, divinely simple (no parts), supernatural being (omnipreternatural).
  2. It knows all (omniscience).
  3. Its power is unlimited (omnipotence).
  4. It is everywhere (omnipresence).
  5. It is all good (omnibenevolence).

If we attempt to go beyond the five attributes described above, we inevitably get into specific religions. However, the five attributes are sufficient to make one pivotal point, namely that a deity is supernatural. What would this imply? It implies that a deity is beyond the realm of nature (physical reality). Therefore, any experiments we do in the physical world will give us physical data, not supernatural data. This is a critical point; it implies that scientific proof of the existence of a supernatural being is impossible. The reverse is true. It implies it is impossible to disprove the existence of a supernatural being. We could stop here because the objective was to answer the question: is it possible to prove or disprove the existence of God using the natural sciences? If you assume God is supernatural, item 1, using the natural sciences to prove or disprove God’s existence would appear futile.

Unfortunately, I think most scientists and lay people that attempt to prove or disprove the existence of God really don’t get this crucial point, but use natural evidence to make inferences. Let me frame the debate. From a historical broad-brush perspective, it comes down to two main camps:

  1. Evolutionism—asserts we are here because of evolution, not divine intervention. In a modern context, the evolution is viewed to have started with the Big Bang itself. This school has also been termed “Darwinian evolution” and “scientism.”
  2. Creationism—asserts we are here because of divine intervention, referred to as “intelligent design.” In a modern context, the Big Bang was “God’s” chosen method to create our universe, which ultimately resulted in our existence.

Although, both camps make excellent points, and may people are convinced by their logic, they are not strictly scientific proof. Is not possible to prove the existence of a supernatural being (i.e., a being outside the natural laws) using natural laws (i.e., science)? In the end, I judge it comes down to belief, not science. What do you believe?