The Earth's magnetic poles flip every few hundred thousand years. The last flip was some 780,000 years ago (i.e., we are overdue), and an anomaly that precedes and accompanies the magnetic pole flip is occurring now. "When the field flips it also tends to become very weak. What currently has geophysicists...abuzz is the realization that the strength of Earth’s magnetic field has been decreasing for the last 160 years at an alarming rate. " (The Conversation, Feb 17, 2017) The flip does not happen in an instant - it takes 1,000 to 10,000 years to complete.
"Just before a reversal, the extreme weakening of our magnetic field, the shield that protects us from charged particles constantly blasting the atmosphere, could cause trouble. Live Science previously reported these charged solar particles could punch holes in Earth's atmosphere akin to the ozone hole above Antarctica. Whether those holes would have any true impact is debatable, scientists have said. The increased radiation, however, could mess with the navigation of satellites and aircraft as well as electrical power grids." (LiveScience)
So, although we may not be in for a doomsday scenario, when the flip occurs, there will be some effects.
"The second full moon of January passed through Earth's shadow in a Super Blue Blood Moon eclipse today (Jan. 31), a rare lunar sight visible to millions of observers around the world. Today's lunar eclipse was the first to coincide with a Blue Moon – a second full moon in one month – in North America in over 150 years. It was also the second "supermoon" of 2018, with the moon appearing slightly bigger and brighter than usual due to its closeness to Earth. And to top it off, the supermoon passed through Earth's shadow this morning, casting a reddish hue on the lunar surface for more than 4 hours." [Space.com, January 31]
Photo is from Space.com article. Astrophotographer James Jordan captured this view of the Super Blue Blood Moon at totality from Oakland, California. Credit: James Jordan
POSTED MARCH 18, 2018
"Scientists say they have observed a signature on the sky from the very first stars to shine in the Universe. They did it with the aid of a small radio telescope in the Australian outback that was tuned to detect the earliest ever evidence for hydrogen. This hydrogen was in a state that could only be explained if it had been touched by the intense light of stars. The team puts the time of this interaction at a mere 180 million years after the Big Bang. Given that the cosmos is roughly 13.8 billion years old, it means the first stars lit up a full nine billion years before even our own Sun flickered into life. Dr Judd Bowman of Arizona State University, US, is the lead author on the scholarly paper describing the observation in the journal Nature.
"The...observation may [also] be the first hint that ...interactions [of ordinary matter with dark matter] are possible and the news therefore is likely to galvanise efforts to make the first detections of dark matter particles. "
(BBC, 2/28/2018)
Murchison Australia radio spectrometer (CSIRO Australia)
POSTED APRIL 18, 2018
POSTED 5/29/2018
"Lava is reaching the ocean and building land while producing spectacular plumes of steam. These eruptions are hugely important for the creation of new land. But they are also dangerous. Where the lava meets the ocean, corrosive acid mist is produced and glass particles are shattered and flung into the air. Volcanic explosions can also hurl lava blocks hundreds of meters and produce waves of scalding hot water.
"At Kīlauea, lava is erupting from a line of vents on the volcano’s flanks, and is moving downslope to the edge of the island, where it enters the ocean. This is a process that has been witnessed many times at Hawai’i and other volcanic islands. And it is through many thousands of such eruptions that volcanic islands like Hawai’i form."(Popular Science, May 24)
Photo is from EPA and appears in the May 24 Popular Science article.
POSTED SEPTEMBER 12, 2018
Right: Artist impression of an outflow of molecular gas from an active star-forming galaxy.
Credit: NRAO/AUI/NSF, D. Berry
POSTED OCTOBER 4, 2018
Image is from the phys.org article
The distribution of dark matter (colored in blue) in six galaxy clusters, mapped from the visible-light images from the Hubble Space Telescope. (Source: NASA, ESA, STScI, and CXC) Credit: NASA, ESA, STScI, and CXC
*"Physicists, to date, know of only four basic forces of nature. The electromagnetic force allows for vision and mobile phone calls... Without the so-called strong force, the innards of atoms would fall apart. The weak force operates in radiation, and gravity – the most pervasive of nature's forces."
By Ann Feild (STScI) - http://hubblesite.org/newscenter/archive/releases/2001/09/image/g/
POSTED NOV 2, 2018
More on supernovae and the elements:
What Is a Supernova? How elements are formed
POSTED JANUARY 6, 2019
Scandium or Sc (21) — TVs and energy-saving lamps.
Yttrium or Y (39) — cancer drugs, rheumatoid arthritis medications, and surgical supplies; superconductors and lasers.
Lanthanum or La (57) — Lanthanum finds use in camera/telescope lenses, special optical glasses, and infrared absorbing glass.
Cerium or Ce (58) — Cerium is found in catalytic converters, and is used for precision glass-polishing. It's also found in alloys, magnets, electrodes, and carbon-arc lighting.
Praseodymium or Pr (59) — This is used in magnets and high-strength metals.
Neodymium or Nd (60) — Many of the magnets around you have neodymium in them: speakers and headphones, microphones, computer storage, and magnets in your car. The mineral is especially important for green tech batteries (for electric cars and wind turbines).
POSTED JULY 22, 2019
*For more details on the Sakharov conditions, see the Wikipedia entry for baryon asymmetry.
**Spin is a property of elementary particles related to the magnetic field generated as the particle moves.
Baryon - a subatomic particle that has a mass equal to or greater than a proton
Big Bang Theory - the universe started with an infinitely small, infinitely dense, gravitational singularity containing all the mass and space-time of the Universe which then expanded over the next 13.77 billion years to the cosmos of today. (Graphic left)
Cosmic Inflation, or inflation - theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10−36 seconds after the conjectured Big Bang singularity to some time between 10−33 and 10−32 seconds after the singularity. Following the inflationary period, the universe continues to expand, but at a less rapid rate
Gravitational waves are disturbances in the curvature of spacetime, generated by accelerated masses, that propagate as waves outward from their source at the speed of light. These 'ripples' in space-time are caused by some of the most violent and energetic processes in the Universe. Albert Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity. Einstein's mathematics showed that massive accelerating objects would disrupt space-time in such a way that 'waves' of distorted space would radiate from the source (like the movement of waves away from a stone thrown into a pond).
A quantum fluctuation is the temporary change in the amount of energy in a point in space, as explained in Heisenberg's uncertainty principle. This allows the creation of particle-antiparticle pairs of virtual particles. Quantum fluctuations may have been necessary in the origin of the structure of the universe: according to the model of expansive inflation the ones that existed when inflation began were amplified and formed the seed of all current observed structure.
Left: Andrei Sakharov was "one of the main players in the Russian nuclear arms program.. often called the father of the Soviet hydrogen bomb. But he later renounced the proliferation of nuclear arms and became an international voice of pacifism and defender of human rights in the Soviet Union, earning him the [1975] Nobel Peace Prize." - Stephon Alexander, The Jazz of Physics
Sakharov was not allowed to leave the Soviet Union to collect the prize. His wife Yelena Bonner read his speech at the ceremony in Oslo, Norway. Titled "Peace, Progress, Human Rights", Sakharov called for an end to the arms race, greater respect for the environment, international cooperation, and universal respect for human rights. He included a list of prisoners of conscience and political prisoners in the USSR, stating that he shares the prize with them. By 1976 the head of the KGB Yuri Andropov was prepared to call Sakharov "Domestic Enemy Number One". ..Sakharov was arrested on 22 January 1980, following his public protests against the Soviet intervention in Afghanistan in 1979, and was sent to the city of Gorky, now Nizhny Novgorod. Between 1980 and 1986, Sakharov was kept under Soviet police surveillance and their apartment in Gorky was repeatedly subjected to searches and heists. (Wikipedia)
1964 - CMB radiation discovered
1967 - Sakharov's three conditions
1980 - Guth seminar on cosmic inflation
1998 - dark energy discovered; used to explain the current accelerating expansion of the universe
2001 - WMAP launched
2015 - first direct observation of gravitational waves
ORIGINALLY POSTED AS PART OF "Cosmic expansion (11 bya), complex life (3 bya), Ebola drugs (2019)" - Aug 15, 2019
"A trio of articles in the journal Nature provides us with encouraging news about both the quest to understand the nature of the universe and the attempt to halt a deadly disease. The resource-intensive multinational galaxy mapping, the 12 year effort by a group of dedicated biologists to isolate an "oddball" microbe, and a successful clinical trial in the midst of the second deadliest Ebola outbreak in history remind us of what humanity at its best can accomplish."
Image of cosmological red shift is from Socratic.org.
Light spectra and red shift
Astronomers use light spectra to determine the composition of stars. From the dark absorption lines and bands, they can determine the elemental composition of the star. The red shift - the absorption lines moving towards the red end of the spectrum -indicate an object is moving away from us because it has a longer wavelength.
POSTED OCT 23, 2019
CMB radiation, the "afterglow" of the Big Bang: While a young researcher at Princeton, at a time when the Big Bang had not yet been fully accepted, he was part of Professor Robert Dicke's team. The team was working on the theory that "if the universe was expanding, then it must have been much smaller, hotter and denser in the past. The prediction was that the thermal radiation from this epoch might still be observable today as background radiation pervading the universe." [2] When Penzias and Wilson, working at Bell Labs, came to Princeton to consult on some anomalous results, the Princeton group realized that this was indeed the afterglow of the Big Bang that they had predicted. In 1965, Peebles, Dicke and two colleagues "laid out the basic explanation of what the CMB is and how it relates to the Big Bang. They argued that the light had propagated through space almost since the beginning, growing fainter and less energetic over time as the expansion of space stretched it out. From the energy of these photons today, they could infer an early-universe temperature of more than 10 billion degrees Celsius." [1]
Dark matter: In 1966, Peebles made detailed calculations of the "abundances of different isotopes that would have been produced in this process...However, this CMB-based estimate differed from what astronomers have observed in the present-day universe. The discrepancy indicated that crucial ingredients might have been missing. As both theory and observation of the CMB improved, Peebles and other theorists grew confident that the early density of protons and neutrons paled next to that of a different kind of matter, now known as dark matter, that did not readily interact except through gravity." [1]
Structure of the universe: In the 1970s, he pioneered the theory of cosmic structure formation, which describes how the subtle hot spots and cold spots seen in the CMB evolved into the galaxies and voids in the present-day universe.
[1] Quanta Magazine
[2] Scroll.in
The astronomers Michel Mayor and Didier Queloz won half of the prize for their 1995 discovery of a Jupiter-like planet orbiting a nearby star. The cosmologist James Peebles won the other half for work exploring the structure of the universe.
POSTED NOVEMBER 22, 2019
*Giovanni Domenico Cassini was an Italian mathematician, astronomer and engineer. Known for his work in the fields of astronomy and engineering, Cassini discovered four satellites of the planet Saturn and noted the division of the rings of Saturn.
Saturn's polar hexagon and hurricane
Saturn has a hexagonal storm that rages continuously around its north pole. A consequence of fluid dynamics and Saturn's chaotic but rapidly-rotating atmosphere, this is the first such storm ever discovered on a gaseous world. Over 32,000 km (20,000 miles) wide, the storm starts at 78º latitude and extends down for some 100 km (60 miles). (Forbes)
Making icy moons look more habitable than ever
Cassini found evidence of subsurface oceans of liquid water on some of the moons, spotted geysers and other geologic activity, and even found indications of prebiotic chemistry. Based on Cassini's findings, scientists think the Saturn system is home to multiple moons that could be hospitable to life. The science revealed by Cassini will also help scientists search for life in other solar systems. (Space.com)
"Early-Earth-like" Titan, dynamic and active rings
ESA’s Huygens probe parachuted to Titan, making the first landing on a moon in the outer solar system
Found Saturn’s rings to be active and dynamic — a laboratory for how planets or moons form
Revealed Titan to have rain, rivers, lakes and seas; it is shrouded in a thick, nitrogen-rich atmosphere that might be similar to what Earth’s was like long ago (NASA)
POSTED DECEMBER 7, 2019
37 scientists from 8 countries
Using astro-seismology to determine the age of stars
The Kepler telescope "was so sensitive it would have been able to detect the dimming of a car headlight as a flea walked across it."
In 2013, however, Kepler "broke down, and NASA reprogrammed it to continue working on a reduced capacity." This allowed for a fresh analysis of data.
The confusion from the original data (younger stars in the older portion of the Milky Way) was not a problem of data but of the modelling
POSTED APRIL 29, 2020
When the American astronomer Edwin Hubble was studying the spectra of distant galaxies in the 1920's, he observed a red shift - a shift of the spectral lines towards longer red wavelengths - which could only be explained by these galaxies moving away from us. In 1929, he announced that almost all galaxies appeared to be moving away from us. In fact, he found that the universe itself was expanding with all of the galaxies moving away from each other. His estimate of the rate of expansion was considerably off, but his discovery of the expanding nature of the universe paved the way for the Big Bang Theory, the leading theory about how the universe began.
Since Hubble's discovery, scientists have been attempting to calculate the rate of the universe's expansion. Knowing the rate of expansion would, among other things, allow an estimation of the age of the universe. For many years, astronomers and others believed they knew the answer: the universe was expanding at a constant rate that indicated its age to be estimated as 13.8 billion years.
Then in 2016, NASA and the European Space Agency jointly announced that the universe is expanding up to 9% faster than predicted, a finding they reached after using the Hubble space telescope to measure the distance to stars in 19 galaxies "just" beyond the Milky Way. Based on observations of cosmic background radiation, the "Hubble constant" appeared to have a value of 73.4 kilometers per second per megaparsec. In 2018, another team using the Planck telescope to study the cosmic microwave background - the leftover radiation from the Big Bang - predicted a value of 67.4. Both teams have made increasingly accurate estimates, but the difference between the "local" team and the "Planck team" has not grown any smaller. In other words, the universe appears to be expanding faster now than it did in the early universe.
The question that scientists are grappling with is "Why?" And the reason this is important goes beyond estimating the age of the universe and its ultimate fate. The Standard Model of particle physics, which has successfully explained almost all experimental results and precisely predicted a wide variety of phenomena since the 1970's, may be missing something. The last time our concept of the basic building blocks of matter and energy was upset was in 1998 with the discovery of dark energy.
Quanta magazine discusses some of the current theories (link below right): "Because so little is known about [dark matter and dark energy], they are perhaps the obvious place to begin tampering with the standard model." The challenge is to change the standard model"without ruining the model’s perfect fit with a wealth of other astronomical observations."
Some of the "tampering" with the Standard Model considered in the Quanta article:
"A form of dark matter that decays into a lighter particle and a massless particle known as a dark photon. As more and more dark matter decayed over time, its gravitational pull would have lessened, and thus the expansion of the universe would have sped up."
"An extra dose of dark energy in the early universe, dubbed early dark energy, could reconcile the conflicting values of the Hubble constant."
"A modified-gravity model that was capable of behaving as if there were extra radiation in the early universe; the radiation pressure would have increased the cosmic expansion rate."
So much progress in understanding the universe had been made in the 20th century that, around 1980, Stephen Hawking, the great cosmologist, predicted the end of theoretical physics within 20 years. Around 2001, he amended his prediction to twenty years more from that year. If discoveries such as the varying rate of expansion of the universe are an indication, we may have several additional 20 year periods to go.
POSTED MAY 25, 2020
The leading theory for star and planet formation goes something like this: A disturbance - perhaps from a nearby supernova explosion or a passing star - causes a pressure change in the loose collection of interstellar gas and dust called a nebula. The nebular cloud of gas and dust collapses into a disc. The center of this disc sees a great increase in pressure and hydrogen atoms begin to come into contact. Eventually, they fuse and produce helium, starting the formation of a star. The newly formed star scoops up nearly all the material in the collapsing cloud. Gravity and other forces cause the remaining material within the disk to collide and clump together. In time, these small grains of dust continue to collide and grow from the width of a human hair to pebbles to mile-sized rocks to eventually planets. A video showing how the solar system might have formed is in the sidebar.
Scientists using the Very Large Telescope in Chile to observe AB Aurigae, a star located 520 light years from Earth, have found the first direct evidence of the birth of a planet. Vice [link below] describes their observation as "a baby picture like no other: A maelstrom of gas and dust swirling around what is likely a newborn giant planet. This stunning portrait is a composite that could be the first direct evidence of the hellacious site of a planet’s birth, according to a study published on Wednesday [May 20] in Astronomy & Astrophysics."
POSTED OCTOBER 23, 2020
For centuries scientists, philosophers, and science fiction writers suspected that extrasolar planets existed, but there was no way of knowing whether they existed, how common they were, or how similar they might be to the planets of the Solar System. In the sixteenth century, the Italian philosopher Giordano Bruno, an early supporter of the Copernican theory that Earth and other planets orbit the Sun (heliocentrism), put forward the view that the fixed stars are similar to the Sun and are likewise accompanied by planets. In the eighteenth century, the same possibility was mentioned by Isaac Newton in his Principia. Making a comparison to the Sun's planets, he wrote "And if the fixed stars are the centres of similar systems, they will all be constructed according to a similar design and subject to the dominion of One." [1]
It wasn't until the late 20th century however that scientists had the tools to prove these early speculations correct. The first suspected scientific detection of an exoplanet, a planet outside the solar system, occurred in 1988. Shortly afterwards, the first confirmation of detection came in 1992, with the discovery of several terrestrial-mass planets orbiting a pulsar 2300 light years away.
The search for exoplanets took an exponential leap in 2009 with the launch of NASA's Kepler Space Telescope. Kepler was designed to survey a portion of Earth's region of the Milky Way to discover Earth-size exoplanets in or near habitable zones and estimate how many of the billions of stars in the Milky Way have such planets. Kepler used photometry to monitor the brightness of approximately 150,000 stars. These data were transmitted to Earth, then analyzed to detect periodic dimming caused by exoplanets that cross in front of their host star. During its over nine and a half years of service, Kepler observed 530,506 stars and detected 2,662 planets. [1]
When Kepler was retired after running out of fuel, TESS took its place. TESS launched April 18, 2018 aboard a SpaceX Falcon 9 rocket. NASA’s Transiting Exoplanet Survey Satellite (TESS) is an "all-sky" survey mission - covering a sky area 400 times larger than that monitored by Kepler. The stars TESS studies are 30 to 100 times brighter than those the Kepler mission surveyed, which will enable easier follow-up observations with both ground-based and space-based telescopes. [2]
As of October 22, 2020, Kepler and TESS had identified a total of 4296 exoplanets [link sidebar], many of the them in the habitable zone and many of them "Earth-like". A planet being in the habitable zone does not mean that life actually exists there, just that it has conditions that would allow life to exist.
It may also be possible that there are “superhabitable planets” in the cosmos where the chances for life to develop are even higher. In a recent analysis published in the journal Astrobiology, a research team led by astrobiologist Dirk Schulze-Makuch from the Technical University Berlin says we might have already detected 24 of them. The researchers propose that the search for extraterrestrial life “might be executed most effectively with a focus on superhabitable planets instead of Earth-like planets”. [3]
Schulze-Makuch’s team outlines several criteria that might help spot a superhabitable planet [4]:
A hot, humid planet could be more biologically productive, since Earth’s tropical regions contain its most biodiverse habitats.
Planets that are about 1.5 times as massive as Earth might be especially conducive to biodiversity because they would have more surface area, and would also be more likely to form a thick protective atmosphere.
A planet’s host star is another important factor in its habitability. Our Sun, a yellow dwarf star, may not be the most optimal type of star in superhabitability assessments because of its relatively short lifespan. The stellar sweet spot, according to Schulze-Makuch’s team, is the orange dwarf star. These stars are smaller than the Sun, larger than red dwarfs, and could live for 20 to 70 billion years, extending the timeline for life to emerge.
The team emphasized that data about exoplanets are still extremely limited: “Some of the astrophysical conditions that we identify as crucial for a planet to be potentially superhabitable are far from being observationally testable on planets outside the solar system.” Nevertheless, the new study offers a comprehensive roadmap for follow-up studies aimed at certain targets. Sophisticated new observatories, such as NASA’s James Webb Space Telescope, might eventually be able to pick out signs of life, known as biosignatures, in these worlds. [4]
[1] Wikipedia [2] NASA [3] Extreme Tech [4] VICE
Biosignature -any substance or phenomenon that provides scientific evidence of past or present life. Measurable attributes of life include its complex physical or chemical structures and the production of biomass and wastes.
Habitable zone - the area around a star where it is not too hot and not too cold for liquid water to exist on the surface of surrounding planets. Sometimes referred to as the "Goldilocks" zone. Life began in water on Earth and is a necessary ingredient for life as we know it.
Neutron star - the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses.
Photometry - the science of the measurement of light, in terms of its perceived brightness to the human eye
Pulsar - a neutron star that emits beams of radiation that sweep through Earth's line of sight. Like a black hole, it is an endpoint to stellar evolution. The "pulses" of high-energy radiation we see from a pulsar are due to a misalignment of the neutron star's rotation axis and its magnetic axis.
POSTED DECEMBER 20, 2020
If you look to the southwest near the horizon an hour after sunset on December 21st, you may be able to see the "Christmas Star". Jupiter and Saturn will put on a show that hasn't been seen in almost 800 years. Astronomers are calling it the Great Conjunction* of 2020. The two largest planets in our solar system will appear to almost merge in Earth’s night sky.
For centuries, scholars have speculated about what "The Star of Bethlehem" in the Gospel of Matthew might have been. Meteor, supernova, comet and planetary conjunction have all been put forward as possibilities. It is unlikely that the Star was a meteor, since meteors burn up in a matter of minutes. The only supernova that was visible from Earth around the time of Christ's birth actually happened in the year 185 A.D. and was recorded by Chinese astronomers . In the year 5 B.C., Chinese astronomers also noted the appearance of a “Broom Star” that many researchers have interpreted as a comet. In ancient times, though, comets were usually interpreted as bringers of bad news, not as the coming of the Messiah.
So that leaves us with planetary conjunctions. When the motion of the planets is rewound with observing software, astronomers found that several interesting conjunctions played out in the years around the life of Jesus. In the year 7 B.C., Jupiter and Saturn had three conjunctions in the same constellation, Pisces. So, if Jupiter and Saturn had three close conjunctions in a relatively brief period of time, it’s easy to imagine that ancient astronomers would have taken note, and they also likely would have ascribed some meaning to the event.
Whether a planetary conjunction explains the Star of Bethlehem or not, we will have a rare conjunction of Jupiter and Saturn in the hours just after sunset on the day of the winter solstice.
Lowell Observatory in Arizona will be live streaming the event starting at 5 pm MST/7 pm EST. Astronomy.com has a link to the live stream here.
*A conjunction happens when two celestial objects appear to pass close to one another as seen from Earth. The objects are actually many millions of miles apart but from Earth they appear next to one another. Conjunctions occur frequently but a conjunction of two bright planets like Jupiter and Saturn is rare.
Sources: The Star of Bethlehem: Can Science Explain What It Really Was? (astronomy.com) ; Jupiter and Saturn will form rare "Christmas Star" on winter solstice (astronomy.com)
POSTED DECEMBER 31, 2020
The global effort to understand and stop the novel coronavirus was, by far, the most important scientific effort this year. More than 1.8 million confirmed deaths have been reported. Vaccines have been developed in record time. Here in the US, racial, social and healthcare inequities led to a gross disparity in the mortality rates between whites and people of color.
Beyond the coronavirus, researchers made important discoveries and increased understanding of our world. Here are a few of them.
Despite the temporary downward blip caused by coronavirus lockdowns, climate change intensified. Though 2020’s emissions will drop by 4-7% as compared to 2019’s, atmospheric carbon dioxide levels will increase, the World Meteorological Organization found. Massive wildfires devastated forests in Australia, the Amazon, California and Colorado. The Atlantic hurricane season was the most severe ever recorded.
"NASA’s OSIRIS-REx and the Japan Space Agency’s Hayabusa2 space missions set out to sample rock, dirt, and debris from space rocks. On Oct. 20, the OSIRIS-REx probe successfully touched down on the surface of Bennu, a space rock about 200 million miles from Earth. On Dec. 8, the Hayabusa2 spacecraft returned a sample from Ryugu, an asteroid 180 million miles away, to Earth...Scientists suspect that when asteroids like Ryugu and Bennu pummeled a proto-Earth billions of years ago, they may have helped kick-start life by delivering the necessary building blocks." [1]
Three long-planned Mars missions got off the ground. The latest US rover, and orbiters designed by China and the United Arab Emirates launched in late July. The latest US rover Perseverance will do things no Mars rover has ever done — hunt for signs of life, collect samples for future return to Earth and deploy a miniature helicopter, to name a few. The UAE mission will focus on understanding Mars' weather and atmosphere while China's Tianen-1's scientific objectives include Mars' geology, surface soil and water-ice, ionosphere, electromagnetic fiels and surface climate.
75 years after the atomic bombing of Japan in August 1945, a new international treaty on the prohibition of nuclear weapons is on the table. The new agreement, the Treaty on the Prohibition of Nuclear Weapons (TPNW), is expected to become international law next year once 50 nations haqve signed it. The treaty would make it difficult for individuals (including scientists), as well as companies (including banks), from the treaty’s member countries to play any part in the development and deployment of nuclear-weapons technologies.
Researchers found that even the dendritic arms of neurons in the brain seem capable of processing information, which means that every neuron might be more like a small computer by itself. The analogy to computers is important for AI: "when artificial neural networks capable of “deep learning” tackle problems of perception, the ones that work best have organizational structures remarkably similar to those of the living brain. Both types of systems seem to converge on the same computational solutions, which may mean that deep networks could be increasingly useful tools for deciphering the brain’s secrets." [2]
New precise data from the ESA's Gaia spacecraft has confirmed that the universe is expanding faster than predicted by the standard model of cosmology. In a paper published earlier this month, a research team confirmed an expansion rate of 73.2 kilometers per second per megaparsec, in line with their previous value, but now with a margin of error of just 1.8%. That seemingly cements the discrepancy with the far lower rate of 67 obtained from the standard model of cosmology. [3] The faster than predicted expansion rate points to an unknown in the standard model, which has accurately predicted findings for decades. Astrophysicists are searching for answers as the so-called "Hubble crisis" worsens.
References: [1] PBS/NOVA [2] Quanta Magazine [3] Quanta Magazine
Below: links from PBS (left) and The Smithsonian (right).
POSTED JANUARY 26, 2021
About 13.8 billion years ago, an infinite concentration of energy in an infinitely small space exploded, and our universe of matter, energy, space and time began. The Big Bang Theory is the leading explanation about how it all started. At its simplest, it says the universe as we know it started with a small singularity, then inflated over the next 13.8 billion years to the cosmos that we know today. [sidebar]
For the first 10^-43 seconds of expansion, this density of energy was so extreme physics can't yet provide a clear description of what was happening. [1] Rewinding the expansion of the universe to the Big Bang singularity - this extremely small, massively dense speck of heat and energy - the laws of physics and time as we know them cease to function.
What happened before the Big Bang is speculative, but extrapolating from our current understanding of the universe and the mathematics that explains it, here are some of the theories.
Stephen Hawking's answer to the question "What was there before there was anything?" relies on a theory known as the "no-boundary proposal." Time as we understand it literally did not exist before the universe started to expand. Rather, the arrow of time shrinks infinitely as the universe becomes smaller and smaller, never reaching a clear starting point. Essentially "there was never a Big Bang that produced something from nothing. It just seemed that way from mankind's perspective." [2]
Cal Tech theoretical physicists Sean Carroll and Jennifer Chen have suggested that the universe as we know it is the offspring of a parent universe from which a bit of space-time has ripped off. It's like a radioactive nucleus decaying. "When a nucleus decays, it spits out an alpha or beta particle. The parent universe could do the same thing, except instead of particles, it spits out baby universes, perhaps infinitely. 'It's just a quantum fluctuation that lets it happen,' Carroll said. These baby universes are 'literally parallel universes' and don't interact with or influence one another." [3]
The universe was an "infinite stretch of an ultrahot, dense material, persisting in a steady state until, for some reason, the Big Bang occurred. This extra-dense universe may have been governed by quantum mechanics, the physics of the extremely small scale...The Big Bang, then, would have represented the moment that classical physics took over as the major driver of the universe's evolution." [3]
"Prior to the Big Bang, there was another universe, identical to this one but with entropy increasing toward the past instead of toward the future. Increasing entropy, or increasing disorder in a system, is essentially the arrow of time...so in this mirror universe, time would run opposite to time in the modern universe and our universe would be in the past" [3] [For more on entropy and the arrow of time see the Royal Institution's video in the sidebar]
The "Big Bounce" in which "our big bang" is just one in an infinitely long series of expansions and contractions. Developed from string theory [see sidebar] the "Big Bounce" proposes that this "cyclic universe goes about exactly as you might imagine, continually bouncing between big bangs and big crunches, potentially for eternity back in time and for eternity into the future." [4]
Theoretical physicist Brian Greene discusses these theories in an interview with Joe Rogan. [sidebar]
POSTED SEPTEMBER 9, 2021
Since the late 19th century, physicists and science wags have been predicting the imminent end of theoretical physics. Mankind would soon know all there is to know about the physical universe and need not look further. 150 years later, the end of physics is nowhere in sight. Like an infinitely-nesting Russian doll, as one mystery is resolved, another comes into view.
In the twentieth century, we learned that energy and matter were related and interchangeable, that gravity causes space to curve, that the universe exploded into existence from an infinitesimally small point, that the world of the very small was stranger than anything we could ever imagine, that 95% of the matter in our universe cannot be seen, that there exist points of infinite density where matter is swallowed and time stops. And on and on.
So much progress in understanding the universe had been made in the 20th century that, around 1980, Stephen Hawking, the great theoretical physicist and cosmologist, predicted the end of theoretical physics within 20 years. Around 2001, he amended his prediction to twenty years more. It looks like we will have several more 20 year cycles if the early 21st century is any indication.
In the first two decades of this century, we learned that the universe is expanding at faster and faster rates, discovered the Higgs boson - the so-called "God particle" that gives elementary particles their mass, found a supermassive black hole at the center of our Milky Way galaxy, identified the first room temperature superconductor, observed gravitational waves predicted by Einstein in 1916, and produced the first ever image of a black hole using a "telescope" the size of planet Earth.
The Event Horizon Telescope, a planet-scale array of eight ground-based radio telescopes forged through international collaboration, captured this image of the supermassive black hole in the center of the galaxy M87 and its shadow. (Image credit: EHT Collaboration) [4]
Still, mysteries remain...how does the Higgs boson give elementary particles different masses? what is causing the ever-increasing rate of expansion of the universe? do dark energy and dark matter obey the same laws of physics as "normal" matter? and what's up with the 1.8 billion-light-year-spanning "cold spot" in the constellation of Eridanus which looks like a giant bite taken out of the universe?
Speculation on the last item - the 1.8 billion light year supervoid in Eridanus is running rampant: "Could it be a blemish left by another universe bumping into our own? Might it be a portal into a region beyond the known universe? Or some sort of matter-destroying 'bubble'?"
Which brings us (finally) to the subject of this post - the multiverse.
What we call our universe - what we can see out to 14 billion years or so in all directions - may not be unique. There may have been more than one Big Bang, producing universes with different physical laws than our own. This is not just wild speculation. The existence of a multiverse, an "entire ensemble of innumerable regions of disconnected space-time", is one of the consequences of Andrei Linde's theory of eternal chaotic inflation.
But I am getting ahead of myself. Let's step back to see how Linde came to develop his theory.
The Big Bang, the creation of our universe 13.77 billion years ago from a singularity of immense energy, is one of the most widely held theories in all of physics. Originally proposed in 1927 by the Belgian cosmologist and Catholic priest Georges Lemaître, it became the go-to explanation for how the universe began when two engineers at Bell Labs accidentally discovered the Cosmic Microwave Background, a remnant from a very early stage of the universe, in 1964. According to the theory, the Big Bang explosion stretched the very fabric of spacetime, sending superheated matter in all directions. As it expanded, the matter cooled and started to aggregate, forming atoms, then elements, then stars, galaxies and, ultimately, all we know and see today. [1]
In 1981, seventeen years after Penzias and Wilson's discovery, while attempting to answer some of the baffling questions about the observable universe and the Big Bang*, astrophysicist Alan Guth proposed the theory of cosmic inflation. The term refers to the explosively rapid expansion of space-time that occurred a tiny fraction of a second after the Big Bang. In another tiny fraction of a second. the expansion slowed to its current rate. According to Guth's theory, for less than a millionth of a trillionth of a trillionth of a second after the universe's birth, an exotic form of matter exerted a counterintuitive force: gravitational repulsion. Although we normally think of gravity as being attractive (picture Isaac Newton and the falling apple), Albert Einstein’s theory of general relativity allows for such a force. Under the conditions present in the early universe, when temperatures were extraordinarily high, Guth says the existence of this material was reasonably likely. “It only has to be a speck**,” he says. “But when that speck starts to inflate, the expansion is exponential.” [1,2]
Inflation answers many of the unresolved questions of the Big Bang and predicts the observable universe. In 1986, Guth's co-Nobel Prize winner Andrei Linde took cosmic inflation a step further. Linde explains his theory of “eternal chaotic inflation” thus: “Instead of a universe with a single law of physics, eternal chaotic inflation predicts a self-reproducing, eternally existing multiverse where all possibilities can be realized.” [3]
Eternal chaotic inflation is also one attempt to answer the questions: what came before the Big Bang? how will the universe end?***
According to Linde’s theory, there has always been a yesterday and there will always be a tomorrow. Our universe grew out of a quantum fluctuation in some pre-existing region of the space-time continuum. “Each particular part of the [multiverse] may stem from a singularity somewhere in the past and it may end up in a singularity somewhere in the future.” [3]
Mind-boggling. Speculative. Yes, and yet lines of corroborating evidence have convinced many cosmologists to such a degree that cosmic inflation and eternal chaotic inflation have become the "standard model" of cosmology. Physicists around the world are working on the theory of an inflationary multiverse consisting of different universes with different laws of physics.
The infinite possibilities opened by Linde's Multiverse Theory suggest that the end of physics will not occur anytime soon.
Notes
*Two of these questions: Why does the visible universe appear flat and largely homogeneous when general relativity suggests that space should be curved? How did the Universe get so big in the time since the Big Bang given the current rate of expansion?"
**According to cosmic inflation theory, a hundred-thousandth of a gram of matter would suffice to create a universe.
***The traditional scenarios for the end of the universe have been a) the universe expands indefinitely until all energy and matter reach a "heat death" with temperatures near absolute zero b) the matter in the universe is so great that it causes a reversal of the expansion, galaxies collapse and the universe ends in a "Big Crunch", a reverse Big Bang c) the expansion of the universe reaches a steady-state, expansion halts but the universe does not end in a Big Crunch. In Linde's theory of eternal chaotic inflation, the incredibly rapid expansion of space-time (inflation) is a continual process with new universes being created all the time. While a given universe such as ours would suffer heat death, the Multiverse itself would never end.
Sources: [1] Scientific American [2] space.com -1 [3] Stanford Magazine [4] space.com - 2