Advanced science, Astrophysics, Cultural, International, Life as it is, Religious, Technical

Dark Matter and Dark Energy – Part II

In the 1st part on this topic the essential attributes of dark matter had been described. Dark matter was necessary in order to hold the basic fabric of galaxies together; otherwise, billions of stars at the edges of the galaxies would experience weaker gravitational pull and could even fall away from the galactic orbits. So, dark matters were invoked to be present all over the galactic system.  In this part, the role of the dark energy will be considered. Dark matter may keep the individual galactic system intact and maintain higher orbital speeds to outlying stars, but then what is giving the Universe impetus to expand?   

The ‘Standard Model’ of the cosmological system predicted that the Universe simply could not exist in a quiescent steady state – it has to be dynamic in nature, meaning it either has to expand or contract. Indeed, in 1929 Edwin Hubble made an astronomical observation and that had become incontrovertible showing that the Universe was actually expanding. That made Einstein to admit that his cosmological constant, Ʌ (lambda) introduced in the general theory of relativity with a particular value to force a steady state condition for the Universe was flawed. For the next 70 years, until 1998, cosmologists implicitly took Ʌ to be zero and the Universe was described as per Einstein’s field equations. Nobody thought of discarding the cosmological constant that Einstein had introduced, albeit mistakenly.

Then in 1998, another even more astounding evidence was produced based on observation using Hubble telescope, when it was shown that light from very distant supernovae was fading away and showing red shifts indicating supernovae were receding and receding at faster rates further they were from the Earth. In other words, there was an accelerated expansion in the Universe. The Universe’s current expansion rate is known as the Hubble constant, H0 which is estimated to be approximately 73.5 km per second per megaparsec. A megaparsec is the distance of 3.26 million light years. As the speed of light is 3×108 m/s or 9.46×1012 km/year, 1 megaparsec then equals to 3.08×1019 km. A galaxy 1 megaparsec away (3.08×1019 km) would recede from Earth at 73.5 km/s; whereas another galaxy 10 times of 1 megaparsec from the Earth would recede at 10 times of 73.5km per sec = 735 km per sec.  That was a shocking result and the cosmologists were taken completely by surprise.  

What is providing this gigantic Universe enough energy to expand and expand at an accelerated rate? Further observations had demonstrated that this accelerated expansion is in fact taking place in the vast extra-galactic spaces. This came to be known as the ‘metric expansion’. There was no evidence or verifiable evidence of expansion within the individual territories of galaxies. It may indeed be argued that if there were any expansion within a galactic system, then stars would move away from each other and even the planets revolving round the stars would recede. For example, Earth would recede from the Sun and that recessive path would look like a spiral trajectory and eventually Earth would secede completely from the Heliosphere! This would be a recipe for a total disaster for the Earth-bound lives like ours and luckily there was no such evidence of recession. 

Expansion of the Universe as per Standard Model

Albert Einstein’s cosmological constant, Ʌ in the general theory of relativity came to the rescue of this paradox of cosmological expansion. Dark energy was invoked to solve this problem. Dark energy is perceived to be the intrinsic energy of the empty space or simply the vacuum energy. It may be pointed out that space is viewed in the general theory of relativity as the product of gravitational field. As there are limitless empty spaces in the cosmological scale, dark energy can also be limitless. Although the precise mechanism of generation of dark energy is unknown, but some of the essential characteristics may be drawn. Dark energy is repulsive in character. Thus, dark energy can be viewed as something that reacts with ordinary matter (baryonic matter) making up the celestial bodies, but in opposite direction to ordinary gravity. Some scientists speculate that dark energy may even be a form of a new type of force – the fifth force – which is as yet unknown. The known four forces are: electromagnetic force, weak nuclear force, strong nuclear force and the gravitational force and the properties of these forces are well known. If indeed the fifth force does come into play, it would offer a situation where gravity and anti-gravity may come to exist in the same Universe. It may be that the attractive gravity exists within the scale of galaxies, whereas repulsive gravity exists in the vast extra-galactic space!  

Taking material accounting of galaxies into consideration, it is estimated that on the basis of mass-energy composition, the Universe is only 4.5% of ordinary matter, 26.1% of dark matter and 69.4% of dark energy. However, this distribution of mass-energy composition in observable celestial bodies and unobservable black holes do not remain fixed or invariant. At the early part of the Universe’s formation, after about 380,000 years following the Big Bang (13.8 billion years ago), the distribution mass and energy was quite different. Ordinary matter was 12% and dark matter was 63% and there was no dark energy, as shown in the Table below. The situation is quite different now and this shows that the Universe is changing or one can say evolving.

Universe’s mass-energy composition

 13.8 billion years agoPresent day (2000 CE)
Dark energy69.4%
Ordinary matter12%4.5%
Dark matter63.0%26.1%

In the Universe, the amount of ordinary matter (baryonic matter) is fixed and as the Universe expands, the average density of ordinary matter in the Universe is continuously diminishing; as density is the amount of material divided by the volume. Similarly, the dark matter density of the Universe is also decreasing as Universe expands. But the dark energy density had been found to remain constant, no matter how much or how fast the Universe expands. It is due to fact that vacuum energy is constantly added (as space has intrinsic vacuum energy) to the pool of dark energy as Universe expands and hence the dark energy density remains constant.

In the metric expansion, the space or more appropriately, spacetime fabric is created extra-galactic. Space is not something which is devoid of other things. Space is the gravitational field. Like electromagnetic field, gravitational field generating space is granular in character. The quantum of space is so incredibly small that we cannot sense them, similar to solid granular atoms we cannot feel. Space granules are literally trillions of times smaller than atoms. Space granules or space quanta are not within the space, space quanta are the space. A new branch of physics, called ‘loop quantum gravity’ shows how space quanta make up the space. When Universe expands, space is produced with spacetime quanta and the intrinsic dark energies increase.

Although the evidence of accelerated expansion of the Universe was baffling, but it was not unexpected. The Universe had undergone very rapid expansion at the early phase of its existence, some 13.8 billion years ago, after that it slowed down for billions of years and then the expansion phase started about four or five billion years ago. When this expansion will stop or even reverse, nobody knows. But it is definite that the Universe as a whole is not static, it is very much dynamic, vibrant and evolving. If anybody says that the Earth, Sun and Moon and even the whole Universe were created by some unknown Creator and then he left the whole thing in a quiescent state, then there is every reason to question such unfounded claims and discard them as totally baseless.  

  • Dr A Rahman MSRP CRadP FNucI
Advanced science, Astrophysics, Cultural, International, Life as it is, Religious

Dark Matter and Dark Energy – Part I

Until about 100 years ago, the prevailing scientific perception was that our universe was eternal, invariant and in quiescent state. But science has progressed tremendously since then and the very perception of Universe had changed significantly. Albert Einstein’s general theory of relativity in 1916 had revolutionised our view of spacetime of the Universe. Following the general theory of relativity, the Russian physicist Alexander Friedmann in 1922 as well as Belgian astronomer Georges Lemaitre in 1927 independently produced solutions to Einstein’s field equations to show that Universe is actually expanding. 

The planet Earth is one of the eight planets orbiting the Sun. The Sun has curbed out a region of space in the sky where its influence is most dominant and that is called the Heliosphere, as shown in the diagram below. This Sun provides us on this planet, Earth with all the energy we need to live and flourish. The distance between the Sun and the Earth is known as one Astronomical Unit (au) and it is estimated that the gravitational field of the Solar system fades away at about 100,000 au (~1.58 light years).

The Sun may seem overpowering to us and indeed it is, but in the wider perspective the Sun is just an average or below average star in our galaxy, the Milky Way. It is estimated that there are around 300 billion stars, yes, 300,000,000,000 stars in an average galaxy and our galaxy is no more than an average galaxy. In a galaxy there are lots of other celestial bodies such as white dwarfs, neutron stars, supernovae, pulsars (pulsating stars), black holes and many more. Our spiral galaxy, the Milky Way, is about 100,000 light years (ly) across, which means that travelling at the speed of light (300,000 km per second) it will take 100,000 years to go from one end of this galaxy to the other end. One may consider that the speed of light is such that it would go round the Earth seven and half times every second! Our nearest galaxy is Andromeda, which is roughly 2.5 million light years away from us and that galaxy is about 220,000 ly across. It is estimated that there are over 100 billion galaxies in the Universe! So, altogether there would be 30 billion trillion stars (like our Sun) in the Universe (=300 billion stars per galaxy x 100 billion galaxies). The extent of the observable Universe is estimated to be about 93 billion light years across following the Wilkinson Microwave Anisotropy Probe (WMAP)! Now you have a feel of the enormity of the Universe! An image of the Universe is shown below.

WMAP – 2010 image of the observable Universe

In 1915-16 when Albert Einstein produced the general theory of relativity, his field equations predicted that the Universe was expanding. But the prevailing scientific perception (as well as theological dictum) was that the Universe was static and in Steady State. So, he introduced arbitrarily (against the grain of the field equations) in 1917 a quantity called the cosmological constant, Ʌ, with a particular value which would block out the expansion of the Universe. The cosmological constant is the energy density of space or vacuum energy. But in 1929 American astronomer, Edwin Hubble made astronomical observations of distant galaxies that showed red shifts, which was an evidence that the Universe was actually expanding, not static. That red shift was shown to be proportional to the distance of that galaxy from Earth (linear redshift-distance relationship). It did turn the whole of prevailing wisdom on its head and Einstein was left deeply embarrassed. He humbly admitted that the introduction of the cosmological constant was the ‘biggest blunder’ of his life. Without this constraining factor, the equations would naturally lead to predictions of an expanding Universe.

The general theory of relativity produced the spacetime continuum. There is no gravitational force of attraction in the conventional sense. The gravitational field is the space. The gravity creates a curvature in space, more like a heavy body when placed in a trampoline would create a dent, which other lighter bodies would roll down in particular trajectories and that is the analogy of gravitational attraction. Within about two months of publication of the general theory of relativity, the German physicist Karl Schwarzschild provided the proof of existence of gravitational sinkholes, now called the black holes, in the Universe. By solving the field equations, he produced a radius, now called the Schwarzschild radius, that defines the boundary of a black hole. A black hole curves the space towards itself so sharply that nothing, not even the light, can escape it once it is within the grip of the black hole and that is why this body is termed as the black hole.

As mentioned above, Universe is truly unimaginably large. The visible part of the Universe contains celestial bodies that are made up of ordinary baryonic matter such as protons and neutrons, and non-baryonic matter such as electrons, neutrinos etc. For each one of these ordinary matters, there are corresponding anti-matters. For example, there are anti-protons, anti-neutrons, anti-electrons etc. The sinister attribute of these ordinary matters and anti-matters is that when they happen to come in contact with each other, they annihilate each other in a flash and an equivalent amount of energy is created as per Einstein’s mass-energy equivalence equation. Since we are in this ordinary world, there may be anti-world somewhere, made up of anti-matter. But we must never meet each other. If we do, we will end up in a flash into an enormous bundle of energy – creating billions and trillions of times more energy than the Sun.  

In our visible Universe containing billions of galaxies and each galaxy containing billions of stars, it is estimated that there are also a large number of black holes hidden in each galaxy. Black holes exert tremendous amount of gravitational pull to keep billions of stars within the galaxy together. But there is a physical dilemma. If black holes are situated nearer the central core of the galaxy where most of the turbulent celestial activities are taking place, then what is keeping the outlying stars in place where the gravitational pull is much weaker? Still, it had been found that even the remotest of the stars have the same orbital motion as the ones nearer the centre. How do those stars get sufficient gravitational pull to have same orbital motions? To resolve this dilemma, astrophysicists and cosmologists came up with the solution that there must be large amounts of unseen matter dotted all over the galaxies which exert gravitational pull to the stars to have similar orbital motion! This unseen matter is called the dark matter.

There are similarities and dissimilarities between ordinary matter and dark matter. Whereas ordinary matter interacts with light, or generally speaking with electromagnetic energies, dark matter does not. Light goes straight through the dark matter. But it has gravitational pull exactly like the ordinary matter. Although unseen by modern scientific devices, dark matter can be detected by its gravitational fingerprint. Dark matter keeps the fabric of the galaxy intact.

What is this dark matter and what are their constituents, the modern physics has no clue. It cannot be made up of baryonic matters, meaning ordinary protons and neutrons. If they were, they would react to light energy, but they do not. It is speculated that it could be made up of esoteric constituents such as axions, Weakly Interacting Massive Particles (WIMPs), Gravitationally Interacting Massive Particles (GIMPs), supersymmetric particles etc. These are pure speculations. Also, as dark matter and dark energy together comprise 95.5 per cent of Universe’ all mass-energy composition, they may be coupled or tangled quantum mechanically! 

The next article will deal with the dark energy and why dark energy is needed to have the expansion and accelerated expansion of the Universe that is taking place at the moment. In fact, without the dark energy the Universe might have collapsed under its own gravitational pull or might not even have come into existence in the first place.

Dr A Rahman MSRP CRadP FNucI

Advanced science, Bangladesh, Cultural, International, Life as it is, Literary, Technical

Tagore’s philosophical views and Quantum Mechanics

Rabindranath Tagore (actual Bengali name: Rabindranath Thakur) (1861–1941), the great Indian philosopher, a Bengali poet and a polymath, who received Nobel Prize for Literature in 1913, lived during a transition period of Indian history in general and the Bengali culture in particular, when physics also went through revolutionary changes. Albert Einstein (1879–1955), the most prominent physicist of the 20th century, was the pioneer of modern physics, who produced theories which advanced physics to unprecedented levels. Although Einstein produced the ‘the principle of photoelectric effect’ for which he received the Nobel Prize for physics in 1921 and which was pivotal to the advent of quantum mechanics, he could not fully reconcile with the multifarious implications of quantum mechanics. The two stalwarts of the first half of the 20th century met a number of times from 1926 onwards. When Tagore visited continental Europe and then America in 1930, they met at least four times in Berlin and New York. The meeting at Einstein’s summer villa outside Berlin was of particular interest when they exchanged views and philosophical ideas extensively. During that meeting – poignantly described by Dmitri Marianoff, a journalist in the New York Times, as being between ‘Tagore, the poet with the head of a thinker, and Einstein, the thinker with the head of a poet’ – the two exchanged views on the reality of nature.

Einstein held the view that the world and, for that matter, the whole universe, is there independent of humanity. Tagore held the view that the world is a human world and hence without humanity, the world is irrelevant and non-existent. Einstein persisted and queried that aren’t beauty and truth absolute and independent of man? Tagore disagreed and said that truth is realised through man and without man it does not exist. The whole conversation between these two giants was absolutely fascinating – it brought out the mindset of a scientist seeking out nature as it exists and that of a poet observing nature through the eyes and minds of human beings.

Einstein’s commitment to the reality of nature was absolute, and that absolutism brought him into conflict with the quantum reality proposed by Niels Bohr, Werner Heisenberg and others. Einstein believed in the existence of causal, observer-independent reality; whereas quantum mechanics considers reality dependent on the act of observation. Bohr/Heisenberg proposed that an atomic particle like an electron is there only when it is observed. If it is not observed, it is not there; it could be anywhere only to be described by quantum functional description. But Einstein would not accept that. He retorted by saying that the moon is there in the sky whether you observe it or not. Quantum mechanics states that an entity having unobserved presence cannot be claimed to be present with absolute certainty (with the probability of 1). Quantum mechanics tell us that the observer and the observed are entwined. The reality is not pre-ordained; reality is what is observed.

In 1928, Tagore received Arnold Sommerfeld, professor of theoretical physics at the university of Munich and a pioneer of atomic spectra, at Shantiniketan, West Bengal. Sommerfeld stated, “Tagore is to India what Goethe (pronounced as Görta) is to Germany”. Sommerfeld’s student Werner Heisenberg visited India the following year.

Heisenberg was one of the principal architects of quantum mechanics and his ‘uncertainty principle’ is the cornerstone of quantum mechanics. During the 1920s, he, along with Niels Bohr and others, produced what is now known as the ‘Copenhagen Interpretation of quantum mechanics’, where multiple existence of an atomic particle at different locations with superposition of quantum states was considered to be the reality of nature.

Although quantum mechanics had enormous success and explained various physical phenomena, which classical physics was incapable of explaining, the conflict with Einstein on quantum mechanical fundamental assumptions of probabilistic description was deep rooted. Einstein considered quantum mechanics as an incomplete description of nature.

In 1929, when Heisenberg undertook a lecture tour around the world, he came to India. On 4 October 1929, he visited the University of Calcutta and in the afternoon, he visited Tagore. In fact, he was taken to Tagore’s house at Jorasanko by the scientist Debendra Mohan Bose, a nephew of Jagadish Chandra Bose, and they had a number of conversations over the next few days. Heisenberg was very much impressed by Tagore’s philosophical views. Fritjof Capra in his book Uncommon Wisdom wrote,:

“In 1929 Heisenberg spent some time in India as the guest of the celebrated Indian poet Rabindranath Tagore, with whom he had long conversations about science and Indian philosophy. The introduction to Indian thought brought Heisenberg great comfort. He began to see that the recognition of relativity, interconnectedness and impermanence as fundamental aspects of physical reality, which had been so difficult for himself and his fellow physicists, was the very basis of the Indian spiritual traditions.”

Heisenberg said, “After these conversations, some of the ideas that had seemed so crazy suddenly made much more sense. That was great help for me.”

Heisenberg’s comfort was to be seen in the context of a great intellectual battle that had been raging at that time between Einstein and Bohr/Heisenberg on the reality of nature. Indian mysticism or more accurately, Tagore’s interpretation of Oriental (Brahma) philosophy, giving a support to modern physics and quantum theory, was undoubtedly a great comfort to Heisenberg. No wonder, Heisenberg even said after their conversations that Tagore reminded him of a prophet of the old days!

Tagore’s philosophy of viewing the world with human eyes may seem to conflict with Einstein’s observer-independent reality, but these are two perspectives of the reality. Tagore’s view of reality resonates very well with the quantum philosophy of observer-dependent reality.

Dr A Rahman is an author and a columnist

Advanced science, Astrophysics, Bangladesh, Cultural, International, Life as it is, Literary, Religious, Travel

Einstein’s hand written letters are intensely sought after

Albert Einstein, the most famous scientist of the 20th century and the most iconic figure of a physicist, had lost not an iota of world’s admiration and fascination even after 65 years of his death. The world, it seems, is keen to grab whatever bits and pieces it can get bearing Einstein’s name or attachments at any price.

This was evident from the recent auction of a single-page hand written letter by Einstein in German to a Polish-American physicist Ludwik Silberstein by a Boston based RR Auction house. The interest in this hand written letter of Einstein was so intense that the auction started on the internet on 13th of May, 2021 with lots of internet bidders and concluded on 20th of May, 2021 when two anonymous final bidders slogged it out in a desperate bid to procure it and eventually it was sold for $1.2million (£850,000).

This Einstein’s letter written on 26th October 1946 on the Princeton University letterhead addressed to Ludwik Silberstein, who was a severe critic of Einstein, said cryptically, “Your question can be answered from the E=mc2 formula, without any erudition.” The letter was kept in Silberstein’s personal archives and nearly 70 years later his descendants retrieved it recently and sold it in the auction.

The letter in itself contained no new material of scientific or technical interest that may stir intense interest to anybody. The novelty was purely of Einstein’s hand-written element. In fact, it contained a somewhat incomplete mass-energy equivalence equation, which Einstein produced some 40 years earlier (before he wrote the letter) in 1905 and published in the Annalen der Physik, world’s leading physics journal at that time. The original equation that he produced was

                                    E = m c2 / √(1 – q2/c2

where E is the energy, m is the mass of a body when at rest,

            q is the speed of the body and c is the speed of light.

If the body is at rest, q is 0 and so the term within the square root is 1 and hence the equation becomes E = m c2. This is what Einstein communicated to Silberstein in his letter. If, on the other hand, the body happens to travel at the speed of light (most unlikely) meaning q = c, then the term within the bracket would become 0 and the energy becomes infinite. This indicates that nothing can travel at or above the speed of light.

A photo below where the full mass-energy equivalence equation that Einstein produced in 1905 is shown. This photo was taken by the author of this article when he visited Einstein’s apartment in Bern, Switzerland, which is now a museum, in 2017. At the top part of the photo, the Einsteinhaus (Einstein house, in Bern, Switzerland) is shown in which Einstein rented the second-floor apartment after he got married in 1903. His wife, Mileva Marić, is shown at the lower part of the photo. They lived there from 1903 to 1905. While living in that apartment, Einstein produced the special theory of relativity, the photoelectric effect for which he received the Nobel Prize as well as the above equation, all in 1905!

Einstein alongside his mass-energy equivalence

This was not the only letter that excited the collectors’ imagination of Einstein’s souvenirs world-wide. Eight years later in his life, in 1954 (just one year before his death), he wrote a letter to the German philosopher, Eric Gutkind, that drew even more interest. That letter, though, had material content of interest that expressed Einstein’s religious views. That letter had been sold in an auction at Christie’s in New York in 2018 for the staggering sum of $2.9 million (£2.3 million).

Religious people of all religious persuasions had been claiming that Einstein was a religious man, because of his quotation, “God does not play dice”. The interpretation from this quote, the religious people claimed, was that he believed in God’s absolutism and determinism in designing the universe. But the reality could not be furthest from this truth.

Albert Einstein made that remark as a riposte to the quantum physicists upholding the “Copenhagen Interpretation” that a fundamental particle’s existence is probabilistic in nature. Einstein held the view that a particle would exist or not-exist with absolute certainty, it cannot be probabilistic. His views were very well articulated in his one and half page letter written in German to the German philosopher, Eric Gutkind, “The word God is for me nothing more than the expression and product of human weaknesses, the Bible a collection of honourable but still primitive legends, which are nevertheless pretty childish”. He also said, “No interpretation, no matter how subtle, can change this”. Thus, his views on religion could not be more forthright than this and this letter had put an end to all those egregious interpretation of religious people.

Hounded by Hitler’s anti-Semitic ideology, Einstein had to leave Germany and eventually settle in America to work at the Institute of Advanced Studies, Princeton University in New Jersey. When he arrived at the Institute, he was asked, what equipment would he require to work properly. “A desk or table, a chair, paper and pencils”, he replied, “Oh, yes, and a large waste basket, so I can throw away all my mistakes”. He was working on the Grand Unified Theory (GUT) of physics, which would merge the four forces of nature into one unified force. He worked on this GUT for well over 25 years without being able to crack it and possibly made lots of “mistakes”. Those “mistakes” were not collected by the Institute, when it was under overwhelming pressure from the WWII events. But if it did, who knows those “mistakes” could give a technical direction to the problem he was tackling and bear handsome fortunes to the Institute in auction sales now.

The bits and pieces of great men (and women) of science and literature might be deemed “mistakes” and worthless now, but in the fullness of time those pieces might turn out to be invaluable gems. For example, when Einstein produced the general theory of relativity, he introduced a term called the “cosmological constant” in his equation to cater for the prevailing perception of static universe. Only a decade or so years later, when universe was found to be not static but expanding, Einstein admitted that the insertion of cosmological constant was the “biggest mistake” in his life. But now with the discovery of dark energy and dark matter, this cosmological constant is throwing a lifeline to the modern-day cosmologists. His admission of “biggest mistake” of cosmological constant itself seems to be a mistake.

Einstein’s contemporary man in the Eastern World, Rabindranath Tagore, the myriad-minded man and a Nobel Laureate in Literature in 1913, wrote a short but simple verse with a profound philosophical significance, which reads in Bengali:

Tagore’s verse:

যেখানে দেখিবে ছাই

উড়াইয়া দেখ ভাই

পাইলে পাইতে পার

অমূল্য রতন !

Translated into English, it could read like this:

                        Whenever you find ashes

                        Sift carefully my friend,

                        Might you even find

                        Gems invaluable.

Einstein was not only a man of great intellect, but also a great showman and a humorous individual. When he met Charlie Chaplin in January 1931, he said to Chaplin: “What I most admire about your art is your universality. You don’t say a word, yet the whole world understands you!”

“It’s true,” replied Chaplin. “But your fame is even greater; the whole world admires you, when nobody understands what you say.”

Dr A Rahman is an author and a columnist

Advanced science, Disasters - natural and man-made, Environmental, International, Life as it is, Technical

Amid global warming – why are we in a deep freeze?

Obverse effects of global warming

During winter, more often than not, a large part of northern United States is pummelled by an Arctic blast, sometimes severe, sometimes less so, that lasts for a week or two. But this winter’s blast plunged not only Midwest and Northeast into a deep freeze with bone-chilling temperatures as low as negative 45 degrees Celsius, but it also tested the mettle of millions of people living in the Deep South, particularly Texas, a state that seldom experience sub-zero temperature.

An onslaught of freak wintery weather—a cocktail of heavy snow, sleet and chilling ice storm—with sub-zero temperatures knocked millions of Texans off the power grid and plunged them into deep freeze, the lowest being negative 12 degrees in Houston. Frozen and burst water pipes in homes and businesses were widespread. Unlike northern states, Texas is not equipped to handle ice, sleet or snow. As a consequence, hundreds of vehicles, including dozens of 18-wheeler, were involved in horrific and sometimes fatal pileups on untreated icy roads.

The recent extreme weather is not limited to the United States. That is because when the winter is extreme in one part of the hemisphere, it is often extreme all across the hemisphere. Thus, the “beast” from the Arctic hit Europe too. In January, Spain experienced a deadly snow storm with dangerously low temperatures. Even a tropical country like Bangladesh, especially the northern region, could not escape the wrath of the cold wave.

Snow fell hard in Greece and Turkey, where it is far less normal. Snow also fell in Jerusalem and parts of Jordan and Syria, while snow-covered camels in Saudi Arabia made for a rare sight. We also had more than our fair share of snow. In the lower Hudson Valley of New York, where I live, Mother Nature already dumped around 36 inches of snow since the last week of January, with more in the forecast. Most of the snow—24 inches—fell in a single storm event from January 31 through February 2.

Climate change deniers have often used cold winter weather to advance their argument that global warming is a Chinese hoax. In one infamous example, when an Arctic freeze descended on the northeast, including New York City, in December 2017, former US President Donald Trump tweeted, “Perhaps we could use a little bit of that good old Global Warming to protect against” harsh winters. Only an ignoramus person like him could make such a stupid statement!

It may be counterintuitive, but paradoxically, among the many factors, anthropogenic climate change is mainly responsible for the short-lived bursts of extreme winter weather that we have been witnessing in recent years. Indeed, there is strong scientific evidence that rapid heating of the Arctic caused by global warming is pushing frigid air from the North Pole further down south due to distortion of the polar vortex.

Under normal conditions, cold air is concentrated in a huge low-pressure gyre around the North Pole in an area called the polar vortex—about 15 to 50 kilometres above the Earth’s surface in the layer of the atmosphere known as the stratosphere. When the vortex is strong, the jet stream—a narrow band of strong, fast-flowing wind in the upper atmosphere that generally blows from west to east all across the globe—acts as a barrier between the spinning cold air in the north and the warmer air to the south. As a result, cold air remains trapped in the Arctic, making winters in the northern mid-latitudes milder.

How does global warming distort the polar vortex? It is well-known that the rise in global temperature is not evenly spread around the world. Because of the loss of Arctic ice which otherwise would have reflected a substantial amount of solar radiation back into outer space, average temperature in and around the North Pole is increasing about twice as fast as in the mid-latitudes. This is known as Arctic Amplification. Several studies show that the amplification is particularly strong in winter. Consequently, a rapidly warming Arctic weakens the jet stream, which in turn weakens the polar vortex to the extent that it becomes distorted, thereby spilling its cold air southward.

According to meteorologists, in a span of two weeks from December to January, Arctic Amplification gave rise to a phenomenon called Sudden Stratospheric Warming, in which temperatures in the atmosphere 15 to 30 kilometres above the Arctic jumped by nearly 55 degrees, from negative 80 to negative 25 degrees. This accelerated warming weakened the jet stream considerably and subsequently distorted the vortex so severely that it got knocked off the pole, resulting in a sudden plunge in temperature south of the Arctic Circle all the way to the US-Mexico border. Hence, the once-in-a-lifetime cold winter in Texas and other southern states.

Continued rise in global temperature will not necessarily mean an end to bitter cold waves during winter any sooner. One group of researchers believe that Arctic blasts will still occur, but their intensity will depend on how much greenhouse gases we vent into the atmosphere. It is very probable that they will become rarer over time, but the ones we are experiencing now will more likely persist and last longer. Another group says that warming in the Arctic will increase the chances of frigid polar air spilling further south, leading to more periods of extreme cold days in the future, much colder than the ones we are experiencing now.

Nevertheless, the recent weather pattern clearly demonstrates that both extreme heat and extreme cold can happen side by side. Besides, two to four weeks of cold snaps do not make a winter. They are short-term weather events, while climate is about long-term trends. Arctic blasts are, therefore, not enough to compensate for the overall warming of the climate across the planet. In fact, last year was one of the hottest years on record, with the average temperature surpassing a number of all-time highs. And it occurred without the warming influence of El Niño.

Finally, we are in a deep freeze amid global warming because our “senseless and suicidal” romance with fossil fuels has fundamentally changed the global weather systems for worse.

Quamrul Haider is a Professor of Physics at Fordham University, New York.