Bangladesh, Environmental, International, Life as it is, Political, Technical

We are hurtling towards a disastrous climate change (Part I)

The human race is staring at the disastrous climate change of their own making. The climate change clock is ticking remorselessly; it has gone past the 11th hour and, although not exactly on the 59th minute, but not too far from it. We pride ourselves to be civilised human beings, we claim unprecedented scientific and technical achievements; but we have failed to realise the damage we have inflicted and still are inflicting on our planet and our actions are anything but civilised. A large section of the human population under the guidance and influence of ‘civilised political leaders’ in many Western and Eastern countries is in complete denial of the climatic damage!

In order to appreciate how close are we to the tipping point of the irreversible climate change, we need to look at the factors that initiate climate change. The term ‘climate change’ embodies the totality of processes like global warming, sea levels rise, loss of polar ice caps, floods, fires, droughts and so forth. These processes do not take place for no reasons; there are deep rooted reasons for these effects.

The causes for these effects are multifarious. Causes range from emission of greenhouse gases from uncontrolled industrial activities, excessive exploitation of Earth’s resources, deforestation, rise in human population, demands for improved standards of living, increased air travel etc. All these factors contribute to climate change due to enhanced greenhouse gas emission. And the quantity that is primarily used to characterise climate change is the increase in global temperature.

The root cause of the increase in temperature is the increase in greenhouse gas concentration in Earth’s atmosphere. A sort of runaway situation has developed here. Increase in greenhouse gas leads to higher global temperature and higher global temperature leads to higher greenhouse gas. Unless decisive action is taken by human beings to arrest this situation, the human race is at peril. 

The legitimate question that arises here is that how can one assert this rise in global temperature leading to climate change is mainly due to human activities, when both natural processes and human activities do contribute to global temperature? That is a genuine question.  

The planet Earth had undergone over the millennia large climate swings. Scientists had looked into these variations in Earth’s climate over the past 650,000 years and found that there had been as many as seven ice ages during this period and in between ice ages there had been some warmer periods with increase in global temperatures. Modern human beings (Homo sapiens) had not yet evolved 650,000 years ago and so global temperatures could all be assigned to natural causes. There was no trend of temperature variation over this period.

When nearly 250,000 years ago, modern human beings emerged from the savannas in Africa, man started interacting with nature. But those primitive men had no way of exploiting the Earth; they were passive, subservient onlookers of nature.

Climatologists looked at the inter-glacial periods i.e. between two cold glacial spells and established a baseline temperature. After the baseline temperature was established, then any excess global temperature found over a period when human activity was known to have taken place can be assigned to human activities. This is an established scientific technique and it is applied to many scientific disciplines to separate out human activities from natural activities.

The planet Earth is blanketed by a layer of gases in the outer atmosphere. This atmosphere containing a variety of gases lets in solar radiation to come through, but blocks out or shields harmful ionising radiation from the outer skies. A small fraction of solar energy is reflected back from Earth’s surface to outer skies. Normally if the atmosphere is unpolluted, this reflected energy in the form of infrared radiation will escape to outer space. On the other hand, if there are pollutants such as carbon dioxide, methane etc, this radiation is held back and reflected towards Earth again. Thus, gradually excess energy is accumulated in the planet and its temperature goes up.

The types of gases that refuses to let infrared escape from Earth had been found to be carbon dioxide (CO2), methane gas (CH4), nitrous oxide (N2O), chlorofluorocarbon (CFC) and a few more. Atmospheric concentrations of carbon dioxide in ppm (parts per million) and methane gas in ppm over the period 1500 to the present time had been estimated by scientists and presented in the graphs below. The period 1720 to 1800 is the industrial revolution period when human activities kicked in large scale. Before this industrialisation period, humans were living in harmony with nature. It can be seen from both of these graphs that the industrial revolution was the spurt in increase in concentration which continued in accelerated fashion right up to the present day.

Greenhouse gas concentration from 1500 to 2000 AD
(Courtesy: http://www.theconversation.com)

Along with these two graphs, one should consider the rise in global temperature which is shown below. The similarity in the overall shape and pattern of these graphs is striking and one can draw conclusion that are correlated. It shows beyond doubt that the rise in temperature above the 1850 to 1900 (industrialisation period) baseline is due to increased concentration of global warming pollutants – CO2 and CH4. There are other significant pollutants such as chlorofluorocarbon (CFC), but it is not shown here.

The CO2 concentration in pre-industrialised period was between 200 to 270 ppm and Earth had a thermally stable period. But now this concentration has risen to about 350 ppm leading to about 1ºC rise in temperature. But, if the present trend continues, by the end of the coming decade the temperature may well go up more than 1.5ºC and that would bring in very harsh conditions for all forms of life on Earth.

Global average temperature and industrial baseline.
(Courtesy: http://www.theconversation.com)

From 1970s the scientists had been saying that human beings are damaging Earth’s atmosphere and its natural conditions and care should be taken to limit it or even reverse it. But political leaders of various persuasions, particularly Americans and vested interests dealing with fossil fuels, kept denying any global warming or any climate change etc. When confronted with increased severity and more frequent incidences of droughts, bush fires, floods, storms, tropical cyclones, cold spells etc, these climate deniers started saying that these are natural phenomena; nothing to do with human activities. Their denial is either based on ignorance or moral depravity.

Few countries holding such views are destroying the good work of large number of countries. Donald Trump, president of America, is the most famous deniers of all, mainly because America is the second largest polluter of the world and to limit polluting activities would cost America a lot. And hence denying the whole thing is the easy option. Pursuing such damaging policy, America, under Donald Trump, had withdrawn from the Paris Agreement in 2017.

The Paris Agreement of 2015 aims to limit global warming to 1.5ºC relative to a pre-industrial baseline. Its precise commitment is:

Holding the increase in the global average temperature to well below 2℃ above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5℃ above pre-industrial levels, recognising that this would significantly reduce the risks and impacts of climate change.

We all live in the same planet. If one country i.e. America, the second largest polluter, keeps damaging the planet for its own benefit, that would wipe out the sacrifices of large number of countries. America is pushing the Earth to a precipice for their selfish interests.

(The next Part (Part II) will deal with the likely consequences of the present predicament and the most likely prediction of the future scenario.)

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  • Dr A Rahman is an author and a columnist
Bangladesh, Economic, Environmental, International, Life as it is, Technical

Our oceans: The ultimate sump

Plastic pollution

Today is “World Oceans Day,” a day observed worldwide to raise awareness about the crucial role the oceans play in sustaining life on Earth. It is also a day to appreciate the beauty of the oceans that “brings eternal joy to the soul.”

The oceans are among our biggest resources and also our biggest dumping grounds. Because they are so vast and deep, many of us believe that no matter how much garbage we dump into them, the effects would be negligible. Proponents of dumping even have a mantra: “The solution to pollution is dilution.” Really! In case they don’t know, garbage dumped into the oceans is continuously mixed by wind and waves and widely dispersed over huge surface areas.

There is a zone in the Pacific Ocean, called The Great Pacific Garbage Patch, which is a gyre of marine garbage twice the size of Texas. The garbage, mainly microplastics, were carried there by strong currents from other parts of the ocean. This is not the only floating garbage in our oceans. The Atlantic and Indian Oceans have their own garbage patches. Worse yet, the sheer size of the patches is making clean-up efforts an extremely difficult task.

Surely, human activities are impacting the oceans in drastic ways. Some of the anthropogenic environmental issues that are affecting the oceans are plastic pollution, oil spills, climate change and noise. One of the most dangerous threats the oceans may face in this century is radioactive pollution.

Each year, we dump nearly eight million tonnes of plastic—mostly grocery bags, water bottles, yogurt cups, drinking straws and plastic utensils—into the oceans. Recently, plastic has been discovered in the deepest part (11 kilometres) of the world’s oceans, Mariana Trench in the Pacific Ocean. Extremely elevated concentration of PCBs, an environment-damaging chemical banned in the 1970s, have also been found within the sediment of the trench.

While it takes hundreds of years for plastics to decompose fully, some of them break down much quicker into tiny, easy-to-swallow particles that can easily be ingested by marine species causing choking, starvation and other impairments.

Pollution of the oceans by oil spills has been one of the major concerns for a long time. The primary source of spill is offshore drilling. The process is inherently dangerous and thus, is prone to accidents. When accidents happen, and they do happen without warning, they cause massive damage to the environment—aquatic and shore—that persists for decades to come. Some oil spills happen when tankers transporting petroleum products have accidents.

If the layer of the oil is thick enough, it smothers creatures unable to move out from under it. Besides, swimming and diving birds become covered with oil, which mats their feathers, reducing their buoyancy and preventing flight. The insulative value of feathers is also lost and the birds quickly die of exposure in cold water.

The world’s largest oil spill was not an accident; it was the result of the Persian Gulf War in 1991. The second worst disaster was the spill by BP’s Deepwater Horizon offshore rig in the Gulf of Mexico in April 2010. Both incidents killed tens of thousands of birds, marine mammals, sea turtles and fish, among others.

Land and oceans together absorb slightly more than half of all the carbon dioxide emissions, with the oceans taking a greater share. When carbon dioxide dissolves in water, it forms carbonic acid. Various studies estimate that if we keep on pumping carbon dioxide into the atmosphere at the current rate, then by the year 2100, the water of the oceans could be nearly 150 percent more acidic than they are now. Such a large increase in acidity would upset the productivity and composition of many coastal ecosystems by affecting the key species at the base of the oceanic food webs. It would also reduce calcium carbonate, which is essential for building the shells and skeletons of creatures like mussels, clams, corals and oysters.

Because oceans absorb more than 90 percent of the heat that is added to the climate system, sea level is changing, albeit unevenly. It is changing unevenly as oceans do not warm uniformly across the planet, with the southern oceans warming at a faster rate. In addition, global reef systems are slowly migrating poleward as oceans around the world continue to warm.

The single most significant contribution to rising sea level is from the thermal expansion of water. Melting ice makes the second most important contribution, but only melting of land-based ice—glaciers, ice caps and ice sheets—is significant. Ice that is already floating in the water—iceberg—makes essentially no change in sea level when it melts, because the greater density of water offsets the volume of ice that is not submerged. Other factors that contribute to the rise in sea level include wind and ocean circulations, depth of the oceans, deposition of sediments by river flows and alteration of the hydrologic cycle by humans.

According to some studies, global sea level rose by about 18 cms during the last century. In the worst-case scenario, sea level could rise by two metres by the end of the year 2100. Arguably, rising sea level is among the potentially most catastrophic effects of human-caused climate change.

The oceans are no longer “The Silent World” of the famous oceanic explorer Jacques Cousteau. Today, they are being acoustically bleached by noise from seismic blasts used for offshore oil and gas exploration, marine traffic and military sonar.

Unlike plastic pollution, noise pollution does not have the visual impact that is needed to spark an outcry and force action. It is an invisible menace that is drowning out the sounds of many marine animals, including fish, use for navigation, communicating with each other, finding food, choosing mates and warning others of potential dangers.

Whales and dolphins are particularly vulnerable to noise pollution. The deafening seismic blasts and the ping of sonar are responsible for the loss of their hearing and habitat, and disruption in their mating and other vital behaviours. The disappearance of beaked whales in the Bahamas in recent years have been attributed to testing of US Navy sonar systems in the region.

From 1946 through 1993, nuclear countries used the oceans to dispose of radioactive wastes. The United States alone dumped more than 110,000 containers of nuclear material off its coasts. Russia dumped some 17,000 containers of radioactive wastes and several nuclear reactors, including some containing spent nuclear fuel.

It is highly likely that radioactive wastes would eventually leak out of the containers because of poor insulation, volcanic activity, tectonic plate movement and several other geological factors. Indeed, last month, UN Secretary General Antonio Guterres confirmed that a Cold War era concrete “coffin” filled with nuclear waste is leaking radioactive material into the Pacific Ocean. Since radiation from nuclear wastes remains active for hundreds of thousands of years, their dangerous effects will linger for a long time and will have lethal impact on marine life.

Furthermore, six nuclear submarines — 4 Russian and 2 American — lost as a result of accidents are lying at the bottom of the oceans. They represent serious threat of radioactive contamination of the oceans, too.

One of the biggest contaminations due to radiation was caused by a series of nuclear tests conducted by the USA on the sea, in the air and underwater at Bikini Atoll in the North Pacific between 1946 and 1958. The French nuclear tests carried out during 1966-1996 in French Polynesia are responsible for other cases of intense radioactive pollution of marine ecosystems.

Clearly, we are using the oceans as the ultimate sump, partly because their very immensity seems to preclude any long-term effect, and partly because they belong to no one. This cannot continue indefinitely because in order for us to survive, we have to protect the oceans. Lest we forget, life emerged from the oceans and the source of most of the oxygen we breathe are the oceans. They have been an endless source of inspiration to humankind.

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

Advanced science, Bangladesh, Environmental, International, Life as it is, Technical

Cyclone Fani and global climate change

The temperature of the Earth changes over geologic time. During periods of glaciation, it was about five degrees Celsius cooler and in the interglacial period about five degrees warmer. The last glaciation period was 100,000 years ago. Since then, there have been fluctuations of a few degrees, the period of 1430 to 1850 being one of particularly low temperatures in Europe. Although there were fluctuations from year to year, it seems evident that there has been a steady increase in average global temperature since the Industrial Revolution. According to the World Meteorological Organization, average global temperatures will reach a new milestone this year—one whole degree higher than temperatures before industrialisation.

In the early 1990s, when concern about climate change caused by the rise in temperature became widespread, the “signal” of anthropogenic effects hadn’t unambiguously emerged from the “noise” of natural climate variability. However, we now know that most of the climate-related changes observed over the past 50 years is attributable to human activities. In fact, by burning prodigious amounts of fossil fuels that emit carbon dioxide, which is the principal greenhouse gas, we humans have taken Earth’s atmosphere in general and global temperature in particular into a regime that our planet hasn’t seen for millions of years.

Although the interplay between carbon dioxide and temperatures is complex and not necessarily 100 percent predictive, nevertheless, the obvious correlation between the two variables suggests that we might expect a significant adverse climatic response to the industrial-era surge in fossil fuel derived atmospheric carbon dioxide. Undeniably, the effects of this interplay are manifested in the increase in the ferocity of storms, floods of biblical proportions, spike in the number of unusually hot days, melting of the glaciers, drought, desertification and deforestation, polar vortex, uncontrollable forest fires, degradation of the coral reefs, habitat loss and rise in the sea level, to mention a few.

Today, because of global warming, intense storms are occurring in many parts of the world. If they form in the Atlantic or Caribbean, they are known as hurricanes, and in the Pacific or China Sea as typhoons. If they develop off the coast of Indian Ocean or the Bay of Bengal, we call them cyclones. These storms are one of the most awe-inspiring displays of the raw power of nature. They are also among the deadliest and costliest natural disasters we have to contend with routinely.

After churning through the Bay of Bengal for several days, gathering immense amount of energy along the way, cyclone Fani roared through Bangladesh on May 4, 2019, leaving behind a massive trail of destruction—killing more than a dozen people, knocking out power, shredding roofs and leaving hundreds of thousands homeless. Classified by meteorologists as the equivalent of a Category 4 hurricane, it was one of the most intense cyclones in 20 years in the region.

Cyclones batter Bangladesh at regular intervals, mainly in April/May or October/November, when weather conditions align in a manner most favourable for storm origination and sustenance. As examples, cyclones Aila struck southern Bangladesh on May 27, 2009 and Sidr made landfall on November 14, 2007. The occurrence of these and other cyclones in close succession is a reminder of the country’s extreme vulnerability to the devastating effects of human-induced climate change.

The 1970 cyclone that hit Bangladesh on November 12 and raged the strongest on November 13 was the worst natural disaster we have witnessed so far. The resulting storm surge, more than 20 feet high and topped by huge tidal waves, washed over offshore islands and carried water from the sea many miles inland. The cyclone and flood destroyed the entire infrastructure of the country’s southern coast and killed an estimated half a million people, though some researchers estimate that the death count was close to a million. The failure of the Pakistani government to respond quickly to the crisis, among other things, contributed to the political turmoil that led to an independent Bangladesh in 1971.

Tropical cyclones are influenced by many factors, but the role of warm sea-surface temperatures is the primary source of energy for cyclones. In particular, a cyclone gets most of its energy from the latent heat of condensation and the moisture generated from the sea. Thus, for the genesis of cyclones, temperature of water near the surface of the sea must be higher than 27 degrees to a depth of at least 150 feet. Additionally, heat from the sea and Earth’s counter-clockwise rotation conspire to create the cyclone’s spin and propulsion. Furthermore, rising sea levels mean that surges produced by cyclones are much more powerful, thereby increasing the risk of inland flooding.

Moreover, cyclones need to be at least 300 miles from the equator, where a deflective force known as Coriolis force resulting from Earth’s rotation begins to take effect. When cyclones reach land, or cooler water, they lose energy as the conditions necessary to reinforce them are no longer present.

As a result of global warming, temperature near the surface of the Bay of Bengal varies from 27 degrees in January to more than 31 degrees in May. The unusually warm water, together with geographical and environmental factors, make the Bay of Bengal a hot spot for cyclonic activity.

Can changes in frequency and intensity of cyclones observed so far be attributed solely to anthropogenic global warming as against long-term periodic natural variations? Cyclones are affected by natural fluctuations too, driven by external factors, such as solar variability and volcanic eruptions, natural internal variations of the complex physical, chemical, and biological systems of Earth.

Additionally, research has shown that urbanisation significantly contributes to the amount of rainfall dumped, as evidenced by over 130 centimetres of rain that fell on the Houston region during hurricane Harvey in 2017. This is because the “roughness” of the city—as in the buildings and infrastructure—creates a drag on the storm system, causing it to slow down, resulting in more rain over the city area.

Climate models predict that global warming could spawn more bizarre and violent weather, notably cyclones and severe floods in the future. Indeed, while people are trying to come to grips with the effects of Fani, meteorologists have warned that Bangladesh is likely going to experience another cyclonic storm called Vayu some time later this month.

The models also predict that by the end of this century, global warming effects could increase a cyclone’s intensity by about 20 percent, making them more destructive than ever. The amount of rainfall would also increase substantially. Other estimates predict that a doubling of carbon dioxide concentration would result in a 40-50 percent increase in destructive cyclones.

So, what should we do to keep our planet in the so-called Goldilocks zone of the solar system? We have to make a concerted effort to end our dependence on fossil fuels. We have to replace them with non-polluting, renewable sources of energy. We have to develop more carbon-free energy technologies. We have to sequester carbon dioxide emissions using the available technology. More importantly, we have to shun the “business as usual” attitude. In short, we will have to build a sustainable future. Otherwise, climate change will cause our civilisation to collapse.

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

Advanced science, Astrophysics, Cultural, International, Technical

Mysterious dark matter and dark energy

Physics is traditionally viewed as a hard subject requiring a great deal of mathematical prowess, devotion and perseverance to muster the subject matter. To a large extent, it is definitely true. But it does also offer, in its turn, a great deal of satisfaction, excitement and sense of achievement.

The 21st century physics, spanning from quantum computing to super-thin layer material called graphene to ultra-efficient LED bulbs to efficient harnessing of renewable energies to black holes to dark matter and dark energy, the range of topics is endless and it will disappoint no one with its vast challenges and ensuing excitement.

In our day-to-day lives, we encounter matter comprising protons and neutrons bundled together at the centre, called nucleus, of an atom and electrons whizzing around the nucleus. Some decades ago, these protons, neutrons and electrons were thought to be the fundamental particles of all matter; but not anymore. Now, quarks (six types) are thought to be the fundamental matter particles, which are glued together by force particles to form protons and neutrons.

These atoms and molecules making up matter here on earth are what we are accustomed to. The laws of physics, or for that matter of natural sciences, were developed to explain the natural processes as we encounter in our lives.

The basic physical principles are like these: a body has a definite size comprising length, breadth and height; it has a mass and weight; it is visible when there is sufficient light. If we push a body, we impart momentum, which is the product of mass and velocity. As it has the mass, it has gravity, meaning it attracts every other body and every other body attracts this body. These are the basic properties of a body as described in classical physics.

But there is no reason to be dogmatic about these basic principles. These principles can change here on earth or in our galaxy or somewhere outside our galaxy. When they do change, we would feel that things have gone topsy-turvy.

We live on a very tiny planet, called Earth, which revolves round the star, called Sun. There are eight other planets, thousands of satellites, comets and asteroids, all held together by the gravity of the Sun. The Sun, though extremely bright and overwhelmingly powerful to us, is a small star in our galaxy, called the Milky Way. It is estimated that there are over a billion, yes, 1,000,000,000 stars, many of them are much bigger than the Sun, in our galaxy. Now our galaxy is by no means the biggest or dominant galaxy in the universe. Cosmologists estimate that there are around one billion galaxies in our universe! Some of these galaxies are hundreds or even thousands of times bigger or massive than our galaxy. There are massive black holes at the centres of most of the galaxies, exerting gravitational pull to keep the galaxy together. Some of these black holes are millions of times bigger than the Sun. Now we can have a feel of how big our universe is!

Physics, or more appropriately astrophysics, studies the processes of these vast expanse of celestial bodies. The Sun as well as our galaxy, the Milky Way having over a billion stars are not static. The stars are spinning, the galaxy is spiralling, and everything is in motion.

Strange glow from the centre of the Milky Way

It was estimated, purely on physical principles, that the stars at the edges of a galaxy should move slower than the central ones, as the force of gravity of the galaxy is weaker away from the centre. But astronomical observations show that stars orbit at more or less at the same speed regardless of their distance from the centre. That was a great surprise, indeed shock, to the astrophysicists. The way this puzzle was eventually tackled was by assuming that there are massive unseen matters that exert tremendous amount of gravitational pull to keep the outlying stars moving at nearly the same speed and that mysterious matter is called the dark matter.

There are other tell-tale signs that there is something amiss in the material accounting of the universe. A strange bright glow spread over the length of the Milky Way was thought to be due to ordinary pulsars (pulsating stars) along the length. But now it is thought that dark matter may be responsible for this glow! But how does it do that, physics does not know yet.

But is this dark matter a fudge to solve the apparent conflict of physical behaviour with observations? Not really, this is how science progresses. Well thought out ideas are advanced and those ideas are tested and cross-examined against observations and the idea or concept that passes the tests is taken as the valid scientific concept.

But how do we know dark matter is there, if we cannot see them. We cannot see them because dark matter does not interact with light or electromagnetic radiation such as visible light, infra-red, ultra violet, radio waves, gamma rays and so on. Light goes straight through the dark matter, as if it is not there.

It should, however, be pointed out that dark matter is not the same thing as black hole. A black hole is made up of everyday particles (matter particles and force particles) – electrons, protons, neutrons, atoms, molecules, photons etc. Its gravity has just become so strong (because of its mass and super-compacted size) that it pulls and crushes everything to its core and nothing can escape from its clutches, not even light! A beam of light coming close to a black hole is pulled right insight and that is the end of that light beam never to be seen again!

Dark energy expansion

Dark matter, although invisible, does exert gravitation pull and this gravitational pull that makes dark matter attractive to scientists. The Universe, although expanding, is not in danger of runaway expansion. There is something that is holding the whole thing together and that something may be the dark matter.

Immediately following the Big Bang, the then Universe expanded very rapidly, known as inflationary phase, for tens of millions of years followed by expansion for some billion years and then it stabilised for a few billion years and now it is again in the expansion phase. The present expansion is that the space itself is expanding and so every star and every galaxy is moving away from every other star or galaxy. What is giving these celestial bodies energy (repulsive in this case) to move away from each other? Scientists came up with the proposition that there must be some unknown, unseen energy, which is now called the dark energy.

On purely material and energy balance of the Universe, it is thought that our visible (and known) Universe accounts for only 4.9 percent of the total Universe, dark matter accounts for 26.8 percent and dark energy for 68.3 percent. So, we only know in the vast mind-boggling universe extending over 13.8 billion light years a meagre 5 percent and the remaining 95 percent is hidden or unknown to us!

Scientists all over the world are trying hard to find evidence of dark matter and dark energy. CERN’s Large Hadron Collider (LHC) is trying to find any remotest evidence of dark matter and energy. On theoretical basis, some scientists are proposing that dark energy may emanate from a fifth form of force, which is yet unknown. The four forces that we know are electromagnetic, weak nuclear, strong nuclear and gravitational forces. The fifth force may be a variant of gravitational force – a repulsive gravitational force – that comes into play in the vast intergalactic space.

When Einstein produced the general theory of relativity in 1915, he introduced, almost arbitrarily, a parameter, called the cosmological constant, into the theory to counter the effects of gravitational pull and make the Universe a static one. That cosmological constant effectively introduced the repulsive effects. It may be pointed out that the Universe was thought to be static at that time. But only a few years later when it was incontrovertibly shown that the Universe was, in fact, expanding, Einstein humbly admitted that it was his “biggest mistake”. Now, more than hundred years later, it is assumed that the cosmological constant may be considered to be the quantity to cater for the dark energy! Could Einstein’s “biggest mistake” be a blessing in disguise, it offers not only a correct presumption but also a saviour of modern cosmology?

  • Dr A Rahman is an author and a columnist

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

Isn’t black hole a black mystery?

A black hole – hitherto an invisible celestial body – was in cosmological vocabulary even before Einstein’s theory of relativity in 1915. But when the relativity theory predicted with full scientific rigour that a massive stellar body can have such a strong gravitational pull that nothing, no object, not even electromagnetic radiation such as light, can escape from it, the concept of a black hole became firmly established in scientific parlance. But it remained at that time only a mathematical curiosity, as no scientific evidence or mechanism of formation of a black hole was put forward. However, it became a realistic possibility after the detection of pulsars some decades later.   

The detection of pulsars (rotating neutron stars) by Jocelyn Bell Burnell, a research student at the University of Cambridge in 1967, gave renewed spurt to the concept of gravitational collapse and the formation of black holes. A normal star, when it comes to the end of its life due to lack of fusion fuel, collapses under its own gravity and becomes a neutron star. It may be mentioned that an atom consists of neutrons (neutral in charge) and positively charged protons and negatively charged electrons. If gravity becomes too strong, protons and electrons are pulled together to merge with each other, neutralise their charges and become neutrons and the whole star becomes a neutron star. (For the detection of neutron star, which was considered as “one of the most significant scientific achievements of the 20th century” by the Nobel Committee, her supervisor and another astronomer were awarded Nobel prize in Physics in 1974, but Jocelyn Bell was not even mentioned in the citation. However, years later, in 2018, she was awarded the Special Breakthrough Prize in Fundamental Physics. She donated the whole of the £2.3 million prize money to the Institute of Physics in the UK to help female, minority, and refugee students become physics researchers.

Not all stars eventually become neutron stars. If the mass of a star is less than 2.6 times the mass of the Sun, the gravity would not be strong enough to turn it into a neutron star. The gravitational pull in a neutron star ultimately becomes so strong that all its mass and its nearby matters are pulled to a small volume and the star becomes a black hole. A black hole can merge with another black hole to become a bigger and stronger black hole.

It is speculated that there are black holes of various sizes in most of the galaxies and in some galaxies, there are supermassive black holes at their centres. The nearest black hole from Earth is quite a few thousand light-years away; but they exert no influence on this planet. The supermassive black hole in our galaxy (the Milky Way) is about 26,000 light-years away.

Despite the name, a black hole is not all black. The gas and dust trapped around the edges of the black hole are compacted so densely and heated up so enormously that there are literally gigantic cauldrons of fire around the periphery of a black hole. The temperatures can be around billions of degrees!

The first direct visual evidence of a black hole had been produced on 10 April 2019 by a team of over 200 international experts working in a number of countries. The Event Horizon Telescope (EHT) was used to detect the existence of a colossal black hole in M87 galaxy, in the Virgo galaxy cluster. The computer simulation from data collected in the EHT is shown below. This black hole is located some 55 million light-years from the Earth and its estimated mass is 6.5 billion times that of the Sun! So, this black hole is truly a monster of a black hole.

Computer simulation of black hole from real data

Although it is a monstrous black hole, its size is quite small and it is enormously far away (520 million million million kilometres away) from Earth. To observe directly that elusive black body that far away, astronomers require a telescope with an angular resolution so sharp that it would be like spotting an apple on the surface of Moon from Earth and the aerial dish that would be required for such a detection would be around the size of Earth! Obviously, that is not possible.

Instead, the international team of experts devised a Very Long Baseline Interferometry (VLBI) technique, which involves picking up radio signals (wavelength 1.3 mm) by a network of radio telescopes scattered around the globe. The locations of these eight radio-telescopes are shown below. When radio signals from these radio-telescopes are joined up, taking into account their geographical locations, lapsed times for signal detection etc, and processed in a supercomputer, an image can gradually be built up of the bright part of the periphery of the black hole.

Locations of Event Horizon Telescopes (EHT)

The key feature of a black hole is its event horizon – the boundary at which even light cannot escape its gravitational pull. The size of the event horizon depends on the mass of the black hole. Once an object crosses the boundary of the event horizon, there is absolutely no chance of coming back. A lead astronomer from MIT working on this EHT team said, “Black hole is a one-way door out of this universe.”

The general theory of relativity also predicted that a black hole will have a “shadow” around it, which may be around three times larger than the event horizon size. This shadow is caused by gravitational bending of light by the black hole. If something gets nearer the shadow, it can possibly escape the gravitational pull of the black hole, if its speed is sufficiently high (comparable to the speed of light).

It is postulated that the “shadow” comprises a number of rings around the event horizon. The nearer a ring is to the event horizon, the more rigorous and compact it is with extreme pressure-temperature conditions. 

If, hypothetically, an unfortunate human being falls even into the outer ring of a “shadow”, he will be pulled towards the black hole initially slowly and then progressively strongly – his leg will be pulled more vigorously than his upper part and consequently, his body will be deformed into a long thin strip like a spaghetti. And when that spaghetti shape crosses the event horizon, it will be stretched so much that it will become a very thin and very long string of atoms!

Is wormhole the link between a black hole and a white hole?

The general perception of a black hole is that it is a monster vacuum cleaner where everything, even light, is sucked into it through a funnel and nothing, absolutely nothing, can come out. It absorbs enormous amount of matter and squashes them into tiny volumes. What happens to this gigantic amount of matter is a mystery, a black mystery.

There are two parallel streams of pure speculative thoughts. One is that when a black hole becomes too big – either by incessantly swallowing up matters from its surroundings or by merger with other black holes – a super-giant explosion, more like a big bang, may take place. So, a black hole may be the mother of a new big bang, a new generation of universe.

The other thought is that the funnel of a black hole is connected through a neck, called the wormhole, to a different spacetime and hence a different universe at the other end. All the materials that a black hole sucks up at the front end in this universe go through the wormhole to another reverse funnel where all the materials are spewed out into a different spacetime. That funnel is called the white hole. Thus, a black hole and a white hole is a conjugate pair – a connection between two universes!  But the question is, since there are billions of black holes in our universe, then there could be billions of corresponding wormholes and white holes and universes.

One universe is big enough or bad enough for human minds to contemplate, billions of universes will make humans go crazy.

Dr A Rahman is an author and a columnist