The constituents of the universe: space, time, matter and energyAuthor: Subir Kumar Bhattacharyya
While I am defining that space, time, matter and energy are the ultimate and basic ingredients of the universe, scientists will not stop at that and add another element, that is, the laws of physics, elegantly explained and formulated in mathematics. The entire domain of science that encompasses the whole gamut of our life- where we live, that is, the entire universe, why we live and what is life all emerges from the four basic constituents as theorized above like hundreds or thousands or more of descendants emerge from a single parent. The scientists have gone further to theorize that everything was created and evolved and is still evolving from a single element, that is, energy. Laypersons are sure to scoff at this proposal, because of age-old belief based on our senses, particularly from the influences of religions, lack of scientific education and usual aversion to new ideas. Even poets, litterateurs and eminent artists practising fine art and performing arts may question how these crude elements could bequeath nature so many colours, varieties, so much charm, grandeur and captivating beauties and humans such divine virtues and sublime traits and such bonds of love, parental affection, adoration and loyalty as make this planet earth an enchanting abode that none is willing to part with. The scope of any essay for publication in a newspaper is limited, but the expanse, depth and dimension of the subject is so colossal and all encompassing that the entire scientific knowledge comes under its purview. I shall attempt at explaining why my suggestion makes sense, but at the same time confess that I may not be able to do justice fully to the article in this format. In future, I shall revert to this subject from time to time to satisfy curious readers.
The laws of physics are expressed in terms of mathematics because the latter is the lingua franca of the universe. Most of the mathematical formulae are inaccessible to laypersons and as such it is always challenging to explain all these phenomena in simple language. The concept of space, time and spacetime combined is still evolving as there are three/ four competing concepts. I shall dwell on these later and begin with matter and energy, the concepts of which are resolved and discernible, but theories are still evolving in search of unification and elegance. Everything we see in nature however pretty, majestic and tender is divisible and can be separated into molecules and further split into atoms of any or more in combination of 92 elements occurring in nature. There are some man-made elements. The difference between living beings, both floral and faunal species including humans (Homo sapiens) and non-living objects is that the former is made of organic molecules while the latter made of inorganic molecules. Organic molecules are basically carbon compounds. Colours are properties of substances to absorb and emit one or more colours of light-spectra. The light-spectrum, which consists of seven visible light colours (acronym VIBGYOR) and invisible light waves such as ultra-violet, x-ray and gamma-ray on the left side of the spectrum (more energetic light waves) in that order and infrared, microwave and radiowave on the right (much less energetic), is in fact various frequencies of light waves perceived by our brain through inputs from eyes as different colours to differentiate among various frequencies. Colour perception varies from species to species. As such they are not fundamental property or reality of nature, but its perception is the creation of our brain to optimize the chances of our survival. The diversity that we see in nature is the variation in molecular structure formed by the atoms of ninety-two elements in different combinations. Most of the atom is just empty space. The rest of the atom consists of a positively charged nucleus of protons and neutrons (neutral or no charge) that are surrounded by a cloud (existing like waves) of negatively charged electrons. Protons and neutrons are not fundamental constituents of matter/ atom, they are made of quarks. The nucleus is the center of the atom. An atom is an extremely small particle of matter that retains its identity during chemical reactions.
Avogadro's number and the mole are very important concept for the understanding of atomic structure. Avogadro's number is 6.02 x 1023, and the atomic mass number (no of protons and neutrons) in grams is the mass/ weight of 1 mole of that element. One mole of an element or a compound contains 6.02 x 1023 atoms or molecules. For example, one mole of magnesium atoms or 6.02 x 1023 magnesium atoms weigh (12 protons plus a little heavier 12 neutrons in the nucleus of one atom) 24.3 grams. A mole of carbon or 6.02 x 1023 carbon atoms weigh a total of 12.0 (6 protons plus 6 neutrons) grams. An example may be given to show how small an atom is. If an apple were magnified to the size of the earth, the atoms in the apple would be approximately the size of the original apple. Atoms can only be observed individually using special instruments such as the scanning tunneling microscope. Over 99.94% of an atom's mass is concentrated in the nucleus with protons and neutrons having roughly the equal mass, neutron being slightly heavier. A molecule of any matter is much heavier than individual atom constituting the molecule. As for example, a mole of sand, spread over the United States, would produce a layer 3 inches deep while one mole of oxygen weighs 16 grams and that of silicon weighs 28 grams.
The size of the nucleus is much smaller than that of the whole atom. The radius of a nucleus is approximately equal to (1.07)3√A fm, where A is the total number of nucleons or the total number of protons and neutrons. The radius of an atom is in the range of 105 fm. 1 fm or femtometer is equal to 10 to the power minus 15 (10-15) meters. In comparison, the ratio of the radius of helium atom vis-à-vis that of its nucleus is 40,000:1. If we consider the shape of both the atom and its nucleus to be spherical, the volume of the atom (volume= 4/3pi times r3) is 64x1012 times that of the nucleus. This explains how infinitesimal the volume of the mass (ignoring the mass of electrons) is compared to the volume of the empty space inside the atom. Then how is it that we feel solidity of matter? It is because of interplay of various forces inside atoms, between atoms, inside molecules and between molecules constituting matter. Many mechanical, electrical, magnetic, optical and chemical properties of solids are the direct consequence of Pauli's exclusion principle, meaning that no two fermions (an electron is a fermion) can occupy the same quantum state. Energy can be defined as the ability of a system/ body/ force to exert pulls or pushes against the basic forces of nature, along a path of a certain length. The total energy contained in an object is identified with its mass, and energy like mass cannot be created from nothing or destroyed. According to Einstein's famous equation E = MC2 (it is considered the most famous equation in science), mass can be converted to energy and energy to mass, provided there is enough energy. 1 kg of mass has the energy equivalent of 9 x 1016 Joules and as such 1 gram has the energy equivalent of 9 x 1013 Joules. However, only a fraction of mass can be converted to energy. Nuclear reactors employ fission process to generate energy (electricity is a form of energy). Fusion process that keeps stellar including solar energy output alive converts hydrogen (hydrogen used as fuel) into helium, and a fraction of mass is converted to energy. Fusion process releases much more energy than fission process does. However, controlled fusion so far remains beyond the reach of human ingenuity.
Human qualities and virtues did not become the standard traits of human character at once, they evolve over time. We must remember only such qualities became our defining characteristics as enhanced the chances of our survival. All human qualities including defining characteristics of emotion like love, compassion, filial affection, loyalty, adoration and negative attributes like hate, revenge and cruelty and so on are encoded in our genes contained in the DNA inside our cell nucleus and passed down to succeeding generations. These emotion and traits are the result of interactions and sharing of neurons in the brain. In fact, all traits that we possess individually are the result of interplay among genes, environment at home and outside, upbringing and some luck, meaning that some favourable factors what we call luck. Human behaviour, propensity and the like are now greatly understood because of advancement in neuroscience. Further elaboration is beyond the scope of this article and I wish to stop here.
While explaining how human characteristics have evolved over time, I wish to put down a few lines on consciousness, the perception or impression of being before I dwell on matter and energy. Although neuroscience is developing, neuroscientists have discerned how brain creates emotions and are unanimous presently in their opinion that we, the humans, have no free will, validating the long-held belief among the scientific community that the free will or the strong feeling that we are in charge is in fact an illusion. Elaborating further, our brain always maintains a 3-dimensional picture of our surroundings; constantly updating the mental picture drawn from inputs received from sensory organs and makes us act in consonance with that picture. The brain takes inputs from senses by electrical impulses and processes them in various constituent parts of the brain and transmits decisions (outputs) or reactions that various organs of our body need to act on in response to the environmental stimuli. The time lag between reception of inputs to and transmission of outputs or instructions from the brain to executing organs ranges from 3/4th of a second (opinions about lower range vary from half a second to as long as 1 second) to several seconds. But the brain has to take instantaneous decisions in response to stimuli. Because of the compulsions under which the brain functions, it is only logical that it reacts according to mental picture, not in direct response to environmental stimuli. At the conscious level, the brain occasionally takes corrective measures (they could be hazardous occasionally) deviating from mental pictures in case it finds that the pre-conceived response is not adequate for survival.
Now reverting to matter and energy, I explain some fundamental laws of physics and draw the subject to a wholesome conclusion. According to the ‘Standard Model' of particle physics, there are four fundamental forces of nature- electromagnetic force (light, electricity and magnetism combined), weak nuclear interactions or force, strong nuclear force and gravitational force and several dozens matter particles and number of assumptions. They interact with one another according to the laws of physics and produce everything what we see in nature. An example will explain how the number of fundamental particles has grown over time. In an atomic structure, electrons revolve round a nucleus consisting of protons and neutrons, protons being positively charged and neutrons neutral. All protons should have been scattered and not confined within the nucleus because like charges repel each other. Scientists first theoretically deduced and then experimentally verified that masons hold them together. It was further discovered that protons and neutrons are made of quarks, and these fundamental particles cannot exist in isolation, they must combine to form proton and neutron and their electric charge is a fraction and not an integer. Scientists then found out why quarks always paired up because strong nuclear force holds them together (the force particle is gluon). In this way, scientists proceeded to discover new fundamental particle to account for specific behaviours. The existence of all these fundamental particles was verified experimentally in laboratories. Quantum mechanics explains the behaviours of particles and cosmic phenomena at the micro level and theory of relativity explains at the macro level, that is, behaviours of large-scale structures like stars and galaxies. Both these theories hold good in their respective fields but they are not compatible meaning that when they are combined to account for black holes and so on, absurd results come out. Grand Unification Theory (GUT) was postulated to unify three forces in nature except gravity. As the models described above are inelegant, scientists all over the world are fully engaged in finding a single mathematical formula or theory that explains every object and every phenomena occurring in the universe. Evolving superstring theory and M- theory are developments in that direction.
Space and time are the two most enigmatic elements in the universe. What we perceive with our senses as space and time is fundamentally wrong and our perception is just an illusion. Mathematicians and physicists aided by mathematics discern their properties and what they mean and how they behave. The basic attributes of space and time are that space is curved or/ and indented owing to the presence of massive bodies and time of moving bodies flows slower than that of bodies at rest.
In explaining the attributes of space, I must warn the readers at the outset that space is not like anything we think space is. We generally think of space as a complete vacuum or zero vacuum entity endlessly stretching in all directions. The informed readers are aware that waves of electromagnetic force, that is, photons are all-pervading and they are constantly moving at the velocity c until they are absorbed by some matters enhancing their energy. If we imagine that completely empty space is spread all over to infinity, light rays radiating from stars would have been fully sucked by that empty space beyond the boundary of our universe and never return. But observations by scientists confirm that light rays are being reflected. These findings lead to the realization that our universe must be cut off from the empty space, if there is anything like that. We mistakenly think of space as a stage on which all particles and massive bodies like stars and galaxies are going about their individual journey or are dancing to the tune of an invisible creator like actors perform on a stage their respective roles according to a script and under instructions of a director. Images of deep space received through satellite-based observatories confirm that the space we see or visualize has many properties unlike our mental picture. I wish to deliberate on the subject from philosophical point of view. Either God created the empty space or infinite space naturally exists for eternity. Why should God create empty space infinitely stretched in all directions whereas an infinitesimally small space (compared to infinite space) is used to accommodate this universe? Why should God create this universe in this particular place, not in other place? Why should empty space exist stretched to infinity in all directions whereas a very small fragment is necessary for this universe? Moreover, nature abhors redundancy. Even if we think there is infinite space outside our universe, it has no connection with our universe and our universe is completely cut off making it a self-contained and bounded one.
Some of the counterintuitive properties of space are described below.
1) Space is expanding. It does not mean celestial bodies like stars and galaxies are moving away from us or from one another. If it means that celestial bodies are moving away from us, the velocity of recession would have been the same for all heavenly bodies irrespective of their distance from us. Contrary to popular belief and imagination, the more distant a celestial body such as a star or a galaxy is from us, the faster is its velocity of recession. Direct observations prove beyond doubt that space is expanding meaning that every point or every cubic centimeter of space is expanding. As a result, cumulative effect of the expansion of space at every point propels all celestial bodies from us and away from one another at recession velocities directly proportional to the distance from us and away from one another.
2) Space is not continuous. Space is discreet or grainy in constituency. Scientists therefore use the term ‘fabric of space' to denote graininess.
3) Space is always seething with activities. Empty space is not empty. It has energy and as a result, particles and anti-particles are constantly forming and are immediately annihilated releasing energy.
4) The fabric of space is distorted due to movement of particles. In fact, space interacts actively with matter and energy and is warped or curved and indented in presence of or to accommodate massive bodies like the sun. This is one of the findings of Einstein's theory of relativity. Bending of light rays traveling near the sun was first demonstrated in an experiment conducted by British scientist Arthur Stanley Eddington sometime in the 1940s. Curvature of space is a reality that a pilot flying an airplane can only ignore at his own peril.
5) Space is not absolute. It is squeezed, dented like a well, curved due to the presence of massive bodies, and curved path or arc formed joining two points, which is part of the great circle, is the shortest distance between the two points, not the straight line. As space, all bodies, all matter and force particles are in a state of flux, there is no fixed frame of reference. Inside matter, molecules and atoms are constantly changing position and as such what we see as solid bodies at rest in fact move, albeit very slowly not visible through our naked eyes and decay over time.
Curvature of space is such a fundamental property of the universe that it needs elucidation so as to make readers understand its features. A few questions are naturally logical and relevant and needs be addressed. What does curvature of space mean? What are its attributes? How is it going to affect our understanding of the universe? Curvature of space is really a curved space. The mental picture about space that we have is that of a flat space. If we roll a piece of A4 size paper either length-wise or breadth-wise, the boundaries of both sides come closer and closer until they meet, making the shape of the piece of paper a cylinder. Latest observations confirm that the curvature actually leads to a complete bending round and closing up of space so that it becomes a domain of finite extent. For the purpose of our discussion, the closed space may be generally taken to be spherical. In a spherical space, if one goes on in the same direction, he will eventually come to the starting-point again. As there is no boundary, no point can be used to leave or enter a closed space. All these features constitute a self-contained finite universe. Perhaps the most fundamental characteristic of a spherical universe is that at great distances from us or any point, there is not so much room as we could have imagined. Let us take the example of the earth's surface. The surface area within two miles of say, GPO, Dhaka is nearly 4 (2x2) times the area within one mile. The surface area within 6,000 miles is considerably much less than 6000x6000 times the area within 1 mile. This could be easily visualized. Similarly, in 3-D curved space of the universe, the volume of space or amount of room within two light years (distance) of the sun is nearly 8 times the volume or amount of room within one light year. However, the volume or amount of room within 2 million light years is significantly less than 8 times of the volume within 1 million light years. The more distance we consider, the volume of space or amount of room will gradually diminish and the amount of diminution is inversely proportional to the distance.
In this context, I wish to refer to Stephen Hawking, who succinctly drew analogy of 2-D curved surface like the surface of earth to define the features of 3-D curved space. We know from observation what the characteristics of 2-D curved surface are. i) The curved surface is bounded and there is no edge or boundary and none can fall off the surface. ii) There is no vantage point or place that can claim that it is only at the centre. In fact, every place will find it is surrounded by equal number of places on all sides. iii) The centre of the 2-D curved surface is located nowhere on the curved surface, but somewhere on the third dimension. Similarly, the curved space of the universe is bounded; there is no edge or boundary and none can leave or enter the curved space. There is no special place; every star or galaxy is surrounded by equal number of stars or galaxies on all sides, and no star/ galaxy can claim any special position. The centre of the 3-D curved space will locate nowhere on the 3-D space, but somewhere on the fourth dimension. I have already explained how volume of space or amount of room diminishes in direct proportion to the distance from any point or star/ galaxy, and it holds good for every star/ galaxy.
As I am discussing time and its properties, the readers are advised to first accept the idea that time, like space is weird and counterintuitive. Like space, time is not absolute, it is variable. There are, however, some constants of nature. The most fundamental constant of nature is the velocity of light c, which is always constant, irrespective of the velocity of an observer or the source of light. As the velocity of light is constant and space is variable, time is also variable. Different observers in relative motion will keep different times. A simple calculation is laid down for more curious readers. Velocity of light c equals to distance light traverses divided by time a light ray takes. Distance is variable because of distortion, lengthening or squeezing of space and as such time can't be constant because in that case c will be variable, contradicting bed-rock principles of physics. Time slows down for an observer in motion relative to an observer at rest. Time-related equation in Einstein's special relativity very well establishes the relation how time elapses for different observers in relative motion.
Theoretical physicists have perhaps spent more time to demystify time than they have done to address other subjects. Julian Barber, a renowned physicist demonstrated in his book "The end of time' that passage of time is an illusion. The finding can simply result from the definitions of space and time and the equation of velocity, that is, v = dx/dt. What the equation is saying is that, if an object moves over any distance dx, there is an elapsed time dt. Since time is defined in physics as a parameter for denoting change (evolution), the equation for velocity along the time axis (not along space axis) must be given by v = dt/dt which is self-referential. The self-reference comes from the simple differential calculus that says dt/dt (differentiation of t with respect to t) always equals 1. To emphasize, it is logically impossible for the t coordinate of an object to change because such a change is self-referential. That means there is no time travel, no motion in spacetime.
The author has a Master of Science degree in mathematics and is a former Ambassador. He was associated with a large healthcare institution, a public-private joint venture in Bangladesh, as an adviser, which is spread all over Bangladesh and is second to the government in healthcare delivery. He authored a book entitled 'Africa- Through the Eyes of a Diplomat'. He regularly contributes stories, science articles and political developments to English dailies in Bangladesh.