Dark Matter Matters - Vera Rubin.

 

(Happy Birthday to astronomer Vera Rubin, born on this day in 1928!)

The periodic table of the chemical elements as we know it that dates back to the 19th century. So at the end of the 19th century, the understood theory of what the universe is made from is, there are more than a hundred different chemical elements. John Dalton, through his work on stoichiometry, concluded that each element of nature was composed of a single, unique type of particle. And thanks to this Dalton's atomic theory, what he said was that for every element like hydrogen, and helium, lithium and so on, there was an atom, which was thought to be something fundamental, indivisible, indestructible little thing and you had different atoms, one for every element. Then at the turn of the 20th century when the electron was discovered, that revised everything. During the same period, Einstein first suggested that the universe is dominated by gravity and there could be a “cosmological constant,” a kind of anti-gravity that pushes back to keep the universe static and prevent it from collapsing inward and then other people said that universe is expanding. In 1924, Edwin Hubble announced that we are not alone that the Milky Way is just one of many galaxies in the universe. Hubble measured the distances to galaxies and provided evidence for the expansion of universe. In the early 1930s, it was discovered that the nucleus itself is made of even smaller things called protons and neutrons. Inside the atomic nucleus, in the middle there are big heavy particles protons and neutrons stuck together by the nuclear force and there are electrons orbiting on the outside attracted to the nucleus by the electromagnetic force. So until the early part of the 20th century, it went with notion that the matter we see and most of the matter there in the universe would be protons and neutrons with accelerating electrons creating the light, but that came into question in the early 1930s; when Fritz Zwicky a Swiss astrophysicist at Caltech studied the Coma Cluster of galaxies located over 300 million light years away with an immense and home to thousands of individual galaxies spanning 25 million light-years in diameter. This was barely a decade after the realization that the Milky Way was not alone in the universe and numerous other galaxies exists as scattered throughout the cosmos. Zwicky looked at it in a number of ways, first he used galaxies motion to calculate mass and then he also used galaxies luminosity to calculate mass, his processes were not precise but they do provide approximate figures for the mass of the cluster. He noticed something funny about the way they moved that the galaxies in the coma cluster were moving far too fast, with only the gravitational effect of the galaxies in play each galaxy in coma should have been travelling sedately in its orbit. Zwicky reasoned that the individual galaxies in coma were held in their orbits by the gravitational pull of all the other galaxies around it. He realized that by measuring the galactic speeds he could determine just how much mass was in the coma cluster providing a new way of weighing the galaxies, but instead what Zwicky found was a big problem. And with immense speeds of almost a thousand kilometers per second, coma should have been tearing itself apart because all the stars in all those galaxies had far too little gravity to hold the cluster together, it was clear significantly more gravity was needed to hold coma together. Zwicky thought that something else must be biding them to each other. That mysterious missing component would have to weigh something like 50 times as much as the stars themselves. What was the source of this extra gravity with nothing obvious Zwicky concluded that there must be ‘duncal materi’ (meaning dark matter) that gravitationally binding the coma cluster and there had to be a lot more dark matter than the stars we can see.

Over the course of the 20th century, it became clear that there is much more to the universe than meets the eye. In 1933 Fritz Zwicky at Caltech, by studying the dynamics of clusters of galaxies, concluded that there is not enough visible matter in the galaxies to hold the clusters together gravitationally. He also pointed out that the measured quantity of luminous matter was far below the value that would be necessary for critical density—i.e., to produce a universe with an expansion that would gradually slow to a halt at infinity—but he speculated that the dark matter could conceivably be enough to make up the difference. Astronomers were faced with a stark question, is there an entire shadow universe of dark matter out there? What is it made from? And how can we measure it? Zwicky's discovery should have set the astronomy world on fire but because of his brusque style, no one paid much attention to this wild notion by considering it as just one of Zwicky’s crazy ideas and so instead there was silence. This was a shocking surprise and a lot of people didn’t believe it, because it is quite unnatural according to what their understanding about physics. This notion of dark matter lay buried in the pages of scientific journals and for the next few decades astronomers had a new focus measuring the expansion speed of the universe. By the 1970s there were new technological advances large telescopes and sensitive instruments for observing the heavens and with these a new generation of astronomers was asking new questions about the universe. The evidence for dark matter was growing and it was now they turned to Einstein's seemingly inconsequential theoretical prediction made more than half a century before; they turned to gravitational lensing. Rubin results were confirmed over subsequent decades by radio astronomers, the discovery of the cosmic microwave background, and images of gravitational lensing. And so Zwicky's dark matter was back in the spotlight, it was becoming clear that what we could see with our telescopes the myriads of stars and clouds of gas were nothing but minor cosmic players. Today many physicists continue to study the dark matter, using data from various telescopes and also Geneva where the Large Hadron Collider lurks underground, improving our understanding of particle physics. The cosmic pie depicts that ordinary baryonic matter, including everything made of atoms from the periodic table of which made all the galaxies, and stars, and planets in the universe; everything that Standard Model describes is just 5% of the total content of the universe. And more than five times of the known universe that we are made of; is the invisible dark matter stuff which is 27% of that cosmic pie, the matter that interacts with gravity but not light.

There are a number of different ways of working out how much dark matter is out there in the universe. So there is the gravitational lensing method which can be used across the whole sky and map the distribution of dark matter by how light is being bent through space and comparing it with the bending expected from the visible matter. In 2018 an enormous blue supergiant star nicknamed Icarus became the farthest individual star ever seen spotted by Hubble, formed nine billion years ago which existed four billion years after Earendel. The Hubble Space Telescope, 32 years after its launch, broke the all-time record for discovering most distant star substantially further away than Icarus. Just before its 32nd birthday Hubble spotted farthest star humanity ever seen “Earendel” setting its new record discovering fetching this star light from within the 1st billion years after the Big Bang appearing to us as it did when the universe was only 7 percent of its current age (at redshift 6.2). That is a dot of light that shone 12.9 billion years ago, or just 900 million years after the Big Bang. Earendel is only visible because of an intervening galaxy cluster WHL0137-08 creating the cosmic distorted lens in the space which magnifies the light, seen as the red arc named as 'Sunrise Arc' which represents the entire galaxy that Earendel is a part of. This find is a huge leap looking further back in cosmic time as the previous single-star record holder detected by Hubble in 2018 was an enormous blue star nicknamed “Icarus", existed when the universe was about 4 billion years old, or 30 percent of its current age. Until now, Icarus was the most distant single star on record, at a time that astronomers refer to as “redshift 1.5” and now we have Earendel at "redshift 6.2". Scientists use the word “redshift” because as the universe expands, light from distant objects is stretched or “shifted” to longer, redder wavelengths as it travels toward us. Hubble's observations of gravitational lensing effects have also given us a glimpse of the cosmos that will be unveiled by the James Webb Space Telescope. JWST may uncover objects from even earlier times in the universe’s history than what Hubble can see because this new infrared telescope will be sensitive to light from more distant objects. Upcoming wide-area surveys from the Vera Rubin Observatory and Euclid combined with detailed follow-up from James Webb Space Telescope will provide a revolution in the understanding of early universe. One of the scientific goals of the Vera Rubin Observatory is to study the dark energy and dark matter by measuring weak gravitational lensing, baryon acoustic oscillations and photometry of type Ia supernovae, all as a function of redshift. Similarly, the objective of the Euclid, visible to near-infrared space telescope is to better understand dark energy and dark matter by accurately measuring the acceleration of the universe.

Earendel is positioned along a ripple in space-time, massive galaxy cluster which bend and focus the light from more distant background objects and so Earendel gets extreme magnification, allowing it to emerge into view from its host galaxy, which appears as a red smear/arc across the sky. The Hubble Frontier Fields observing campaign drew upon the power of massive clusters of galaxies to unleash the full potential of the Hubble Space Telescope. Hubble's sensitivity and high resolution allow it to see faint and distant gravitational lenses that are harder to detect with ground-based telescopes. Gravitational lensing is a phenomenon created by extremely concentrated masses like the galaxy clusters. Their strong gravity warps the surrounding space, and light from distant objects travelling through that warped space is curved away from its straight-line path, as if passing through a lens. Hubble can resolve details within the multiple banana-shaped arcs that are one of the main results of gravitational lensing as the images of background sources are distorted. An important consequence of lensing distortion is magnification, allowing us to observe objects that would otherwise be too far away and too faint to be seen. Hubble makes use of this magnification effect to study beyond the sensitivity of its 2.4 meter diameter primary mirror by showing us the most distant galaxies/stars humanity has ever encountered. Einstein's notebooks indicate that he had realized that if an observer was located at the correct distance, the deflected light rays from around the celestial object would converge to make a magnified image. This phenomenon is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein's general theory of relativity that light should be bent by gravity.

This is the First Deep Field image from NASA’s James Webb Space Telescope. It is the deepest and sharpest infrared image of the distant universe to date, looking far back in time when the Universe was less than a billion years old. This Webb’s First Deep Field image is covering a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground and yet overflowing with detail as it reveals thousands of galaxies – including the faintest objects ever observed in the infrared – have appeared in Webb’s view for the first time in this tiny sliver of vast Universe. It shows galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago, with many more galaxies in front of and behind the cluster. There are stars, the things with the kind of cross twinkie patterns. But everything else, pretty much, is a galaxy. These are extremely distant galaxies, sort of almost out to the edge of as far as we can see with telescopes. So, for example, in the center of the image, you can see there's a kind of cluster of galaxies, kind of blobs. Now, hopefully you should be able to also see that on this image, there is this smearing pattern. So there's kind of circular structures arranged around this central cluster of galaxies. Multi-wavelength studies have led to the discovery of numerous new objects in space & have allowed us to "see" the Universe as never before. With advances in technology & the ability to place telescopes into space, we can now see the Universe in all of its light! All the wavelengths of the electromagnetic spectrum have something important to say. We can learn from each wavelength, by observing the Universe in a various wavelengths of light to understand the complete picture. Multi-wavelength astronomy fetch us complete picture of the universe as observing it in different wavelengths from radio, microwave, infrared, optical, ultraviolet, x-ray to gamma rays. Since the Webb's successful launch last year, now we have multi-wavelength composite images from Webb and NASA’s great observatories at various wavelengths. Chandra is an incredible piece of equipment and it is part of a suite of other observatories so called NASA's great observatories which includes Hubble, Spitzer and the Compton gamma-ray observatory. Webb Deep Field shows how galaxy cluster SMACS J0723, located ~4.2 billion light-years away, contains hundreds of galaxies. Galaxy clusters are filled with vast reservoirs of superheated gas seen only in X-ray light. In the same image later Chandra data (blue in color) revealed gas with temperatures of tens of millions of degrees, possessing a total mass about 100 trillion times that of the Sun. Invisible dark matter forms an even larger fraction of the cluster’s total mass compared to the measured quantity of luminous matter.

Gravitational lensing basically acts like a lens and we end up getting this kind of smeared multiple image of the same galaxy across the whole sky, which you can see in the JWST’s first image so called Webb Deep Field. Why do some of these galaxies in this image appear bent? This smearing is something called gravitational lensing. The combined mass of this galaxy cluster acts as a gravitational lens magnifying more distant galaxies, including some seen when the Universe was less than a billion years old. So this is essentially where light from a distant galaxy travels towards the earth. Now thanks to Einstein, we know that gravity doesn't just make matter move in orbits or curves. It also curves space time, and it will cause light to travel in curved paths. As the light leaves the galaxy and travels past this heavy object (galaxy cluster between JWST and the distant galaxy), it get bent by cluster gravity and pulled back towards the JWST again. So we have evidence of dark matter from lensing and also by looking at the rotations of stars around galaxies, we can calculate to a fairly high degree of confidence how much dark matter is out there, even though we can't see it which Vera Rubin famously studied in 1970s. Vera Rubin was an American astronomer who pioneered work on galaxy rotation rates. She targeted the large spiral galaxies similar to our own milky way, working with her collaborator Kent Ford she wanted to understand how these galaxies spin. Vera Rubin in the 1970s was looking at Andromeda and the other neighboring galaxies; she measured the rotation speeds of the stars in those galaxies. The expectation was that these galaxies were like the solar system with most of the mass concentrated towards the center. So closer to the center of the galaxy you have lots of gravity and the stars should be orbiting very quickly in order to not fall into the center and just like the planets the speeds of stars in the spiral disk were expected to fall as gravity gets weaker towards the edge of the galaxy, but this was not what Rubin found. The rotation speed of stars did not diminish but remained roughly the same all the way to the edge of the galaxies. She uncovered the discrepancy between the predicted and observed angular motion of galaxies by studying galactic rotation curves. Identifying the galaxy rotation problem, her work provided the first evidence for the existence of dark matter.

Vera Rubin did some pretty incredible things as helping to prove the existence of dark matter. She uncovered the discrepancy between the predicted and observed angular motion of galaxies by studying galactic rotation curves. She used calculations to show that galaxies contain at least five to ten times more dark matter than ordinary matter which is really considered as one of the biggest and most important discoveries in astronomy, an early indication that spiral galaxies were surrounded by dark matter haloes. Rubin's results were confirmed over subsequent decades, and became the first persuasive results supporting the theory of dark matter, initially proposed by astronomer Fritz Zwicky in the 1930s. Vera Rubin was the first woman in 1965 to use the telescope at the Palomar Observatory which was the biggest telescope in the world at the time and this was a major step because before that women weren't allowed to do that. It was incredible that she finally had that dare, her want to use the biggest telescope in contemporary period and we are overcompensating for something with this giant telescope as she really had to work hard to get to that point. She was born in 1928 when a scientific field certainly dominated by men. Her career before even getting to that position was quite an inspirational journey, at first she wanted to do her degree in astronomy and for her Bachelor of Science degree most schools wouldn't accept her but finally she got into an all-girls school and graduated. She was the only one from her class who graduated with a degree in astronomy. And then she went to Cornell, again most other universities wouldn't accept her into their program because she was a woman. So for her to get to where she was required some kind of tenacity, at age 23 she started pursuing her PhD and she even had her first child while pursuing her PhD. She had entered astronomy when it was essentially a male-only activity and encountered resistance throughout her career including a lack of female bathrooms in the telescopes facility she used, but this didn't stop her as she undertook meticulous observations of the rotation speeds of spiral galaxies. This terrific and well-deserved gutsy woman will be the first woman to have an observatory named after her. On December 20, 2019, the Large Synoptic Survey Telescope (LSST) was renamed the National Science Foundation Vera C. Rubin Observatory in recognition of Rubin's contributions to the study of dark matter and her outspoken advocacy for the equal treatment and representation of women in science. It has the current most powerful telescope in the world with the largest (human sized) digital camera ever built, designed to take continuous 24-hour increment snapshots of the sky which then can be stitched together to make a movie of the night sky. Hence previously referred as the ‘Large Synoptic Survey Telescope’ (LSST) which itself evolved from the earlier concept of the ‘Dark Matter Telescope’. The name honors Rubin and her colleagues' legacy to probe the nature of dark matter by mapping and cataloging billions of galaxies through space and time. The observatory will be located on a mountain in Cerro Pachon, Chile and focus on the study of dark matter and dark energy. It will also contribute to the study of the structure of the universe by observing thousands of supernovae, both nearby and at large redshift, and by measuring the distribution of dark matter through gravitational lensing.

Vera Rubin in the 1970s was looking at Andromeda and the other neighboring galaxies; she measured the rotation speeds of the stars in those galaxies. When we map the velocity of the planets orbiting the Sun because the Sun has 99% of all the matter in the system, the mass within any orbit will be relatively fixed at the sun's mass. Therefore the further away from the central mass we get the weaker the gravitational pull and the slower the orbital velocity this model is called Keplerian model because it follows Kepler's laws for orbital motion. Vera Rubin published a paper in 1978 studying the rotational velocities of stars in galaxies as a function of their distances from the galactic center. The expectation was that these galaxies were like the solar system with most of the mass concentrated towards the center. So closer to the center of the galaxy you have lots of gravity and the stars should be orbiting very quickly in order to not fall into the center and just like the planets the speeds of stars in the spiral disk were expected to fall as gravity gets weaker towards the edge of the galaxies, but this was not what Rubin found. Rotational velocities were found to be nearly constant over a fairly large radial distance, though predictions based on the distribution of visible matter implied that they would decrease with distance. The rotation speed of stars did not diminish but remained roughly the same all the way to the edge of the galaxies. Just like Zwicky, she was left with a gravitational puzzle that what was the source of gravity needed to keep the stars moving at their unexpected speeds. So again to explain that motion you need to invoke some invisible material that adds an extra gravitational attraction to hold the stars in the galaxy. Rubin’s discoveries were interpreted as evidence for the presence of substantial amounts of dark matter in the haloes around galaxies. And we can use that again to measure how much dark matter there is in the galaxies as her data was confirmed by radio astronomers, the discovery of the cosmic microwave background (CMB), and images of gravitational lensing. About the same time, radio astronomers, using a spectral line of hydrogen at 21-cm wavelength, obtained a similar result in the outer parts of galaxies where there is little starlight. Using accurate and high-resolution emission lines from neutral hydrogen astronomers modeled the mass distribution of galaxies. They use the mass-to-light ratio in the visible disc; a galaxy's core radius and the circular velocity of the halo. The study found the contribution to the rotation curve of three types of matter gas, luminous matter and dark matter. This new understanding about the possibility and impact of dark matter, astronomers turn their attention back to galaxy clusters like the one studied by the Zwicky in 1936. Dark Matter makes up most of the mass of galaxies when they've looked at the speed and rotation of galaxies where there should be less Mass on the outside and they should be slowing down in fact the galaxies were spinning really fast too fast so either we have missed some fundamental calculations in the universe or there's just mass invisible to the telescope.

The solar system is located within the Milky Way Galaxy, close to its equatorial plane and about 8 kiloparsecs from the galactic center. The galactic diameter is about 30 kiloparsecs, as indicated by luminous matter. There is evidence, however, for nonluminous matter so called dark matter extending out nearly twice this distance. The entire system is rotating such that, at the position of the Sun, the orbital speed is about 220 km per second (almost 500,000 miles per hour). But even at this speed, it takes about roughly 240 million years for the Sun to make one complete trip around the Milky Way. Application of Kepler’s third law leads to an estimate for the galactic mass of about 100 billion solar masses. The rotational velocity can be measured from the Doppler shifts observed in the 21-cm emission line of neutral hydrogen and the lines of millimeter wavelengths from various molecules, especially carbon monoxide. At great distances from the galactic center, the rotational velocity does not drop off as expected but rather increases slightly. This behavior appears to require a much larger galactic mass than can be accounted for by the known (luminous) matter. Additional evidence for the presence of dark matter comes from a variety of other observations. The nature and extent of the dark matter (or missing mass) constitutes one of today’s major astronomical puzzles. We also have evidence of dark matter from simulations which show how the universe formed in the early stages. And essentially what scientists find that if we want to show how structure in the universe formed, we need dark matter. If we don't put dark matter into your simulations, then we don't get the universe that looks like the one we live in. So for the simulation that can show the sort of galaxies bursting to life and new stars turning on, we need the dark matter to make this work, and to agree with what universe we observe out there in the sky.

One more way of measuring the dark matter is by looking at something called the Cosmic Microwave Background (CMB) which is a very faint microwave radiation left over from the big bang, essentially the point about 380,000 years after the big bang. The universe before that point was massive super-heated opaque plasma. At 380,000 years it expanded and cooled down enough, so that plasma condensed into a gas and light, for the first time could travel freely and that light has been basically travelling through space ever since which we now detect as CMB radiation. The Cosmic Microwave Background (CMB) is microwave radiation that fills the all space in the observable universe and can be detected in every direction. With a standard optical telescope, the background space between stars and galaxies is almost completely dark. However, a sufficiently sensitive radio telescope detects a faint background glow that is almost uniform and is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. As microwaves are invisible to the naked eye, we can’t see it but it is everywhere in the universe and cannot seen without instruments as a static signal on the screen. Because this pattern is everywhere we look, the source of this background (CMB) is bath of photons coming uniformly from every direction in the sky. And by looking at patterns in this radiation across the whole sky, we can calculate again how much dark matter there is in the universe. It is a remnant that provides an important source of data on the primordial universe. Dr. John C. Mather is a senior Astrophysicist in the observational cosmology laboratory at NASA’s Goddard Space Flight Center. He is also the Senior Project Scientist on the James Webb Space Telescope. He has received many awards including the Nobel Prize in Physics, 2006, for his precise measurements of the cosmic microwave background radiation using the COBE satellite. In 1978, Nobel Prize for Physics was awarded to American radio astronomers Arno Penzias and Robert Wilson for detecting the CMB back in 1965. The accidental discovery of the CMB in 1965 by Penzias and Wilson was the culmination of work initiated in the 1940s. After couple of decades, John Mather and George Smoot shared the 2006 Nobel Prize in Physics, the pair were honored for their “discovery of the blackbody form and anisotropy of the cosmic microwave background radiation” measured by COBE. Further evidence for dark matter comes from measurements on cosmological scales of anisotropies in the cosmic microwave background. The distribution of the anisotropy across the sky has frequency components that can be represented by a power spectrum displaying a sequence of peaks and valleys. The peak values of this spectrum hold important information about the physical properties of the early universe: the first peak determines the overall curvature of the universe, while the second and third peak detail the density of normal matter and so-called dark matter, respectively. The height of the second peak implies that 5% of the total is ordinary atoms, while matching all the peaks implies that 26% of the total is dark matter. Indeed the CMB by itself provides irrefutable evidence for dark matter. So all of these three methods gives us answers about the existence of ‘dark matter’ in the universe.

Euclid space telescope was successfully launched on 1st July 2023, beginning its mission to study dark energy and dark matter in the universe. It is a fully European mission, built and operated by ESA, with contributions from NASA. Euclid is designed to explore the evolution of the dark Universe; it will take images in optical and near-infrared light. The telescope will create the largest-ever 3D-map of the Universe (with time as the third dimension) by observing billions of galaxies out to a distance of 10 billion light-years away, across more than a third of the extragalactic sky outside the Milky Way. Mapping the extragalactic sky over six years will provide unprecedented data to give new insight on the nature of dark energy and dark matter, helping scientists unravel the mysteries of the 'Dark Universe.' Euclid’s image quality will be at least four times sharper than that achieved by ground-based sky surveys. Textbooks and popular accounts universally claim that Einstein was the first to equate the geometry of a flexible spacetime (placed on the left side of his field equations) with the matter affecting that geometry (placed on the right), demonstrating the revolutionary idea that mass and geometry are intimately connected. Euclid is named after the Greek mathematician Euclid of Alexandria, who lived around 300 BC and founded the subject of geometry. As the density of matter and energy is linked to the geometry of the universe, the mission was named in his honor. A whole host of experiments are underway with many more planned for the immense telescopes that are currently making their way from drawing board to reality. In Chile, the 8.4 meter telescope at the Vera Rubin observatory will turn its eye to the sky in 2024. So if we get more and more galaxies then we get a more and more accurate map of where that dark matter is and what it looks like. One of the scientific goal of the upcoming Vera Rubin Observatory is to study the dark energy and dark matter by measuring weak gravitational lensing, baryon acoustic oscillations, and photometry of type Ia supernovae, all as a function of redshift. Similarly, the objective of the Euclid, visible to near-infrared space telescope is to better understand dark energy and dark matter by accurately measuring the acceleration of the universe. Euclid is a cosmology survey mission, optimized to determine the properties of dark energy and dark matter on universal scales. When we see today the structure of the universe as we know it, that has all sorts of galaxies populating this cosmic web of structure and this diffuse light that's out there today came from all sorts of interactions happened during the early history of the evolution of galaxies. While dark energy accelerates the expansion of the Universe and dark matter governs the growth of cosmic structures, scientists remain unsure about what dark energy and dark matter actually are. By observing the Universe evolving over the past 10 billion years, Euclid will reveal how it has expanded and how structure has formed over cosmic history – and from this, astronomers can infer the properties of dark energy, dark matter and gravity, to reveal more about their precise nature. The key goals of these and other telescopes is to uncover the mysteries of dark matter and dark energy which includes searching for the signs that dark energy might not be exactly Einstein's cosmological constant perhaps dark energy has evolved and changed over the billions of years of the universe maybe it has decayed into matter and radiation. These would provide new clues to the true nature of dark energy and open new avenues of research to unravel its physics. However as of today all observations suggest that dark energy appears to be precisely Einstein's cosmological constant unchanging over the life of the universe, but this sends a shiver down the spine of cosmologists as it might mean that the cosmological constant is uncrackable. The nature of dark matter and dark energy represents a failure of the fundamental laws of physics. European space agency has launched its Euclid telescope on a mission to produce an enormous 3D map of the cosmos designed specifically to give us important new insights into the "dark side" of the universe -- namely dark matter and dark energy.

The dark sector could potentially host its own physics as rich as those in the atomic world, but with the limited observational evidence we are again stuck in the world of theory and clearly more observations and measurements are required. Whilst astronomers were gazing skyward, particle physicists were hunting for dark matter in the world of the subatomic realm. Through the course of the 20th century, they had unraveled the fundamental nature of matter finding the particles from which mass and forces are constructed, comprised of quarks and leptons, photons and gluons as well as the more esoteric w and z bosons. This zoo of particles was rounded off in 2012 with the discovery of the Higgs boson. This standard model of particle physics has proved to be a great success, it accurately accounts for the tumult of particles pouring out of the immense collisions at the large hadron collider and other particle physics experiments. Scientist believes that Standard Model is definitely on to something as you don't get this kind of result by accident. Despite this we know it must be incomplete as it can account for the strong and weak nuclear forces and electromagnetism but gravity is still resisting from being added to the quantum world. So it’s a really stunningly successful theory, but it is not without some problems. And these problems are actually what motivated, in part, the building of the Large Hadron Collider in the first place. There are at least two key components of our cosmos that are missing from the standard model of particle physics. Scientists aim to find out more about two of the universe's greatest mysteries: dark energy and dark matter, researchers know virtually nothing about these phenomena which appear to make up the vast majority of the universe. The discovery of the Higgs which is really kind of closing the chapter of 20th century physics and the beginning of the next era in fundamental physics paving the way to new physics. What everyone now actually is after the answers to some big, unsolved questions that the Standard Model cannot address. The cosmic pie depicts that ordinary matter of which made all the galaxies, and stars, and planets in the universe; everything that Standard Model describes is just 5% of the total content of the universe. And more than five times of the known universe that we are made of; is the invisible dark matter stuff which is 27% of that cosmic pie. There is something even more mysterious called dark energy that’s makes up around 68% of cosmic pie, repulsive force that appears to be accelerating the expansion of the universe. That's pretty big of what's out there, so that is definitely a bit of an omission in the Standard Model. The large hadron collider at CERN had remained shut for three years as scientists worked on upgrading the facility for higher proton collisions than in 2012 when the God Particle was discovered, the detectors, electronics, and computing have all gone through substantial upgrades. Scientists are not done, Large Hadron Collider was not built to just find the Higgs boson; it was built to find new particles. LHC was shut down for maintenance purpose just before the start of Run 3, they tightened the screws once again as they are going to lift it up to a much higher energy. The changes will allow them to collect significantly larger data samples, of higher quality than previous runs. The restart marked the beginning of preparations for the third run of the LHC, called Run 3, which planed four years of physics-data taking at world-record collision energy of 13.6 trillion electronvolts (13.6 TeV). LHC Run 3 was started on 5 July, the day after the 10th anniversary of the discovery of the Higgs boson. There are also theoretical hints that the new physics should be found at accessible energy scales. Much of the efforts to find this new physics are focused on new collider experiments. LHC Run 3 with the increased data samples and higher collision energy expanded further the already very diverse LHC physics programme and now scientists at the LHC experiments will be searching for candidates for dark matter and for other new physics phenomena, either through direct searches or – indirectly – through precise measurements of properties of known particles and these more powerful collisions will allow us to explore further the particle world, and we will certainly learn much more.

The discovery of the Higgs was such a big deal and now that we have found it, we can move beyond everyday physics, there are dark matter, dark energy and black holes out there in the universe. Particle Physicists are hopeful that the Higgs boson will not simply be the end of one story, but the beginning of the next era in fundamental physics. So the next question: Is there any boson for gravity? And basically if there is no boson for gravity, how could we explain it? It is hypothesized that gravitational interactions are mediated by an as yet undiscovered elementary particle, dubbed the graviton. In theories of quantum gravity, the graviton is the hypothetical quantum of gravity, an elementary particle that mediates the force of gravitational interaction. There is no complete quantum field theory of gravitons due to an outstanding mathematical problem with renormalization in general relativity. If it exists, the graviton is expected to be massless because the gravitational force has a very long range, and appears to propagate at the speed of light. General relativity did give scientists a nice starting point. According to general relativity's explanation of the distribution of the mass and energy in the universe, if there is a graviton it's a massless particle with the spin of two; scientists from Fermilab and CERN are looking for this particle with eager eyes. Assuming that they do exist, it would be a bit unlike the other particles. The problem with gravitons is that gravity is so weak; while gravitons offer a nice explanation of gravity, we are yet to discover their existence. So what exactly is it about graviton that makes it so hard to discover? You see gravity contrary to what many people believe is one of the weakest forces to exist. If we go down to particle level, we have got these incredibly strong forces of nature that are mediated by elementary particles like the electromagnetic force by the photon, the strong nuclear force by gluons, the weak force by the W and Z bosons and they totally overwhelm gravity; in fact the bonds holding together a hydrogen atom are stronger. To prove this just think how easily we can pick up an apple despite the entire earth exerting a gravitational pull on it. From a quantum mechanical view the reason for gravity's lack of strength is due to the fact that gravitons interact very weakly, so as a result detecting a graviton would be very difficult. It’s quite difficult to actually measure their effect, so if you are trying to do some experiment to measure gravitational attraction between two particles then that attraction is so tiny that it's basically impossible to measure in an experiment at the moment. The cosmic pie depicts that ordinary baryonic matter, including everything made of atoms from the periodic table of which made all the galaxies, and stars, and planets in the universe; everything that Standard Model describes is just 5% of the total content of the universe. And more than five times of the known universe that we are made of; is the invisible dark matter stuff which is 27% of that cosmic pie, the matter that interacts with gravity but not light. And if you really want to find the evidence of gravitons then you have to build a gigantic particle accelerator that the size of the Milky Way galaxy. So scientists don’t have any firm evidence for their existence, but still they think that gravitons are out there.

People: What is dark matter?

Scientists: ¯\_(ツ)_/¯

It’s not the thing that bothers what came first; chicken or eggs?

But the biggest curiosity quest is dark matter with the boson Higgs.

It’s kind of assumed that at the moment, they are impossible to detect directly but some of these extra dimensional theories contain massive gravitons in them. And those are things that could be observe in a collider, so if some of these extra dimensions of space ideas are right then there could be gravitons that can be detectable by the LHC. So far we know that 95% of the universe is dark it doesn't shine. We have constructed what seems to be this stunningly successful theory over a century with all these clever experiments backing it up. But then we realize that what we've been describing is actually only a tiny fraction of the total content of the universe. And as having a theory that works really well in the very narrow domain in which we've applied it, but tells us basically nothing about major content of the universe. In the physics community, until we find and confirm the existence of gravitons they just remain theory explanation of our universe. So the lesson from this is essentially that the word “dark” in physics means we don't know what we're talking about and that scientists themselves get very suspicious because it as we cannot see it with our telescopes. Although dark matter does not interact with light, it interacts with gravity. So we observe it through its influence on other things using methodology called weak gravitational lensing where the shapes of distant galaxies gets distorted as the light from them comes to us by passing through the Dark Matter in between. Today many physicists continue to study the dark matter, using data from various telescopes and also Geneva where the Large Hadron Collider lurks underground, improving our understanding of particle physics.

 

 

CERN Concern…

↓↓↓↓Poetic Piece↓↓↓↓

http://sukalyogesh.blogspot.com/2023/06/cern-concern.html

CERN Concern...

 

 

 

The Biggest Curiosity Quest?

What Came First?

Chicken or Eggs?

What about Higgs?

What Came First?

Field or Boson?

Give Science a Test,

Not a Big Concern,

We do have LHC at CERN,

And Learned Lesson,

That there is more,

And more to Learn,

Well, Science is Fun,

Give LHC few more Run,

We have History to Remake,

After all, LHC is “A Piece of Cake”.

Since the 19th century physics has been trying very hard to find the elementary particles, the fundamental building blocks of nature. Today it's the job of particle physicists who literally study the building blocks of nature and their properties. Speaking of which CERN is the European Organization for Nuclear Research just outside Geneva. It is kind of wonderland for particle physicists as there are thousands of physicists from around the world who are involved in research there. It's got everything that a small town should have like restaurants, a post office, travel agents, hotels. It's a kind of town populated exclusively, though, by particle physicists. Particle physics is a thriving field that gave us understanding that objects around us are made of atoms which in turn are made of subatomic elementary particles. The idea that all matter is fundamentally composed of elementary particles dates from at least the 6^th century BC. Democritus was the guy who really pushed an idea that his predecessor didn't write anything and publish or perish in the academic world. Democritus was an ancient Greek philosopher and a true scientist, 2,500 years ago he had the idea that the world is made of countless indivisible particles in a void. The word atom, after the Greek word atomos meaning "indivisible", Democritus was the first to print the idea that the world is made of atoms what we would now call elementary particles. Democritus had the idea that you see a bunch of things around as liquids like water, solids like wood, you see air are the substances that appear very different with different properties, they look different, they react differently and yet they are not fundamentally different but just different arrangements of the same underlying thing called atoms. Ancient Greeks would have thought these were all fundamentally different things, but the atomists like Democritus had this astonishing idea about the way the world works. Today, particle physicists are driven by the same impulse as the Democritus. Even though atoms weren't truly elementary that he was on the right track and it took a long time to get that idea right, it turns out to be right and so particle physicists now are the intellectually descendant of Democritus's ideas that we call as particle physics. He was a man with passionate desire to know the Cosmos, scientists give him credit for launching the bandwagon we currently knows particle physics and so essentially Democritus was the first theoretical particle physicist or the father of particle physics. Since then atoms are denoted as the smallest particle of a chemical element, but physicists soon discovered that atoms are not, in fact, the fundamental particles of nature, but are conglomerates of even smaller particles.

 

  

 

The periodic table of the chemical elements as we know it that dates back to the 19th century. So at the end of the 19th century, the understood theory of what the universe is made from is, there are more than a hundred different chemical elements. John Dalton, through his work on stoichiometry, concluded that each element of nature was composed of a single, unique type of particle. And thanks to this Dalton's atomic theory, what he said was that for every element like hydrogen, and helium, lithium and so on, there was an atom, which was thought to be something fundamental, indivisible, indestructible little thing and you had different atoms, one for every element. Then at the turn of the 20th century when the electron was discovered, that revised everything. In the early 1930s, it was discovered that the nucleus itself is made of even smaller things called protons and neutrons. Inside the atomic nucleus, in the middle there are big heavy particles protons and neutrons stuck together by the nuclear force and there are electrons orbiting on the outside attracted to the nucleus by the electromagnetic force. And so we got the model of the atom that we all learn about in school, which is a positively charged nucleus which contains most of the mass of the atom around which go these electrons.  Now, if you look at the periodic table in the way that the elements were arranged, there are certain patterns in the properties of the different chemical elements as the way they are arranged. They get more reactive as you go down and that was sort of indication of some deeper structure. So essentially you can explain the properties of all these different elements by different numbers of electrons going around the outside of atoms. The electrons are what determine the chemical properties of that particular element. The proton is positively charged while the neutron is electrically neutral; these nucleons are much heavier or massive than electrons. We thought these were elementary but turns out that they're not; science did not stop there and discovered more particles as you zoom into the nucleus, even protons and neutrons are made of smaller particles called quarks. In the 1960s, theoretical physicists were working on an elegant way of describing the fundamental laws of nature in terms of quantum field theory. It was really in the 1970s that the search for the Higgs boson began in earnest, the 1970s were an era when quantum field theory really became triumphant. In the 1960s and even before that all the way back to the 30s scientists had ideas of quantum field theory, but it wasn't until the late 1960s and early 1970s that scientists realized that this was the right way to think about nature at a fundamental level. In quantum field theory, both matter particles (fermions such as electrons, or the quarks inside protons) and the force carriers (bosons such as the photon, or the gluons that bind quarks) are manifestations of underlying, fundamental quantum fields. We also have neutrinos and muons; so there is a whole zoo of elementary particles and particle physicists really tried to figure out what all these particles were and how they all fitted together in terms of the model. Today we call this elegant description the Standard Model of particle physics.

 

  

 

The matter particles in the universe called fermions and there are force carrying particles called bosons. The Standard Model describes three of the four fundamental interactions in nature; only gravity remains unexplained. In the Standard Model, such an interaction is described as an exchange of bosons between the objects affected, such as a photon for the electromagnetic force and a gluon for the strong interaction. Those particles are called force carriers or messenger particles. Neutrinos are sort of like ghosts as they are invisible, almost undetectable particles and they very rarely interact with the ordinary matter that we're made out of. So that's why we are not really that aware of the existence of neutrinos most of the time. There are trillions of them go straight through you, straight through the earth as they are produced by the sun in vast quantities. Muon is a sort of heavy cousins of electron which is about 200 times more massive than the electron. Also the reason we're not made of muons because it decays into an electron and some neutrinos. They're unstable, but you can make them in high-energy collisions like at the LHC. Gluons are kind of force particles that bind protons and neutrons together and hence called a gluon because it glues things, essentially. So there is a whole zoo of elementary particles. The four matter particles are neutrino, the down quark, the up quark and the electron. For particles that makes up matter turn out to be a single family of particles but then there are three generations of matter particles as the same pattern repeated three times that little bit is a mystery. On top there are bosons and then way up all by itself in the corner there's this lonely little thing called the Higgs boson. As a new particle and that thing, ripple in the Higgs field gives mass to the particles which we are made of, at least, is this field. And the Higgs boson really is the proof that this field is out there. And that's why finding it was so important, because the Higgs mechanism; the process by which the particles get mass is absolutely fundamental to the Standard Model. It's kind of like the keystone in an arch.

 

 

So what’s about the Higgs? It’s not the biggest curiosity question that what came first, chicken or eggs? But what came first the Higgs field or Higgs boson? In the Higgs boson's case, the field came first. Fundamentally speaking what gives you mass is a very different question to what gives you weight. Gravity pulling down on your body gives you weight and your weight can change depending on the gravity of the planet that you are on, even though you're so made of the same amount of stuff that we call as a mass. Before Newton’s contribution, most previously known forces arose when two objects pushed or pulled each other via physical contact, whereas Newton’s gravitational force evidently operated across great voids of empty space. Over the next two centuries after Newton, such concerns gave rise to the notion of a space-filling field, which can be imagined as the medium that transmits the message. By the 1840s, however, the creators of hydrodynamics were treating fluid properties—velocity, density, pressure—as fields. Hydrodynamic concepts, in turn, soon provided the basis for the 19th century’s most celebrated field theory, the electromagnetism of James Clerk Maxwell. Today no one doubts the reality of fields; anyone who has sprinkled iron filings on a piece of paper above a bar magnet has perceived a field pretty directly. Back then, the existence of fields was less obvious. More precisely, a field is a continuous and continuously varying plane of action through which disturbances propagate, eliminating the conceptual knot of “action at a distance.” The idea of modern physics is that the world is not made of particles but it's made of fields, a field unlike a particle is spread out everywhere throughout the universe. That there is a field filling the universe and what that means mathematically just that at every point in space; there is a number at every point in space and time, the value of the field just like the temperature of the air in this room and every point there's a value the temperature at that point of the air but this is not some phenomenology of the matter this is this a fundamental feature of reality. The most familiar example of this is light: light is simultaneously a wave in the electromagnetic field and a stream of particles called photons. Photon is the particle of light that transmits the electromagnetic interaction, so light itself is also an electromagnetic phenomenon. Very much similar to our current description of Nature, every particle is a wave in a field. The Higgs field was proposed in 1964 as a new kind of field that fills the entire Universe that gives mass to all elementary particles. The Higgs boson is a wave in that field. On July 4th 2012, CERN scientists announced that experiments at the Large Hadron Collider discovered the Higgs boson that Peter Higgs predicted back in 1964; this discovery was a massive worldwide media sensation. The existence of this mass-giving Higgs field was confirmed in 2012, when the Higgs boson particle was discovered at CERN. Particles get their mass by interacting with the Higgs field; they do not have a mass of their own. The stronger a particle interacts with the Higgs field, the heavier the particle ends up being. Photons, for example, do not interact with Higgs field and therefore have no mass. Yet other elementary particles, including electrons, quarks and bosons do interact and hence have a variety of masses. Peter Higgs and his colleagues with whom he was working with roundabout the same time essentially said that imagine that throughout the entire universe there is an additional cosmic quantum field and just like the other fields that these massive particles are ripples move through it. Higgs bosons are these things that scientists think are massive and are imbued with mass by Higgs field. Back in the 1960s, Scientist had the idea of the Higgs boson but they hadn't actually seen evidence for it. So Peter Higgs went back to his paper and he said, well, I need to connect this with something that could be experimentally measured. And what he added to his paper was basically one line that said, if this cosmic energy field that gives mass to all the particles exists, then you should be able to create a ripple or a disturbance in it which would show up. Because it can be used to pretty much explain all the physics that we can see around us as some scientists think that it's the closest we have to a “theory of everything”. So we can use this science in principle to describe everything from how a light bulb produces photons to how atoms are fused together inside stars. And as we know how the formation of stars then caused a tremendous ripple effect and helped shape the universe as we know it. Heat within the stars caused the conversion of helium and hydrogen into almost all the remaining elements in the universe. In turn, those elements became the building blocks for planets, moons, life, everything we see today. This ecosystem of everything was only possible because of the many stages in the universe’s development. While countless questions about the origins of our universe remain, it’s only a matter of time for some long-sought answers to emerge.

 

 

Peter Higgs wrote his paper in early 1964, he had this idea which was written down with very elegant mathematics. The Higgs field named after him, although many others contributed to the idea. And this theory is really a kind of incredible achievement as this was not the idea of a single lone genius like Einstein but democratic idea as it took many sociable geniuses to put this idea together. So the next step was to actually look for it because it's very nice to have a theory that fits together and makes sense, but we really want to get the direct evidence that they were on the right track. In particle physics that means building new more energetic, more powerful particle accelerators. The Higgs boson can't be “discovered” by finding it somewhere but has to be created in a particle collision. Once created, it transforms – or “decays” – into other particles that can be detected in particle detectors. This is a really the way that particle physics gets its direct evidence by Einstein's famous equation (E=Mc2) relating the energy of an object at rest to its mass times the speed of light squared. It's the energy a particle has when it's not moving, so it enables us to bring into existence new particles with heavier masses than before if we can squeeze a lot of energy into a very tiny amount of space. So that's what a particle accelerator does, it accelerates other particles to extremely high velocities. Once those particles get a tremendous amount of energy together and then accelerator smashes them together, so there's a lot of energy in very tiny amount of space that creates more massive particles. Physicists look for traces of these particles in data collected by the detectors. The challenge is that these particles are also produced in many other processes, plus the Higgs boson only appears in about one in a billion LHC collisions. But careful statistical analysis of enormous amounts of data uncovered the particle's faint signal in 2012. Ten years ago, on 4 July 2012, the ATLAS and CMS collaborations presented compelling evidence for the discovery of a new particle, Higgs boson to a packed auditorium at CERN. This confirmed the existence of the Brout-Englert-Higgs mechanism, first predicted by theorists in the 1960s. In CERN’s auditorium, Peter Higgs wiped away tears of joy, and François Englert paid tribute to his late colleague and collaborator, Robert Brout, who did not live to see proof of the mechanism that bears his name. At Large Hadron Collider (LHC) experiment to produce Higgs bosons, two beams of particles are accelerated to very high energies and allowed to collide within a particle detector. The two experiments ATLAS and CMS at CERN, both of these are very big and really look like an alien spaceship. They're given lots of energy when smashed into each other. So as we know Einstein's equation (E=Mc2) that tells us that energy and matter are essentially interchangeable. The amount of mass you can make is equal to the energy (E) divided by square of the speed of light (c). So that tells you how heavy the particle is that you can possibly create. And that's one way of doing physics, that's how the Higgs was discovered. This particle had no electrical charge, it was short-lived and it decayed in ways that the Higgs boson should, according to theory. To confirm if it really was the Higgs boson, physicists needed to check its “spin” – the Higgs boson is the only particle to have a spin of zero as hypothesized in 1964 by Peter Higgs. In the mainstream media, the Higgs boson has often been called the "God particle" from the 1993 book The God Particle by Nobel Laureate Leon Lederman, although the nickname is not endorsed by many physicists. Discovering the Higgs boson was just the beginning. In the ten years since, physicists have examined how strongly it interacts with other particles, to see if this matches theoretical predictions. When two protons collide within the LHC, it is their constituent quarks and gluons that interact with one another. These high-energy interactions can, through well-predicted quantum effects, produce a Higgs boson, which would immediately transform – or “decay” – into lighter particles that ATLAS and CMS detectors could observe. The scientists therefore needed to build up enough evidence to suggest that particles that could have appeared from a Higgs production and transformation were indeed the result of such a process. Interaction strength can be measured experimentally by looking at Higgs boson production and decay: the heavier a particle the more likely the Higgs boson is to decay into or be produced from it. Interaction with tau leptons was discovered in 2016 and interaction with top and bottom quarks in 2018. But there is much more still to learn about this elusive particle.

 

 

The discovery of the Higgs boson was a historic event, but we are still only at the beginning in our understanding of this new particle. And to make some new, much heavier particle and you observe it like the Higgs; the mass of the thing that you can make is limited by how much energy you can put into the collision. Scientists are not done, Large Hadron Collider was not built just to find the Higgs boson it was built to find new particles, LHC was shut down for maintenance purpose just before the start of Run 3, they tightened the screws once again as they are going to lift it up to a much higher energy. The four big LHC experiments have performed major upgrades to their data readout and selection systems, with new detector systems and computing infrastructure. In 2022 CERN reopened the Large Hadron Collider after a three-year closure to upgrade the power; at these levels it might be able to find dark matter. The changes will allow them to collect significantly larger data samples, with data of higher quality than in previous runs. The LHCb experiment underwent a complete revamp and looks to increase its data taking rate by a factor of ten, while ALICE is aiming at a staggering fifty-fold increase in the number of recorded collisions. Run 3, a new period of data taking, began in July 2022 for the experiments at the Large Hadron Collider (LHC), after more than three years of upgrade and maintenance work; with collisions at unprecedented energy levels at the Large Hadron Collider (LHC) marking the launch of the new physics season at CERN’s flagship accelerator. The LHC will now run for close to four years at the record collision energy of 13.6 trillion electronvolts (TeV) – 6.8 TeV per beam. LHC Run 3 was started on 5 July, the day after the 10th anniversary of the discovery of the Higgs boson. The ATLAS and CMS detectors expect to record more collisions during Run 3 than in the two previous runs combined. To celebrate ten years of Higgs research at the LHC with CERN, the start of Run 3 of the LHC was streamed live on CERN’s social media channels and high quality Eurovision satellite link on 5 July 2022. CERN invited scientifically oriented people who are hungry for physics, to be present physically at CERN or online from around the world to enjoy the celebrations of the anniversary of this historical discovery, to celebrate past and present achievements for particle physics and science, to witness the start of Run 3 at the LHC on 5 July and to understand how CERN is preparing future research. Live commentary in five languages (English, French, German, Italian and Spanish) from the CERN Control Centre walked audience through the operation stages that take proton beams from their injection into the LHC to collision points. A live Q&A session with experts from the accelerators and experiments concluded the live stream. In preparation for data taking, the four big LHC experiments performed major upgrades to their data readout and selection systems, with new detector systems and computing infrastructure. The changes will allow them to collect significantly larger data samples, of higher quality than previous runs. The restart marked the beginning of preparations for the third run of the LHC, called Run 3, which planed four years of physics-data taking at world-record collision energy of 13.6 trillion electronvolts (13.6 TeV). The discovery of the Higgs was such a big deal and now that we have found it, we can move beyond everyday physics, there are dark matter, dark energy and black holes out there in the universe. Particle Physicists are hopeful that the Higgs boson will not simply be the end of one story, but the beginning of the next era in fundamental physics. The subsequent 10 years prior to Run 3 have seen impressive advances in our understanding of the Higgs boson's properties, and how they determine the features of the universe. There is much more still to be learned and so now...

It’s not the thing that bothers what came first; chicken or eggs?

But the biggest curiosity quest is dark matter with the boson Higgs.

 

 

This is First Deep Field image from NASA’s James Webb Space Telescope. It is the deepest and sharpest infrared image of the distant universe to date, looking far back in time when the Universe was less than a billion years old. This Webb’s First Deep Field image is covering a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground and yet overflowing with detail as it reveals thousands of galaxies – including the faintest objects ever observed in the infrared – have appeared in Webb’s view for the first time in this tiny sliver of vast Universe. It shows galaxy cluster SMACS 0723 as it appeared 4.6 billion years ago, with many more galaxies in front of and behind the cluster. There are stars, the things with the kind of cross twinkie patterns. But everything else, pretty much, is a galaxy. These are extremely distant galaxies, sort of almost out to the edge of as far as we can see with telescopes. So, for example, in the center of the image, you can see there's a kind of cluster of galaxies, kind of blobs. Now, hopefully you should be able to also see that on this image, there is this smearing pattern. So there's kind of circular structures arranged around this central cluster of galaxies. Einstein's notebooks indicate that he had realized that if an observer was located at the correct distance, the deflected light rays from around the celestial object would converge to make a magnified image. This phenomenon is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein's general theory of relativity that light should be bent by gravity. Gravitational lensing basically acts like a lens and we end up getting this kind of smeared multiple image of the same galaxy across the whole sky, which you can see in this JWST’s first image so called Webb Deep Field. Now we can use that to measure how much dark matter there is in the galaxies. There are a number of different ways of working out how much dark matter is out there in the universe. So there is the lensing method which can be used across the whole sky essentially and map the distribution of dark matter by how light is being bent through space and comparing it with the bending expected from the visible matter. Because more the gravity means more mass there is, the more strongly lensed the light will be and more will be the pronounced lensing effect. So we can use this lensing to effectively work out how much mass there is in the center of this image. And then we compare that with the visible light that we can see with our telescopes. We can see there are lots of galaxies here; this is obviously a very large amount of mass. So if we overlay a map of where the matter appears to be in this image from lensing, sometimes we actually find a very large discrepancy between the amount of stuff that we can see with our telescopes and the amount of stuff that we know needs to be there to explain this lensing effect; in this way we have evidence of dark matter from lensing. We can also trace the dark matter by looking at the rotations of stars around galaxies. We can calculate to a fairly high degree of confidence how much dark matter is out there, even though we can't see it which Vera Rubin famously proved it. Vera Rubin in the 1970s was looking at Andromeda and the other neighboring galaxies; she measured the rotation speeds of the stars in those galaxies. The expectation was that these galaxies were like the solar system with most of the mass concentrated towards the center. So closer to the center of the galaxy you have lots of gravity and the stars should be orbiting very quickly in order to not fall into the center and just like the planets the speeds of stars in the spiral disk were expected to fall as gravity gets weaker towards the edge of the galaxy, but this was not what Rubin found. The rotation speed of stars did not diminish but remained roughly the same all the way to the edge of the galaxies. She uncovered the discrepancy between the predicted and observed angular motion of galaxies by studying galactic rotation curves. Identifying the galaxy rotation problem, her work provided the first evidence for the existence of something called dark matter. It is essentially some kind of invisible substance which we don't know much about but apparently makes up a very large fraction of the universe.

 

Multi-wavelength studies have led to the discovery of numerous new objects in space & have allowed us to "see" the Universe as never before. With advances in technology & the ability to place telescopes into space, we can now see the Universe in all of its light! All the wavelengths of the electromagnetic spectrum have something important to say. We can learn from each wavelength, by observing the Universe in a various wavelengths of light to understand the complete picture. As I said in one of my blog, “Science Philosophy Singularity” that your shadow is relative incomplete true based on direction of light on you and so to get the complete truth of you we need shadows in all direction. Here visible or infrared light is just like that relative incomplete true and we have to consider light from all range of electromagnetic spectrum to get complete absolute truth about universe. Many objects reveal different aspects of their composition and behavior at different wavelengths. Objects are completely invisible at one wavelength, yet are clearly visible at another. Multi-wavelength astronomy fetch us complete picture of the universe as observing it in different wavelengths from radio, microwave, infrared, optical, ultraviolet, x-ray to gamma rays. Since the Webb's successful launch last year, now we have multi-wavelength composite images from Webb and NASA’s great observatories at various wavelengths. Chandra is an incredible piece of equipment and it is part of a suite of other observatories so called NASA's great observatories which includes Hubble, Spitzer and the Compton gamma-ray observatory. And together what that means is along with all the other telescopes and observatories around the world; there is fantastic set of data available to look into and work with. The multi-wavelength universe is just a really important thing in astronomy to collect data for many different kinds of light. Webb Deep Field shows how galaxy cluster SMACS J0723, located ~4.2 billion light-years away, contains hundreds of galaxies. Galaxy clusters are filled with vast reservoirs of superheated gas seen only in X-ray light. In the same image later Chandra data (blue in color) revealed gas with temperatures of tens of millions of degrees, possessing a total mass about 100 trillion times that of the Sun. Invisible dark matter forms an even larger fraction of the cluster’s total mass.

 

 

Scientist believes that Standard Model is definitely on to something as you don't get this kind of result by accident. So it’s a really stunningly successful theory, but it is not without some problems. And these problems are actually what motivated, in part, the building of the Large Hadron Collider in the first place. The discovery of the Higgs which is really kind of closing the chapter of 20th century physics and the beginning of the next era in fundamental physics paving the way to new physics. What everyone now actually is after the answers to some big, unsolved questions that the Standard Model cannot address. The cosmic pie depicts that ordinary matter of which made all the galaxies, and stars, and planets in the universe; everything that Standard Model describes is just 5% of the total content of the universe. And more than five times of the known universe that we are made of; is the invisible dark matter stuff which is 27% of that cosmic pie. And then 68% is something even more mysterious called dark energy, repulsive force that appears to be causing the universe to expand at an ever-increasing rate. So we don't know the 95% of the universe, the lesson from this is essentially that the word “dark” in physics means we don't know what we're talking about and that scientists themselves get very suspicious because it. That's pretty big of what's out there, so that is definitely a bit of an omission in the Standard Model. We have constructed what seems to be this stunningly successful theory over a century with all these clever experiments backing it up. But then we realize that what we've been describing is actually only a tiny fraction of the total content of the universe as having a theory that works really well in the very narrow domain in which we've applied it, but tells us basically nothing about major content of the universe. The search for the ultimate laws of nature with particle physics is nowhere near done and scientists know that they have a long way to go, but as far as the fundamental physics underlying particle physics is done when they discovered Higgs boson, the final piece of the puzzle of the matter that humans are pondering upon for 2,500 years since Democritus. The discovery of Higgs boson moment on July 4th 2012 is quite historic and not going to be forgotten. Its discovery in 2012 was a landmark in the history of physics. It explained something fundamental: how elementary particles that have mass get their masses. But it also marked something no less fundamental: the beginning of an era of measuring in detail the particle’s properties and finding out what they might reveal about the nature of the Universe. The collider had remained shut for three years as scientists worked on upgrading the facility for higher proton collisions than in 2012 when the God Particle was discovered, the detectors, electronics, and computing have all gone through substantial upgrades. There are also theoretical hints that the new physics should be found at accessible energy scales. Much of the efforts to find this new physics are focused on new collider experiments. LHC Run 3 with the increased data samples and higher collision energy expanded further the already very diverse LHC physics programme and now scientists at the LHC experiments will be searching for candidates for dark matter and for other new physics phenomena, either through direct searches or – indirectly – through precise measurements of properties of known particles and these more powerful collisions will allow us to explore further the particle world, and we will certainly learn much more.