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Kris Sigurdson
Kris Sigurdson is a Canadian physicist and cosmologist. He is an associate professor in the University of British Columbia's department of physics and astronomy in Vancouver, British Columbia. He was previously a NASA Hubble Fellow and Member of the Institute for Advanced Study. He received a Ph.D. in physics from the California Institute of Technology. Sigurdson is known for his work on the effects of dark matter interactions on cosmological perturbations, new models of dark matter particle physics, and the potential for observing signatures of the multiverse with cosmology. His other work includes contributions in the physics of the early universe, cosmological perturbation theory, and cosmic 21-cm fluctuations. In 2010, he co-authored a paper proposing the theory of hylogenesis, a theory of the origin of matter that links the formation of dark matter to baryogenesis. The theory predicts that in the long term protons or neutron The neutron is a subatomic particle, symbol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadians
Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''Canadian''. Canada is a multilingual and Multiculturalism, multicultural society home to people of groups of many different ethnic, religious, and national origins, with the majority of the population made up of Old World Immigration to Canada, immigrants and their descendants. Following the initial period of New France, French and then the much larger British colonization of the Americas, British colonization, different waves (or peaks) of immigration and settlement of non-indigenous peoples took place over the course of nearly two centuries and continue today. Elements of Indigenous, French, British, and more recent immigrant customs, languages, and religions have combined to form the culture of Canada, and thus a Canadian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Universe
The chronology of the universe describes the history and future of the universe according to Big Bang cosmology. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, with an uncertainty of around 21 million years at the 68% confidence level. The Planck Collaboration in 2015 published the estimate of 13.799 ± 0.021 billion years ago (68% confidence interval). See PDF: page 32, Table 4, Age/Gyr, last column. Outline Chronology in five stages For the purposes of this summary, it is convenient to divide the chronology of the universe since it originated, into five parts. It is generally considered meaningless or unclear whether time existed before this chronology: The very early universe The first picosecond (10−12) of cosmic time. It includes the Planck epoch, during which currently established laws of physics may not apply; the emergence in stages of the four known fundamental interactions or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
California Institute Of Technology Alumni
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the most populated subnational entity in North America and the 34th most populous in the world. The Greater Los Angeles area and the San Francisco Bay Area are the nation's second and fifth most populous urban regions respectively, with the former having more than 18.7million residents and the latter having over 9.6million. Sacramento is the state's capital, while Los Angeles is the most populous city in the state and the second most populous city in the country. San Francisco is the second most densely populated major city in the country. Los Angeles County is the country's most populous, while San Bernardino County is the largest county by area in the country. California borders Oregon to the north, Nevada and Arizona to the east, the Me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Academic Staff Of The University Of British Columbia
An academy (Attic Greek: Ἀκαδήμεια; Koine Greek Ἀκαδημία) is an institution of secondary or tertiary higher learning (and generally also research or honorary membership). The name traces back to Plato's school of philosophy, founded approximately 385 BC at Akademia, a sanctuary of Athena, the goddess of wisdom and skill, north of Athens, Greece. Etymology The word comes from the ''Academy'' in ancient Greece, which derives from the Athenian hero, ''Akademos''. Outside the city walls of Athens, the gymnasium was made famous by Plato as a center of learning. The sacred space, dedicated to the goddess of wisdom, Athena, had formerly been an olive grove, hence the expression "the groves of Academe". In these gardens, the philosopher Plato conversed with followers. Plato developed his sessions into a method of teaching philosophy and in 387 BC, established what is known today as the Old Academy. By extension, ''academia'' has come to mean the accumulation, dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Physicists
The following is a partial list of notable theoretical physicists. Arranged by century of birth, then century of death, then year of birth, then year of death, then alphabetically by surname. For explanation of symbols, see Notes at end of this article. Ancient times * Thales (c. 624 – c. 546 BCE) * Pythagoras^* (c. 570 – c. 495 BCE) * Democritus° (c. 460 – c. 370 BCE) * Aristotle‡ (384–322 BCE) * Archimedesº* (c. 287 – c. 212 BCE) * Hypatia^ªº (c. 350–370; died 415 AD) Middle Ages * Al Farabi (c. 872 – c. 950) * Ibn al-Haytham (c. 965 – c. 1040) * Al Beruni (c. 973 – c. 1048) * Omar Khayyám (c. 1048 – c. 1131) * Nasir al-Din Tusi (1201–1274) * Jean Buridan (1301 – c. 1359/62) * Nicole Oresme (c. 1320 – 1325 –1382) * Sigismondo Polcastro (1384–1473) 15th–16th century * Nicolaus Copernicusº (1473–1543) 16th century and 16th–17th centuries * Gerolamo Cardano (1501–1576) * Tycho Brahe (1546–1601) * Giordano Bruno (1548– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadian Cosmologists
Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''Canadian''. Canada is a multilingual and multicultural society home to people of groups of many different ethnic, religious, and national origins, with the majority of the population made up of Old World immigrants and their descendants. Following the initial period of French and then the much larger British colonization, different waves (or peaks) of immigration and settlement of non-indigenous peoples took place over the course of nearly two centuries and continue today. Elements of Indigenous, French, British, and more recent immigrant customs, languages, and religions have combined to form the culture of Canada, and thus a Canadian identity. Canada has also been strongly influenced by its linguistic, geographic, and ec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
21st-century Canadian Physicists
The 1st century was the century spanning AD 1 (Roman numerals, I) through AD 100 (Roman numerals, C) according to the Julian calendar. It is often written as the or to distinguish it from the 1st century BC (or BCE) which preceded it. The 1st century is considered part of the Classical era, epoch, or History by period, historical period. The 1st century also saw the Christianity in the 1st century, appearance of Christianity. During this period, Europe, North Africa and the Near East fell under increasing domination by the Roman Empire, which continued expanding, most notably conquering Britain under the emperor Claudius (AD 43). The reforms introduced by Augustus during his long reign stabilized the empire after the turmoil of the previous century's civil wars. Later in the century the Julio-Claudian dynasty, which had been founded by Augustus, came to an end with the suicide of Nero in AD 68. There followed the famous Year of Four Emperors, a brief period of civil war and inst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics. Protons and neutrons are not elementary particles; each is composed of three quarks. The chemical properties of an atom are mostly determined by the configuration of electrons that orbit the atom's heavy nucleus. The electron configuration is determined by the charge of the nucleus, which is determined by the number of protons, or atomic number. The number of neutrons is the neutron number. Neutrons do not affect the electron configuration, but the sum of atomic and neutron numbers is the mass of the nucleus. Atoms of a chemical element t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ratio). Protons and neutrons, each with masses of approximately one atomic mass unit, are jointly referred to as "nucleons" (particles present in atomic nuclei). One or more protons are present in the nucleus of every atom. They provide the attractive electrostatic central force which binds the atomic electrons. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol ''Z''). Since each element has a unique number of protons, each element has its own unique atomic number, which determines the number of atomic electrons and consequently the chemical characteristics of the element. The word ''proton'' is Greek for "first", and this name was given to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baryogenesis
In physical cosmology, baryogenesis (also known as baryosynthesis) is the physical process that is hypothesized to have taken place during the early universe to produce baryonic asymmetry, i.e. the imbalance of matter (baryons) and antimatter (antibaryons) in the observed universe. One of the outstanding problems in modern physics is the predominance of matter over antimatter in the universe. The universe, as a whole, seems to have a nonzero positive baryon number density. Since it is assumed in cosmology that the particles we see were created using the same physics we measure today, it would normally be expected that the overall baryon number should be zero, as matter and antimatter should have been created in equal amounts. A number of theoretical mechanisms are proposed to account for this discrepancy, namely identifying conditions that favour symmetry breaking and the creation of normal matter (as opposed to antimatter). This imbalance has to be exceptionally small, on the ord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hylogenesis
Hylogenesis is a physical theory about the mechanism behind the origins of dark matter and antimatter. It was proposed in August 2010 in a paper by Hooman Davoudiasl, David E. Morrissey, Kris Sigurdson and Sean Tulin. The theory involves a fermion X, and its antiparticle , both of which may couple into quarks in the visible sector, and into hidden particles in a hidden sector, a sector which is not part of the Standard Model. The hidden states have masses near a GeV and very weak couplings to particles in the Standard Model. X and respectively decay into either baryonic matter or hidden baryonic matter, and into either antibaryonic matter or hidden antibaryonic matter, violating CP and quark baryon number. An excess of baryonic matter is created in the visible sector, and an excess of antimatter is created in the hidden sector. The hidden antimatter is explained as being stable dark matter. The X and particles have a conserved baryon number charge, so equal and opposite charges a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Line
The hydrogen line, 21 centimeter line, or H I line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation has a precise frequency of , which is equivalent to the vacuum wavelength of in free space. This frequency falls below the microwave region of the electromagnetic spectrum, which begins at 3.0 GHz (10 cm wavelength), and it is observed frequently in radio astronomy because those radio waves can penetrate the large clouds of interstellar cosmic dust that are opaque to visible light. This line is also the theoretical basis of the hydrogen maser. The microwaves of the hydrogen line come from the atomic transition of an electron between the two hyperfine levels of the hydrogen 1 s ground state that have an energy difference of []. It is called the ''spin-flip transition''. The frequency, , of the quantum, quanta that are emitted by this transition between tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
