What do we mean by “the Universe”? In the physics community, we would define “the Universe” as all “observable things”, ranging from the entire cosmos to stars and planets, and to small elementary particles that are invisible to the naked eye. Observable things would also include recently made discoveries that we are slowly coming to understand more, such as the Higgs boson, gravitational waves, and black holes.
Spiral galaxies like the Milky Way and its neighbour, the Andromeda Galaxy, contain about 100 billion stars each, the light of which can be seen by eye. Also visible are small amounts of dust, typically enshrouding the sites of young star formations.
The current era in the Western hemisphere is marked by growing public distrust of “intellectual elites.” The present U.S. administration openly disregards, or even suppresses, relevant scientific input to policy formulation.
It’s nearly 60 years since C.P. Snow gave his influential “Two Cultures” lecture, in which – among many other significant insights – he advocated that a good education should equip a young person with as deep a knowledge of the Second Law of Thermodynamics as of Shakespeare. A noble objective, but why did Snow highlight this particular scientific law?
Rarely has a research field in physics gotten such sustained worldwide press coverage as gravity has received recently. A breathtaking sequence of events has kept gravity in the spotlight for months: the first detection(s) of gravitational waves from black-holes; the amazing success of LISA Pathfinder, ESA’s precursor mission to the LISA gravitational wave detector in space; the observation — first by gravitational waves with LIGO and Virgo, and then by all possible telescopes on Earth and in space — of the merger of two neutron stars, an astrophysical event that likely constitutes the cosmic factory of many of the chemical elements we find around us.
The centre of the Milky Way is a very crowded region, hosting a dense and compact cluster of stars—the so-called nuclear star cluster—and a supermassive black hole (SMBH) weighing more than 4 million solar masses. A star cluster is an ensemble of stars kept together by their own force of gravity. These large systems are found in the outskirts of every type of galaxy, being comprised of up to several million stars.
As a mathematician who focuses his attention on a field called dynamics, I am often asked when queried about my area of specialty, exactly what is a dynamical system? I usually answer something like: “I study the mathematics underlying what is means to model something mathematically.” And this seems to work as most people have a basic understanding that mathematics is used in science and engineering to model either a physical or an abstract process and to mine it for information.
Healthcare is expensive, and not just in high income countries. Those who are suffering or struck by illness in resource limited countries are often unable to afford services that can provide them the care they need. Inequitable access to health services continues to be among the greatest public health challenges of our time. Since becoming […]
The periodic table turns 150 next year. Given that all scientific concepts are eventually refuted, the durability of the periodic table would suggest an almost transcendent quality that deserves greater scrutiny, especially as the United Nations has nominated 2019 as the year of the Periodic Table. These days it seems that physics gives a fundamental explanation of the periodic table, although historically speaking it was the periodic table that gave rise to parts of atomic physics and quantum theory. I am thinking of Bohr’s 1913 model of the hydrogen atom and his extension of these ideas to the entire periodic table.
A February 2017 Workshop on Robustness, Reliability, and Reproducibility in Scientific Research was sponsored by the US National Science Foundation (NSF). The workshop was part of NSF’s response to growing concerns in Congress triggered by increasing media coverage of an apparent lack of reproducibility among findings, especially in clinical sciences. The participants, spanning diverse scientific subfields, were charged to assess the extent of any problems of reliability and reproducibility, and to formulate next steps toward solutions.
In 2004, John Prescott, then Deputy Prime Minister in Tony Blair’s New Labour government, remarked, “the tectonic plates appear to be moving”, referring to the impending downfall of Mr Blair. Since then, the tectonic plates metaphor has been applied to just about every major political transition, including events following the UK referendum on leaving the European Union and the election of Donald Trump as US President.
At the center of every galaxy is a supermassive black hole. Looking at the wider scale, is it possible that these gravity monsters influence the overall structure of our universe? Using a new computer model, astrophysicists have recently calculated the ways in which black holes influence the distribution of dark matter, how heavy elements are produced and distributed throughout the cosmos, and where cosmic magnetic fields originate.
Frank Wilczek famously wrote: “A recurring theme in natural philosophy is the tension between the God’s-eye view of reality comprehended as a whole and the ant’s-eye view of human consciousness, which senses a succession of events in time. Since the days of Isaac Newton, the ant’s-eye view has dominated fundamental physics. We divide our description of the world into dynamical laws that, paradoxically, exist outside of time according to some, and initial conditions on which those laws act.
Ever since it was realised that the stars are other suns, people have wondered whether any of them are accompanied by planets, or ‘exoplanets’ as we now call them. Speculation along these lines were among the charges that led to Giordano Bruno being burned at the stake in the year 1600. It is only since the 1930s that astronomers seriously thought they had the observational tools to be able to find out.
At the beginning of the 19th century, Thomas Young proved that light was a wave phenomenon. He did so by illuminating a screen (in an otherwise darkened room) with a beam of sunlight that had passed through a card with two slits in it. The proof was the interference pattern on the screen, whose alternating light and dark portions could only have occurred if light consisted of waves, not particles.
White dwarfs are the remnants of solar-like stars that have exhausted the reservoir of fuel for the nuclear fusion reactions that powers them. It is widely believed, based on theoretical considerations, that young white dwarfs should experience a phase of contraction during the first million years after their formation. This is related to the gradual cooling of their interior which is not yet fully degenerate.