Interstellar travel is the hypothetical travel of spacecraft from one star system, solitary star, or planetary system to another. Interstellar travel is expected to prove much more difficult than interplanetary spaceflight due to the vast difference in the scale of the involved distances. Whereas the distance between any two planets in the Solar System is less than 55 astronomical units (AU), stars are typically separated by hundreds of thousands of AU, causing these distances to typically be expressed instead in light-years. Because of the vastness of these distances, non-generational interstellar travel based on known physics would need to occur at a high percentage of the speed of light; even so, travel times would be long, at least decades and perhaps millennia or longer.
Keynesian economics are the various macroeconomic theories and models of how aggregate demand strongly influences economic output and inflation. In the Keynesian view, aggregate demand does not necessarily equal the productive capacity of the economy. It is influenced by a host of factors that sometimes behave erratically and impact production, employment, and inflation.
In physics, the twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, as a consequence of an incorrect and naive application of time dilation and the principle of relativity, each should paradoxically find the other to have aged less. However, this scenario can be resolved within the standard framework of special relativity: the travelling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey. Another way of looking at it is to realize the travelling twin is undergoing acceleration, which makes them a non-inertial observer. In both views there is no symmetry between the spacetime paths of the twins. Therefore, the twin paradox is not actually a paradox in the sense of a logical contradiction. There is still debate as to the resolution of the twin paradox.
The Bussard ramjet is a theoretical method of spacecraft propulsion for interstellar travel. A fast moving spacecraft scoops up hydrogen from the interstellar medium using an enormous funnel-shaped magnetic field ; the hydrogen is compressed until thermonuclear fusion occurs, which provides thrust to counter the drag created by the funnel and energy to power the magnetic field. The Bussard ramjet can thus be seen as a ramjet variant of a fusion rocket.
A starship, starcraft, or interstellar spacecraft is a theoretical spacecraft designed for traveling between planetary systems. The term is mostly found in science fiction. Reference to a "star-ship" appears as early as 1882 in Oahspe: A New Bible.
An interest rate is the amount of interest due per period, as a proportion of the amount lent, deposited, or borrowed. The total interest on an amount lent or borrowed depends on the principal sum, the interest rate, the compounding frequency, and the length of time over which it is lent, deposited, or borrowed.
Paul Robin Krugman is an American economist who is the Distinguished Professor of Economics at the Graduate Center of the City University of New York and a columnist for The New York Times. In 2008, Krugman was the sole winner of the Nobel Memorial Prize in Economic Sciences for his contributions to new trade theory and new economic geography. The Prize Committee cited Krugman's work explaining the patterns of international trade and the geographic distribution of economic activity, by examining the effects of economies of scale and of consumer preferences for diverse goods and services.
The General Theory of Employment, Interest and Money is a book by English economist John Maynard Keynes published in February 1936. It caused a profound shift in economic thought, giving macroeconomics a central place in economic theory and contributing much of its terminology – the "Keynesian Revolution". It had equally powerful consequences in economic policy, being interpreted as providing theoretical support for government spending in general, and for budgetary deficits, monetary intervention and counter-cyclical policies in particular. It is pervaded with an air of mistrust for the rationality of free-market decision making.
In classical economics, Say's law, or the law of markets, is the claim that the production of a product creates demand for another product by providing something of value which can be exchanged for that other product. So, production is the source of demand. In his principal work, A Treatise on Political Economy, Jean-Baptiste Say wrote: "A product is no sooner created, than it, from that instant, affords a market for other products to the full extent of its own value." And also, "As each of us can only purchase the productions of others with his/her own productions – as the value we can buy is equal to the value we can produce, the more men can produce, the more they will purchase."
Zero interest-rate policy (ZIRP) is a macroeconomic concept describing conditions with a very low nominal interest rate, such as those in contemporary Japan and in the United States from December 2008 through December 2015 and again from March 2020 until March 2022 amid the COVID-19 pandemic. ZIRP is considered to be an unconventional monetary policy instrument and can be associated with slow economic growth, deflation and deleverage.
In finance, an exotic option is an option which has features making it more complex than commonly traded vanilla options. Like the more general exotic derivatives they may have several triggers relating to determination of payoff. An exotic option may also include a non-standard underlying instrument, developed for a particular client or for a particular market. Exotic options are more complex than options that trade on an exchange, and are generally traded over the counter.
Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society to design a plausible uncrewed interstellar probe. Intended mainly as a scientific probe, the design criteria specified that the spacecraft had to use existing or near-future technology and had to be able to reach its destination within a human lifetime. Alan Bond led a team of scientists and engineers who proposed using a fusion rocket to reach Barnard's Star 5.9 light years away. The trip was estimated to take 50 years, but the design was required to be flexible enough that it could be sent to any other target star.
A liquidity trap is a situation, described in Keynesian economics, in which, "after the rate of interest has fallen to a certain level, liquidity preference may become virtually absolute in the sense that almost everyone prefers holding cash rather than holding a debt which yields so low a rate of interest."
Intergalactic travel is the hypothetical crewed or uncrewed travel between galaxies. Due to the enormous distances between the Milky Way and even its closest neighbors—tens of thousands to millions of light-years—any such venture would be far more technologically and financially demanding than even interstellar travel. Intergalactic distances are roughly a hundred-thousandfold greater than their interstellar counterparts.
Tyler Cowen is an American economist, columnist and blogger. He is a professor at George Mason University, where he holds the Holbert L. Harris chair in the economics department. He hosts the economics blog Marginal Revolution, together with co-author Alex Tabarrok. Cowen and Tabarrok also maintain the website Marginal Revolution University, a venture in online education.
Economic stagnation is a prolonged period of slow economic growth, usually accompanied by high unemployment. Under some definitions, slow means significantly slower than potential growth as estimated by macroeconomists, even though the growth rate may be nominally higher than in other countries not experiencing economic stagnation.
The neoclassical synthesis (NCS), neoclassical–Keynesian synthesis, or just neo-Keynesianism was a neoclassical economics academic movement and paradigm in economics that worked towards reconciling the macroeconomic thought of John Maynard Keynes in his book The General Theory of Employment, Interest and Money (1936). It was formulated most notably by John Hicks (1937), Franco Modigliani (1944), and Paul Samuelson (1948), who dominated economics in the post-war period and formed the mainstream of macroeconomic thought in the 1950s, 60s, and 70s.
Space trade is interplanetary or interstellar trade. Plans and ideas on how trade functions have been published by Futurists and pundits since the 1960s, though science fiction writers have been envisioning such trade for several more decades.
The Great Stagnation: How America Ate All the Low-Hanging Fruit of Modern History, Got Sick, and Will (Eventually) Feel Better is a pamphlet by Tyler Cowen published in 2011. It argues that the American economy has reached a historical technological plateau and the factors that drove economic growth for most of America's history are no longer present. These figurative "low-hanging fruit" include the cultivation of much free, previously unused land, technological breakthroughs in transport, refrigeration, electricity, mass communications, sanitation, and the growth of education. Cowen, a professor of economics at George Mason University, theorizes that these factors have contributed to stagnation in the median American wage since 1973.
Leslie Robert Shepherd was a Welsh nuclear physicist. He was involved in the design and operation of the experimental Dragon reactor, which used helium as a coolant. He was also an advocate of space exploration, serving as the president of the British Interplanetary Society and the International Astronautical Federation.
