People
Around 340 B.C., this Greek philosopher suggested the Earth was a sphere based on observations of moon eclipses.
Who is Aristotle?
Relativity required abandoning the idea of this type of time, on which all good clocks agree.
What is absolute time.
We can describe the position of a point in space using three of these.
What are coordinates?
Max Planck suggested that light and other electromagnetic waves could be given off only in these certain discrete packets.
What are photons?
His geocentric model of the universe, featuring the Earth at the center surrounded by celestial spheres, was later adopted by the Christian church
Who is Ptolemy?
According to general relativity, time runs differently for observers at different heights in this field
What is a gravitational field?
The theory of relativity forced a fundamental change in our ideas of space and time, combining them to form this four-dimensional object.
What is space-time?
This concept states that there is no distinction between waves and particles, and particles may sometimes behave like waves
What is wave/particle duality?
This Polish astronomer proposed the idea of a stationary sun with the Earth and planets orbiting it, a revolutionary departure from earlier models.
Who is Copernicus?
This common scenario involving two subjects, where one ages less due to traveling at near light speed
What is the twins paradox?
The surface of the earth is given as an example of this kind of space, which is finite but has no boundary
What is curved space?
This principle states that nature imposes limits on our ability to predict the future because you cannot accurately measure both a particle's position and velocity simultaneously
What is the uncertainty principle?
Publicly supporting Copernicus, this German astronomer discovered that planetary orbits are elliptical, not perfectly circular, as part of a Sun-centered system.
Who is Kepler?
According to Einstein's Special Theory of Relativity, time is not absolute but runs differently for observers depending on this
What is their relative motion?
Modern models are based on two simple assumptions about the universe: that it looks identical in whichever direction we look, and that it would look this way if we were observing from anywhere else
What are homogeneity and isotropy?
According to quantum theory, even "empty" space is filled with pairs of these that only exist temporally in quantum interactions
What are virtual particles?
This Danish astronomer was the first to calculate that light travels at a finite speed by observing the eclipses of Jupiter's moons in 1676.
Who is Roemer?
The theory of relativity implies you can travel backward in time if you can travel this fast.
What is faster than light?
String theories seem to be consistent only if space-time has either ten or twenty-six of these, instead of the usual four.
What are dimensions?
This theory, a leading candidate for a quantum theory of gravity, proposes that the fundamental objects in the universe are not point particles but have length with different elementary particles corresponding to different vibration patterns of these objects
What is string theory?