Intelligent aliens, if they exist in the galaxy or the Universe, might be detectable from a variety of signals: electromagnetic, from planet modification, or because they’re spacefaring. But we haven’t found any evidence for an inhabited alien planet so far....
Artist’s logarithmic scale conception of the observable universe. The Solar System gives way to the Milky Way, which gives way to nearby galaxies which then give way to the large-scale structure and the hot, dense plasma of the Big Bang...
If you look farther and farther away, you also look farther and farther into the past. If the number of galaxies, the densities and properties of those galaxies, and other cosmic properties like the temperature and expansion rate of the...
The expanding Universe, full of galaxies and the complex structure we observe today, arose from a smaller, hotter, denser, more uniform state. Although the extent of the observable Universe, today, takes us out some 46 billion light-years in all directions,...
By firing a pulse of light at a semi-transparent/semi-reflective thin medium, researchers can measure the time it must take for these photons to tunnel through the barrier to the other side. Although the step of tunneling itself may be instantaneous,...
The ‘raisin bread’ model of the expanding Universe, where relative distances increase as the space (dough) expands. The farther away any two raisins are from one another, the greater the observed redshift will be by the time the light is...
This 1847 painting, known as Galileo before the Holy Office, depicts Galileo during his trial for blasphemy by the Catholic Church. Although we normally equate relativity with Einstein, it was Galileo who first, and correctly, formulated a theory of relativity...
This view of the Hercules galaxy cluster showcases an enormous number of large, massive galaxies clustered together in a single region of space. Although these galaxies contain most of the stars within this region of space, there are several dozen...
Particle accelerators can either be linear, where magnets collimate beams of particles while electric fields accelerate them, or circular, where bending electromagnets recirculate particles as electric fields kick them to higher and higher energies with each pass. Although all particle...
This 1934 photograph shows Einstein in front of a blackboard, deriving special relativity for a group of students and onlookers. Although special relativity is now taken for granted, it was revolutionary when Einstein first put it forth, and doesn’t even...
