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general relativity

  • Gubser_HERO-2

    A Letter to Einstein from the Future

    Two Princeton physicists catch Albert up.

  • super-kamiokande_HERO

    7 Major Experiments That Still Haven’t Found What They’re Looking For

    Being an experimental scientist can sometimes seem like a thankless task. You may be used to reading headlines about experiments that end up making great discoveries, but less is heard about the (often heroic) efforts of experimentalists that have yet to detect or observe what they set out to. Some of these efforts have spanned […]

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    The Tangled History of Big Bang Science

    Diagram outlining the critical stages of evolution of the Universe from the Big Bang to the present.CERN / Flickr For a theory of the universe as successful as the Big Bang, it may come as a surprise to realize how many complications its promoters had to stumble through. Let’s begin with the unfortunate figure of […]

  • orbital rotation_HERO

    Why Rotation Makes No Sense Sometimes

    What is orbital rotation? The basic picture is clear enough: One body is at rest, while the other follows some circular or elliptical path around it. The trouble is just to figure out which body is which. If you’re standing on the surface of the earth, it appears that the sun slowly orbits around you […]

  • Gerace_HERO

    My Personal Hero: Alan Lightman on William Gerace

    Several years ago, I attended a Buddhist retreat in which I was introduced to the idea of the “retinue,” a constellation of influential and supportive people whom one imagines in an enveloping cloud as one meditates. Mentors. I took the concept one step further and decided to create an actual photo montage that I could […]

  • White Holes

    “White Holes” Could Exist—But That Doesn’t Mean They Do

      A black hole is a one-way door to oblivion. According to general relativity, once anything crosses its boundary—the event horizon—it cannot return to the outside. For that particle, the black hole is the entire future. We’ll never actually get a chance to see the particle live out that destiny: Any light the particle emits […]

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    The Most Massive Object in the Universe—How Was It Created?

      The galaxy known prosaically as M87 doesn’t look like much. Unlike beautiful spiral galaxies (including the Milky Way), M87 appears as an orangish blob of stars through telescopes. Its only noticeable feature is the long streamer of gas emanating from the galactic center. The source of that jet is far from prosaic, however: It’s […]