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Phantom Time

In History by Brian Koberlein2 Comments

In my last post, I talked about how historians can help us understand aspects of astronomy, such as the rate at which Earth’s rotation is slowing. The same thing can happen in reverse, where astronomy can confirm aspects of history. Take, for example, the Early Middle Ages, and the theory of phantom time. Read More

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Wonderful Precision

In Astronomy by Brian Koberlein1 Comment

On August 21 of 2017 the shadow of the Moon will trace a path across the United States. It’s a total solar eclipse that many will have the opportunity to observe. But whether you will observe totality or not depends on where you are. Astronomers have been able to predict the path of solar eclipses for millennia, but this new video demonstrates just how precise our predictions have become. Read More

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The Pace Of Time

In History by Brian Koberlein2 Comments

A day on Earth is longer than it used to be. The increase is tiny. Over the span of a hundred years the Earth’s day will increase by only a few milliseconds. It’s only been in the past few decades that we’ve been able to measure Earth with enough precision to see this effect directly. Using atomic clocks and ultra-precise measurements of distant quasars, we can measure the length of a day to within nanoseconds. Our measurements are so precise that we can observe various fluctuations in the length of a day due to things like earthquakes. Those fluctuations make it a challenge to answer another question. How has Earth’s rotation changed over longer periods of time?  Read More

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Black Holes, Bright Lights

In Black Holes by Brian Koberlein0 Comments

Supernovae are the bright, but short lived explosions of a dying star. At their brightest they can outshine an entire galaxy. The brightest ones, known as superluminous supernovae, can be more than 10 times brighter than type Ia supernovae used to measure the distances of far galaxies. But there’s a limit to how bright a supernova can be, so when we observed a supernova last year that seemed to exceed that limit, it raised an interesting question. Is our model of superluminous supernovae wrong, or is something else going on? Read More

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A Light Change

In Cosmology by Brian Koberlein6 Comments

One of the big mysteries of modern cosmology is the fact that the Universe is so uniform on large scales. Observations tell us our Universe is topologically flat, and the cosmic microwave background we see in all directions has only the smallest temperature fluctuations. But if the cosmos began with a hot and dense big bang, then we wouldn’t expect such high uniformity. As the Universe expanded, distant parts of it would have moved out of reach from each other before there was time for their temperatures to even out. One would expect the cosmic background to have large hot and cold regions. The most common idea to explain this uniformity is early cosmic inflation. That is, soon after the big bang, the Universe expanded at an immense rate. The Universe we can currently observe originated from an extremely small region, and early inflation made everything even out. The inflation model has a lot going for it, but proving inflation is difficult, so some theorists have looked for alternative models that might be easier to prove. One recent idea looks at a speed of light that changes over time.Read More

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Doing The Wave

In Physics by Brian Koberlein1 Comment

There has been a lot of digital ink spilled over the recent paper on the reactionless thrust device known as the EMDrive. While it’s clear that a working EM Drive would violate well established scientific theories, what isn’t clear is how such a violation might be resolved. Some have argued that the thrust could be an effect of Unruh radiation, but the authors of the new paper argue instead for a variation on quantum theory known as the pilot wave model. Read More

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The Stars Uncounted

In Cosmology by Brian Koberlein2 Comments

As we’ve recently seen, the cosmos is much larger than we’ve thought, with more than 2 trillion galaxies in the observable universe. Actually observing many of the most distant and faint galaxies is a real challenge, but more of them are being detected thanks to a trick that relies on relativity. Read More

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Jury Of One’s Peers

In Physics by Brian Koberlein5 Comments

The reactionless thruster known as the EM Drive has stirred heated debate over the past few years. If successful it could provide a new and powerful method to take our spacecraft to the stars, but it has faced harsh criticism because the drive seems to violate the most fundamental laws of physics. One of the biggest criticisms has been that the work wasn’t submitted for peer review, and until that happens it shouldn’t be taken seriously. Well, this week that milestone was reached with a peer-reviewed paper. The EM Drive has officially passed peer review. Read More