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A Light Change

In Cosmology by Brian Koberlein5 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 Koberlein3 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

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The Tyranny Of Words

In Life by Brian Koberlein7 Comments

I haven’t been writing as many posts of late. Part of this is due to the usual time constraints of work and family, and part of it is due to a new large project that’s been ramping up recently. But part of it is due to the limitations of my own writing. Read More

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The Born Identity

In Quantum Mechanics by Brian Koberlein0 Comments

Quantum theory is probabilistic by nature. Because of fuzzy effects of quantum indeterminacy, the equations of quantum mechanics can’t tell us exactly what an object is doing, but only what the likely outcome will be when we interact with it. This probability is determined by the Born rule (named after physicist Max Born). The rule has various forms, but in the most common approach it means that squaring the wavefunction of an object yields the probability of a particular outcome. The Born rule works extraordinarily well, making quantum theory the most accurate scientific theory we have, but it is also an assumption. It’s a postulate of quantum theory rather than being derived formally from the model. So what if it’s wrong. Read More

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Emergence Of Gravity

In Dark Matter by Brian Koberlein8 Comments

As dark matter continues to vex astronomers, new solutions to the dark matter question are proposed. Most focus on pinning down the form of dark matter, while others propose modifying gravity to account for the effect. But a third proposal is simply to remove gravity from the equation. What if the effects of gravity aren’t due to some fundamental force, but are rather an emergent effect due to other fundamental interactions? A new paper proposes just that, and if correct it could also explain the effects of dark matter.Read More

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Close Enough

In Black Holes by Brian Koberlein13 Comments

A black hole is an object that has gravitationally collapsed under its own weight. It could be formed from the the remains of a dead star, a dense central region of a galaxy, or perhaps even a small fluctuation in the early dense moments of the cosmos. Regardless of the cause, the trick is to compress a large enough mass into a small enough volume. In other words, if the density of matter is high enough, it will collapse into a black hole.Read More