In a somewhat whimsical podcast episode, Sean Carroll explores the physics and "rules" of time travel. Probably the first two thirds explore the physics. Carroll notes that if time travel under general relativity is at all possible, it would more likely involve a spaceship attempting to navigate some kind of closed timelike curve than stepping … Continue reading The rules of time travel?
Quantum physics has been on my mind again lately, somewhat triggered by a recent conversation with Wyrd Smythe on his blog. I've always known quantum nonlocality has nuances, but stuff I read this week revealed some wrinkles I wasn't aware of. (Well, I was aware of them, but wasn't aware they pertained to nonlocality.) A … Continue reading The nature of quantum nonlocality
The main difference between a quantum computer and a classical one is the qubit. Qubits are like classical bits, in that they hold binary values of either 1 or 0, on or off, true or false, etc. However, qubits, being quantum objects, can be in a superposition of both states at once. The physical manifestation … Continue reading Thoughts about quantum computing and the wave function
I just finished reading Jim Baggott's new book Quantum Reality: The Quest for the Real Meaning of Quantum Mechanics - a Game of Theories. I was attracted to it due to this part of the description: Although the theory quite obviously works, it leaves us chasing ghosts and phantoms; particles that are waves and waves … Continue reading Quantum Reality
With quantum physics, we have a situation where a quantum object, such as a photon, electron, atom or similar scale entity, acts like a wave, spreading out in a superposition, until we look at it (by measuring it in some manner), then it behaves like a particle. This is known as the measurement problem. Now, … Continue reading The measurement problem, Copenhagen, pilot-wave, and many worlds
Related to the post last week on quantum mechanics, here is a talk that got mentioned in the discussion thread. Warning: Carroll is a passionate advocate for the Many Worlds Interpretation, so don't expect a fair and balanced discussion. The video is about an hour long. http://www.youtube.com/watch?v=iXRLDatmbgA A couple of points. Carroll notes that we … Continue reading Sean Carroll on the Many Worlds Interpretation of quantum mechanics
I've been thinking lately about quantum physics, a topic that seems to attract all sorts of crazy speculation and intense controversy, which seems inevitable. Quantum mechanics challenges our deepest held most cherished beliefs about how reality works. If you study the quantum world and you don't come away deeply unsettled, then you simply haven't properly … Continue reading Do all quantum trails inevitably lead to Everett?
There's a new interpretation of quantum mechanics: Scientists propose existence and interaction of parallel worlds: Many Interacting Worlds theory challenges foundations of quantum science -- ScienceDaily. This new interpretation appears to be similar to the MWI (Many Worlds Interpretation) where quantum superpositions don't collapse, but spread, creating what amounts to new universes. However, in this theory, … Continue reading New interpretation of quantum physics: Many Interacting Worlds
Sean Carroll has posted a passionate defense of the Many-world interpretation to quantum mechanics. I have often talked about the Many-Worlds or Everett approach to quantum mechanics — here’s an explanatory video, an excerpt from From Eternity to Here, and slides from a talk. But I don’t think I’ve ever explained as persuasively as possible why I think it’s the right approach. So that’s what … Continue reading Sean Carroll makes the case for the Many-worlds interpretation of quantum mechanics
"Anyone who is not shocked by quantum theory has not understood it." --Niels Bohr "If you think you understand quantum mechanics, you don't understand quantum mechanics." --Richard Feynman Quantum mechanics are utterly bizarre. Quantum particles behave like spread out waves, until their position is measured, when they suddenly behave like a particle with definite position. The … Continue reading A debate on quantum mechanics interpretations