Albert Einstein, with his theory of special relativity, established that the speed of light is the absolute speed limit of the universe. A rocket ship attempting to accelerate to the speed of light encounters some well known effects: time dilation, mass increase, and length contraction. The closer to the speed of light it gets, the … Continue reading Why you can’t use quantum entanglement for faster than light communication
Tag: Physics
Recommendation: What Is Real?
Last week I started listening to a Sean Carroll podcast episode, an interview of Adam Becker on his book, What Is Real?: The Unfinished Quest for the Meaning of Quantum Physics. Before even finishing the episode, I downloaded Becker's book and read it. Becker starts out in the early decades of the 20th century, when … Continue reading Recommendation: What Is Real?
Is cosmology in crisis?
In past posts, when I've written about the expansion of the universe, I've generally referred to the rate of that expansion, the Hubble constant, as being around 70 km/s/megaparsec, that is, for every megaparsec a galaxy is distant from us, it's moving away at 70 kilometers per second faster. So a galaxy 100 megapasecs away … Continue reading Is cosmology in crisis?
Is cosmic inflation settled science?
Ethan Siegel at Starts With a Bang has a post up arguing that the multiverse must exist. His reasoning has to do with cosmic inflation. Inflation is the theory that the universe expanded at an exponential rate in the first billionth of a trillionth of a trillionth of a second of the big bang timeline. … Continue reading Is cosmic inflation settled science?
What’s at the edge of the universe?
Gizmodo has an interesting article that someone asked my thoughts on. Part of their "Giz asks" series, it asks various physicists what's at the edge of the universe? The physicists polled include Sean Carroll, Jo Dunkley, Jessie Shelton, Michael Troxel, Abigail Vieregg, and Arthur B. Kosowsky. They all give similar answers, that space isn't known … Continue reading What’s at the edge of the universe?
Why faster than light travel is inevitably also time travel
I've always loved space opera, but when I was growing up, as I learned more about science, I discovered that a lot of the tropes in space opera are problematic. Space operas, to tell adventure stories among the stars, often have to make compromises. One of the earliest and most pervasive is FTL (faster than … Continue reading Why faster than light travel is inevitably also time travel
Dark energy and repulsive gravity
Over the weekend, Sean Carroll put up a blog post to address common misconceptions about cosmology. I understood most of his points, but was confused when I saw this one: Dark energy is not a new force; it’s a new substance. The force causing the universe to accelerate is gravity. Carroll was referring to the accelerating … Continue reading Dark energy and repulsive gravity
Sean Carroll on the Many Worlds Interpretation of quantum mechanics
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
Do all quantum trails inevitably lead to Everett?
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?
Consciousness is composed of non-consciousness
The components of a thing are not individually the thing. For example, the components of the chair I type most of my blog posts from are not the chair itself, but the wood of the frame, the springs for the back and bottom, some metal parts for the reclining mechanism, the fabric coverings, cushions, etc. … Continue reading Consciousness is composed of non-consciousness
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