Cosmologists and astronomers have found a discrepancy in the Hubble constant from opposite ends of the universe. Continue reading
Why did the Universe have such low entropy at the start? Are the laws of physics consistent across the multiverse? Can we see evidence of other regions of the multiverse? Sean Carroll discusses thermodynamics and the Universe. Continue reading
Can we see things travelling faster than light?
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Thanks to Prof. Geraint Lewis for input on earlier drafts of this video.
The expanding universe is a complicated place. During inflation the universe expanded faster than light, but that’s something that actually happens all the time, it’s happening right now. This doesn’t violate Einstein’s theory of relativity since nothing is moving through space faster than light, it’s just that space itself is expanding such that far away objects are receding rapidly from each other. Common sense would dictate that objects moving away from us faster than light should be invisible, but they aren’t. This is because light can travel from regions of space which are superluminal relative to us into regions that are subluminal. So our observable universe is bigger than our Hubble sphere – it’s limited by the particle horizon, the distance light could travel to us since the beginning of time as we know it.
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Could We Detect Parallel Universes?
Somewhere out there, there might be a different version of you—or maybe trillions of different yous. How could that be? String theory suggests that other universes exist alongside our own.
While it’s unclear if we might ever be able to lift the veil between realities, depending on what kind of amalgamation of universes we exist in, it might be possible for us to see evidence of parallel realities. World Science Festival co-founder and Columbia University physicist Brian Greene explains how in the video above.
By: World Science Festival Staff
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The big bang theory is the most accepted theory for the formation of the universe. The “big bang” is a misnomer because there was no explosion, but rather a rapid expansion. It is not known what existed the moment before the big bang, however the evolution of the universe from the first instant after the big bang and onwards is well understood. Continue reading