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A scientific fact/tidbit you recently learned that you thought was interesting

About the usual argument that travel faster than light is impossible... not just "we haven't invented it yet but wait a minute we don't really know what can be invented if it hasn't been yet so that totally means we can just invent whatever we can imagine" impossible, but actually "the nature of the way the universe works makes it fundamentally out of the question because the universe won't allow it no matter what we invent" impossible...

I've been willing to accept the conclusion that it's impossible, but part of the argument for that has always seemed off to me: the bit about how inventing FTL travel would equal inventing a time machine. Well, now I know that at least one legitimate physicist sees the same hole in it that I've always thought was the case.

https://www.youtube.com/watch?v=9-jIplX6Wjw
 
Warp drive is theoretically possible, but we'd have to find a way to basically bend the laws of physics around the ship or thing doing it. So I don't accept that it's impossible at all, although perhaps highly unlikely, at least not before we blow ourselves up.
 
Mike! said:
So, given the options, we'll be watching a pair of adoptive parents raise their young,and a cowbird baby too.
Click to expand...

Fore a little while. The cowbird chick will probably eventually push the other chicks out of the nest - some of them at least.
 
Delvo said:
About the usual argument that travel faster than light is impossible... not just "we haven't invented it yet but wait a minute we don't really know what can be invented if it hasn't been yet so that totally means we can just invent whatever we can imagine" impossible, but actually "the nature of the way the universe works makes it fundamentally out of the question because the universe won't allow it no matter what we invent" impossible...

I've been willing to accept the conclusion that it's impossible, but part of the argument for that has always seemed off to me: the bit about how inventing FTL travel would equal inventing a time machine. Well, now I know that at least one legitimate physicist sees the same hole in it that I've always thought was the case.

https://www.youtube.com/watch?v=9-jIplX6Wjw
Click to expand...

It's physically impossible for two objects in our universe to be moving apart from each other faster than the speed of light in exactly the same way that it's physically impossible for two objects on the surface of the earth to be further apart than 20040 km - the former is just the 4 dimensional equivalent of the latter. That's why fictional ways to get around it need to involve higher dimensions or something similar - leaving the universe at one point and then returning to it at a different point - which we don't know for sure to be impossible.
 
bigred said:
Warp drive is theoretically possible, but we'd have to find a way to basically bend the laws of physics around the ship or thing doing it. So I don't accept that it's impossible at all, although perhaps highly unlikely, at least not before we blow ourselves up.
Click to expand...
It's called the Alcubierre Drive after the person who first discovered this solution to General Relativity. Essentially it requires you to create a "bubble" of spacetime around your craft. Then when you travel you're moving at non-relativistic speed across the bubble, but the bubble itself is moving faster than light, which it can do because the light speed limit only applies to matter and energy, and not to spacetime itself. It's complicated but you're basically compressing spacetime in front of you, and stretching it behind, so your bubble and therefore the ship that it contains is pushed through the background spacetime faster than light could move through it. Or something like that - I'm hardly an expert.

The problem is that generating this spacetime bubble requires the use of exotic matter with negative mass, and no-one is really sure what that even means, let alone whether we could find or manufacture some.
 
I inherited about 20 'silver' commemorative coins, QEII Silver Jubilee and so on. I checked Ebay and some of these things are up for sale for a £ or two, so clearly not real silver but cupro-nickel alloy. Millions of those were sold.

Turns out that there's a simple test to distinguish between the alloy and the sterling silver versions ... drop a spot of domestic bleach on them and, in a minute or so, the silver darkens while the alloy remains shiny.

Turns out that the three coins in little display cases were actually silver. Total weight 102 gms, so sale value as scrap is around £60.

Interesting :)
 
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Roger Ramjets said:
The real problem is people not just accepting that traveling faster than light is impossible and treating any proposed workarounds as the fantasies they are.
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Let me guess, your grandpa said the same thing about travelling to the moon.

It's fantasy with technology as we know it today. The history of technology is filled with examples of what was once considered impossible and folly to consider otherwise that became a reality.
 
As a statement of historical fact in a few specific cases, that is true.

As a line of reasoning pointing to the conclusion that anything we want to imagine must be possible because other things have turned out to be possible before, the word "nonsense" is inadequate to express how far from anything resembling making sense it is.
 
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