When Einstein was traveling to lecture in Spain,
He questioned a conductor again and again:
“It may be a while,”
He asked with a smile,
“But when does Madrid reach this train?”
(via Futility Closet)
How fast are you moving right now?
Even when you’re standing still, you’re moving, because Earth is moving, and so is the solar system, and so is the Milky Way … right?
The real question is compared to what?
Get ready for your introduction to relativity. Galilean relativity, that is. Really makes me wonder what’s absolute.
One thing I don’t agree with in this video is that space is “nothing”. Maybe in an idea sense, and in any useful measurable sense, but even interstellar space has a few atoms per cubic meter. Couldn’t we just measure relative to one of those? Ok, I’ll shut up.
Also, I wish Sulu had said that to Kirk back then. Also also, this narrator sounds a LOT like CGP Grey.
(by Tucker Hiatt for TED-Ed)
What’s a day to a mayfly?
What’s a decade to a man?
What’s a millennium to the universe?
It’s time to put time in perspective with this awesome graphical journey from Wait But Why. <- Start there, and then we’ll continue our adventure.
Our brains have a hard time putting the immense scale of Time (as in “all of it”, which is why it’s capitalized) into perspective. We’re just not built for that kind of thing. While we’re at it, scales of size throw us for a loop too.
That scale of that time, be it seconds, years or atomic oscillations of cesium atoms, is just the construction of humans, signposts along the way so that we can mark how different now-now is from then.
But wait, is now inherently different from then? Yes. That’s where time comes from in the first place. Time only moves in one direction. There’s a reason that the universe can not be reversed, a rule that makes today different from yesterday.
The arrow of time points forward. As long as the universe is getting messier, time will continue to tick on. Entropy, man. All the things are in a more disordered place than they just were, just then.
Life itself depends on the fact that the universe is not in thermal equilibrium. There are simply many more ways that matter can be disordered than it can be organized neatly, and our biochemical reactions take advantage of that. Be thankful for entropy.
Like Brian Cox says, there are more sand dunes than sand castles. I mean, probability says sometimes you’ll get a sand castle spontaneously forming on the beach, but you’ll get a gazillion random piles of sand in the meantime. So entropy marches on, and the universe gets disordered, and new nows become different from just thens.
Then why isn’t our world just some strange exception among the mess?
If ordered piles of molecules named Joe are just some rare, low-probability fluctuation in a universe that would much rather be in all kinds of disordered non-Joe-ness, then why does so much of the universe seem to look organized? I mean, there’s you, and there’s the rest of Earth, and the rest of everything. Why isn’t this the only planet, star, galaxy, etc?
Well, maybe we’re only a chicken that’s come out of a larger egg. Maybe we’re not a closed system. Maybe, there’s more beyond this universe?
That’s Sean Carroll’s idea anyway. Well, it’s not just his, but here he is talking about it in rather entertaining form at TEDxCaltech:
If any of this time business turns out to be too stressful, there’s a way out. But there’s a catch, it involves moving close to the speed of light. And if you dilate yourself out of this time scale, you’ll leave all of us behind, and we don’t want to see you go. Unless you take us with you. It’s that pesky twin paradox:
Gotta stop now. I’m out of time.
See and hear old Al’s mind in a new and tiny way!
Don’t get it?
“So you see, when you give up on the idea of a one true “at rest”, then you have to give up on the idea of a one true time as well! And even that is not the end of it. If you lose your one true way to see time, then you also lose your one true way to see size and your one true way to see mass. You can’t talk of any of that, if you don’t also say what it is you call “at rest”. If you don’t, then Bert or Dana can pick an “at rest” that isn’t the same as what you used, and then what they will get for time and size and mass won’t be the same.
What a snag, eh?”
It work. s.
Symphony of Science - Secret of the Stars
Brand new release celebrating E=MC^2 from melodysheep featuring Michio Kaku, Brain Cox, Neil deGrasse Tyson, Brian Greene and Lisa Randall.
Truth is stranger than the strangest fiction.
Immovable Object vs. Unstoppable Force … Who Wins?
Well … the first one doesn’t really exist in the scope of relativity, and the second one would result in the end of the universe. Another fun physics thought experiment from MinutePhysics!
Or, put more simply, how the heck does Santa hit hundreds of millions of homes and cover 122 million miles in a single night?
Their explanation involves a subterranean community of Norwegian exiles that have been independently evolving at the North Pole for centuries, development of “relativity clouds” in which they can control time and space relative to the outside world, molecular morphing in order to sneak into children’s homes via the tiniest cracks, an immense antenna network to listen to children’s thoughts, and nano-toy-makers to manufacture gifts on the spot.
What takes the jolly old guy six months in “Santa time” appears to happen in a blink of an eye to us! Basically, he’s like Einstein in a red suit.
It could happen.
Remember in Super Mario Brothers, how the music and time would speed up when you started running low on the clock? Well, here’s a new level of video game time-freakiness, all about relativity.
Strange things happen to our perception of the universe when we travel close to the speed of light (you know, if we could travel close to the speed of light). Special relativity, as worked out by Einstein and others, gives us plenty of weirdness when it comes to our perception of time and distance at those extreme speeds. MIT’s Game Lab has developed a game that simulates that experience. It’s called A Slower Speed of Light.
The closer we get to the speed of light, time slows down for us relative to someone watching us (“time dilation”), light shifts to red and blue, and the lengths of things contract in the direction we are moving. Weirded out yet? Ethan Siegel has a pretty good explanation of all those strange effects.
In the game, the object is to collect these orbs. As you grab each one, the speed of light slows down a bit. That means that you get closer and closer to traveling at the speed of light, and the game shifts the visuals and your movement to give you an idea of what that might feel like. It is not unlike a relativistic drug trip.
The game is available for Mac and PC. Pause the Halo and give relativity a whirl. It’s a video game that Einstein would have approved of!
(via Discovery News)
As is noted in the letter above, this is a universe in which the laws of special relativity declare that an object moving near the speed of light will experience time dilation, the relative slowing of time, compared to an observer.
This is also a universe that can not fully explain its expansion or what happened at the very moment at which it was formed, and therefore must invoke the idea that there are many universes, each existing like a bubble in a sudsy bathtub.
But even if the second is true, that there are many universes, perhaps an infinite number, I’m glad I live in the one where Carl Sagan wrote Timothy Leary a letter about the first.
I'm Joe Hanson, a Ph.D. biologist and science writer based in Austin, TX. I'm the creator/host/writer of PBS Digital Studios' It's Okay To Be Smart. Subscribe on YouTube by clicking below:
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