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Speed Bubbles and Accelerated Reference Frames


Gagylpus

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So, I had an interesting realization the other day. We know that the speed bubbles from bendalloy or cadmium allomancy attach themselves to reference frames, and speed things up or slow them down relative to that reference frame. We know that those reference frames can be ones that experience acceleration: case in point, whenever a bubble attaches itself to the reference frame of the ground, which is rotating about Scadrial's axis and orbiting the sun. And, from the perspective of general relativity, any frame in which there is a gravitational field is really no different from an accelerated frame.

We also know, from descriptions of the experiences of characters within speed bubbles, that nothing weird happens in regards to their experiences of gravity. They feel the same weight inside a bubble as they would outside a bubble. When you drop something inside of a speed bubble, it falls to the ground at the rate you would expect to see outside the bubble: it doesn't float in the air or suddenly crash to the ground. (You might call this an extended version of Einstein's equivalence principle: you can't tell whether you are inside a speed bubble by doing measurements on the weights of objects.) All this means that, in order for there to not be any weird effects on the weight of objects inside speed bubbles, is that speed bubbles have to treat inertial forces and gravitational forces the same way, just as we would expect from general relativity.

And that means that if Wayne managed to anchor a speed bubble inside a large spinning centrifuge, he could observe the centrifuge slowed down (relative to the rate of time flow within the bubble) while still experiencing the full centrifugal force. If he dropped something inside, it would "fall" towards the outside of the centrifuge, even though the apparent motion of the centrifuge is practically stopped.

Does anyone know of any WoBs dealing with speed bubbles in accelerated frames, or in free-fall? Someone needs to ask Brandon what would happen if Wayne burned bendalloy while on a merry-go-round, or while skydiving. :D

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I was going to write up a long paragraph but realized I needed to think about it more.

For the time being, I'm just going to say that I don't think he's going to undergo the same centripetal force while still anchored to the same relative point on the centrifuge while inside a speed bubble since his velocity and therefore inward acceleration would be a lot lower, too low to keep him moving along the same circular path. 

Also, keep in mind that a released object in a centrifuge would go sideways until it contacted the wheel, it wouldn't fall outwards since it's velocity is tangential to the circular path it's on. Correct thanks to Gagylpus

Edited by Spoolofwhool
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On 9/8/2018 at 9:22 AM, Spoolofwhool said:

Also, keep in mind that a released object in a centrifuge would go sideways until it contacted the wheel, it wouldn't fall outwards since it's velocity is tangential to the circular path it's on.

From the point of view of a reference frame moving and rotating with the centrifuge, an object released in the centrifuge falls outwards radially. Same way that from the point of view of a reference frame attached to the earth's surface, an object falls towards the earth, even though its motion in another frame is (for example) a small section of a complex orbit around the sun.

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Highly speculative, but unless this experiment was conducted in a vacuum or at low speeds I would sort of expect the flux of air through the bubble's boundary to cause it to pop. Bubble's have an enormous effect on the momentum of things passing through them and I would hypothesize that too much flow through would cause the bubble to rupture. I don't have references to back that up, it's just my personal understanding. I invite you to burst my bubble on the matter...:lol:

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I like it and Ive been mulling similar things recently. The key for this is, I think, going to be the perception of the Allomancer in question.  There is one WOB that he made Speed bubbles immobile for story/power-balance reasons, but that does really get into the details of canon function.  But we've seen that they operate reasonably relative to their casters' planetary reference frame.  I have to assume ti would work equally well in instances of space-flight or artificial, centrifugal gravity in a space station scenario, where the perception is an enclosed system and more or less standing in for planetary conditions like gravity (which are/can be a function of Spiritual Connection in the Cosmere, just to complicate things).

But what about on a boat?  What about a really BIG Boat with no windows and little-to-no perceptible swaying? What about on a Train with constant speed and no windows?  Does being able to see the outside motion make a difference? And most likely to happen what happens if a Pulser falls off something really tall and pops a bubble in pure fear reaction? How about a Slider?

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what would happen if a Steelrunner fell of a cliff and then started storing speed. Would they fall slower?

I don't think they would fall slower. My understanding is that storing speed stores your ability to move your own body i.e. how fast your arms and legs move, not how fast you body moves relative to the ground.

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1 hour ago, Thrand_Antharo said:

I don't think they would fall slower. My understanding is that storing speed stores your ability to move your own body i.e. how fast your arms and legs move, not how fast you body moves relative to the ground.

I actually disagree here. 

The way that Bleeder acts when tapping speed makes it appear to be more of a temporal effect. She climbs out of a window and passes Wax from a floor above without either shattering the window frame or flying out over his head. Her running doesn't churn up the earth. She runs down stairs at a rate that her forward momentum should exceed gravity... It appears to be a speed bubble that ends at her skin and is anchored to her as physics apply to her as if she's moving normally. 

That said, if storing works the same way, then a steelrunner storing should fall slower... And it will make no difference because physics will still apply to them as if they are moving in standard time. 

Edited by Calderis
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Storing time seems likely, but at the same time, Sazed doesn't appear to have some change in temporal perception when he stores steel. 

Quote

Clubs hobbled into the kitchen. He seemed a blur to Sazed. Even wearing his spectacles—to help compensate for the vision he was storing in a tinmind—it was difficult for him to see.

"That's it," Clubs said, his voice muffled—another tinmind was taking Sazed's hearing. "They're finally gone."

Sazed paused for a moment, trying to decipher the comment. His thoughts moved as if through a thick, turgid

soup, and it took him a moment to understand what Clubs had said.

- Well of Ascension, Chapter 50

 

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@Calderis @Spoolofwhool Have you guys seen the flash TV show that has been coming out recently? In it, The Flash does a bunch of running and running up buildings and jumping and such. But they never show him slowing down when he's in the air, or jumping, or falling. In that particular show they would probably explain it away with the Speed Force, if they ever bothered to try to explain it. 

What I'm trying to take away from this particular anecdote is that 'Increased Speed' can mean a lot of things. In most settings, I assume that it increases your velocity in every possible way, including falling, normal running, and even things like how quickly you can twitch your eyes. In the cosmere, we can try to explain this weirdness using Perception and Intent. Storing speed makes you slow, so tapping speed makes you fast. But what does fast really mean? I'd argue that fastness and slowness are a function of the individual doing the travelling - gravity wouldn't even play a part in this part of the magic.

On a less theoretical level, I imagine it like this: any time your velocity would change, it changes twice as much according to how much speed you're tapping or storing.

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@tmnsquirtle I honestly don't care which explanation it is as long as it's consistent. The "accelerated in all directions" including gravity and speed of perception effectively has no difference than a temporal effect, which is why I view it that way.

If it's simply speed/momentum, gravity shouldn't be effected. 

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3 hours ago, tmnsquirtle said:

@Calderis @Spoolofwhool Have you guys seen the flash TV show that has been coming out recently? In it, The Flash does a bunch of running and running up buildings and jumping and such. But they never show him slowing down when he's in the air, or jumping, or falling. In that particular show they would probably explain it away with the Speed Force, if they ever bothered to try to explain it. 

I usually suspend any sort of disbelief about the science presented in superheroes stories. In any case, I don't watch, but I've seen Flash run up and down walls in comic books and it doesn't make any more sense.

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