Cosmere Physics "lite" AMA

[DrPhysics he/him]

I've introduced myself in other places, but I'm a physics professor who is also a big fan of Sanderson's works. There are a lot of in-depth physics discussions on various topics all over this forum. This isn't that.

I wanted to start a thread for those who have simple questions about Cosmere (or other Sanderson works) physics, but without diving off the deep end. 
So, if you have a question but don't want to debate the proper way to model a steelpush (or if those threads just feel way too intimidating), ask it here and I'll do my best to answer.

If we run into a topic that could use a more in-depth discussion, we can spin it off into a new thread and I'll edit this original post to include a brief summary and a link.

[+asmodeus]

How do you think allomantic speed and slow bubbles work? Considering they're ignoring red-shift and such.

[DrPhysics he/him]

4 hours ago, asmodeus said:

How do you think allomantic speed and slow bubbles work? Considering they're ignoring red-shift and such.

The short answer: magic makes time go faster/slower (and yes, I know that answer is facetious). 

They break so many physical laws, that I can't make any good predictions or explain them any other way. Beyond redshift, you'd also have to worry about things like super fast air molecules crossing the boundary and heating the rest of the room (Wayne would just cook everthing). They also increase (or reduce for slow bubbles) the pull of gravity. The way gravitational forces work, if someone dropped something in a bubble, someone outside the bubble should meaure it falling at the same rate we'd expect in the regular room, and anyone in the bubble would see it fall much too slowly (and they'd be apparently much lighter), and we dont see that happening.

 

We do have ways to slow down/speed up time, but there is no way to create something like a speed bubble using those principles (bending spacetime to that degree would shred everything that passes through the edge of the bubble and the energy released would kill everyone in the room, even after compensating for redshift).

 

Therefore, since there is no real world physics that can even approximate speed bubbles, we're stuck with "magic makes time go faster/slower".

[SteelBagel]

conservation of momentum with iron feruchemcy? whats up with that? Also, does it store weight, mass, gravity, or what's the deal exactly?

[DrPhysics he/him]

5 hours ago, SteelBagel said:

conservation of momentum with iron feruchemcy? whats up with that? Also, does it store weight, mass, gravity, or what's the deal exactly?

It stores mass (otherwise you wouldn't change speed mid-air).

The short version of momentum is that without outside forces, the value of mass times velocity doesn't change. So, if you decrease your mass (without pushing on the mass that you are losing), you will speed up.

If iron feruchemy changed how hard gravity was pulling on you, instead of speeding up in mid-air, you'd keep going at the same speed, but you wouldn't fall as quickly.

 

There are a few people who argue about whether or not iron feruchemy conserves momentum if you change reference frames (e.g. Wax is in the train, what does someone outside the train see), but all of those problems go away if you imagine that the mass that you store (or tap) changes its speed so that it is at rest with respect to whatever the allomancer considers at rest (e.g. in the train example, any stored (or tapped) mass is moving at the speed of the train).

[Duxredux he/him]

In Bands of Mourning at one point when Wax and Wayne are fighting the small army at the end of the book, Wax charges an Allomantic grenade with Steel, and gets it to Wayne. Wayne whoops and throws the little cube at the Set soldiers and it knocks their weapons out of their hands. Is this an inconsistency with how Steelpush physics and Ettmetal have been portrayed, or is this indicating something about the "relative mass" that a Godmetal has when Pushing? Normally I would expect the little cube to get deflected, not continue in an arc and continuing to Push on the weapons. Presumably the primer cube is not modulating its Push like a Coinshot or Mistborn might subconsciously. What's going on here?

[DrPhysics he/him]

17 minutes ago, Duxredux said:

Is this an inconsistency with how Steelpush physics and Ettmetal have been portrayed, or is this indicating something about the "relative mass" that a Godmetal has when Pushing? Normally I would expect the little cube to get deflected, not continue in an arc and continuing to Push on the weapons. Presumably the primer cube is not modulating its Push like a Coinshot or Mistborn might subconsciously. What's going on here?

It is unusual, but not the only place where this oddity pops up. Sometimes the push/push back follows Newton's third law, (I push on something, it pushes back just as hard), and sometimes it doesn't.  Another similar scene happens in Hero of Ages where Elend and a steel inquisitor both push on the same object and the inquisitor moves much more than Elend, (the inquisitor thought that they'd both be thrown back the same amount, like what would happen with Newton's third). 

The book purposely makes a point of highlighting the oddity, so my best guess is there is some sort of "push mass" that depends on the allomancer's strength or perception of their strength that makes them respond less strongly to pushes than they should. The same effect must be what is going on with the grenade.

[idanstark42 he/him]

On 11/10/2023 at 6:01 AM, DrPhysics said:

How do you think allomantic speed and slow bubbles work?

There's a WoB about it being based off of gravitational time dialation, so I would say it has something with locally changing the metric. This is still, as @DrPhysics said, problematic with a lot of physical principles.

WoB:
https://wob.coppermind.net/events/199/#e7747

[Dofurion]

@DrPhysics, could you summarize what we understand by Adhesion and Abrasion in real life?

I recently saw a theory in which they would be opposites in the Voidchart and shortly after a video appeared on Youtube where they explained their interaction in conditions of 0 gravity and how Adhesion allows normal ballpoint pens to function in space and allows the capillarity of plants in the Earth.

Edited August 19, 2024 by Dofurion

[DrPhysics he/him]

On 8/14/2024 at 5:39 AM, idanstark42 said:

There's a WoB about it being based off of gravitational time dialation

I'm hoping that's changed (14 year old quote). Bubble behavior has about as much in common with gravitational time dilation as a car does with a speedboat (they have engines and move things). The only similarity is that they can both make time go slow. 

[Treamayne]

On 8/14/2024 at 7:39 AM, idanstark42 said:

There's a WoB about it being based off of gravitational time dialation, so I would say it has something with locally changing the metric. This is still, as @DrPhysics said, problematic with a lot of physical principles.

WoB:
https://wob.coppermind.net/events/199/#e7747

42 minutes ago, DrPhysics said:

I'm hoping that's changed (14 year old quote). Bubble behavior has about as much in common with gravitational time dilation as a car does with a speedboat (they have engines and move things). The only similarity is that they can both make time go slow. 

Definitely an old WoB - and Brandon does not say Speed Bubbles are gravitational Time Dilation, he said he treated it similarly (but had not yet solved the RedShift/BlueShift problem at the time of the WoB). Slightly updated WoB:

Spoiler

<edited for length and relevance>

Do you ever run into problems with that, does it break physics?

Brandon Sanderson

Oh, yeah. If you look too deep in a fantasy book we are breaking the laws of thermodynamics and we are breaking causality. Those are the two big ones. And those are very important things to be… very dangerous things to be breaking. And you could probably write a fantasy novel that didn’t break those two things. Maybe? I don’t know. The way I avoid breaking laws of thermodynamics is by saying, we’ve got investiture that things can transfer into as well. We’ve got matter, energy, and investiture, I’ve added something to the tripod and therefore it looks like I’m just bending the laws of thermodynamics.

When you actually get down into the nitty-gritty, it starts to break down. It just has to. Causality is the big one. Once you have people teleporting and things like this, run the train experiment. I mean, you just have to say “It’s magic” at some point in a fantasy book. For most of them. I think you could do it, but in mine, with a  grand scale magic system I want to do, we just have to say, “at that point it’s magic.” And this is how I think a fantasy writer differs from a science fiction writer.

A SF writer takes today and extrapolates forward. I take what is interesting and extrapolate backward. Usually. For instance speed bubbles. “I want to have speed bubbles. This is how they work. Peter, tell me the physics.” And we work it out together. We work out physics and try to hit the big trouble points and build into the magic why certain things happen. But that doesn’t stop us from making speed bubbles where there is time passing differently without using mass or whatnot to create time dilation, and it causes all kinds of weird things to happen.

Boskone 54 (Feb. 19, 2017)

Note he specifically says it is not using Mass as a cause or contributing factor in the Dilation. More specifically, he has since indicated that because Cosmere Physcis has the third tine (not just matter and energy, but Matter, Energy and Investiture) that the boundry of a Speed Bubble is converting energy to/from investiture (in the Spiritual Realm) to compensate for Red and Blue Shift. So, excess energy as an object passes is converted to Investiture and moves to the Spiritial Realm and when additional energy is required it pulls investiture from the Spiritual Realm, converting it to energy as it enters the physical realm. It's the same type of Required Secondary Power as what allows an Atium Burner to understand the extra information gained from Shadows, or a Skimmer to survive their own compressed tapped weight.  WoBs:

Spoiler

Quote

Steeldancer (paraphrased)

 According to General Relativity, there should be spatial distortion in speed bubbles. So, why does no one notice it?

Brandon Sanderson (paraphrased)

There is spatial distortion in speed bubbles, that's why bullets are refracted when they enter a bubble. However, I played with it a bit, and ignore the redshift that should happen. The barrier of the bubble absorbs it, otherwise everyone would just be irradiated. 

FanX Spring 2019 (April 19, 2019)

Quote

Questioner

Speed bubbles--

Brandon Sanderson

Yes. Ehhhh... these are the hardest ones.

Questioner

We've seen them work and move with trains, we've seen them not work with carriages: is there a size requirement, or is it how they view themselves?

Brandon Sanderson

That's a good question. So I build in this thing, right? I'm like "Oooh, speed bubbles! Speed bubbles are cool!" but the Delorean problem, right? You're like "I'm going to go back in time: to the middle of SPACE", because the planet is in the same position, right? This is stuff that science fiction writers have been having fun with since the silver age of science fiction. So I'm like "Alright, I need to deal with the Delorean problem". And so I'm like "Alright, we're going to have to say that frame of reference is a big part of it: so perception and frame of reference is a big part of it; and also size of the thing that you're on". So it would be possible to use kind of cosmere cognitive training to get that speed bubble moving with you-- And someone asked me a question about this on tour, I believe, so it would be in one of the reports-- Not this exact same thing, but "Could they learn to move their speed bubble with them?" And yes you can.

Questioner

So it is how the allomancer views it, not how the thing views itself?

Brandon Sanderson

That's a part of it. Partially how it view itself, *garbled* It's really also mass. Big thing-- The speed bubbles required all kinds of physics-gymnastics. I'm sorry physicists, but once you start playing with time the stuff you gotta do. It's just crazy stuff you gotta do.

Questioner

We actually sat down and worked out what the metric would have to do to have a speed bubble-- Yeah, it was gnarly.

Brandon Sanderson

...We did run the math on these things, and stuff like that. And Peter, y'know, he rais-- "Redshift" and stuff like this we talked about. And all kinds of fun stuff about speed bubbles that I then had to--

Bystander

Khriss asked about that?

Brandon Sanderson

Yeah. So this is-- This one and manipulating weight... Those are the math ones. So these are the ones where-- They create the fun things to talk about, but they are where this is fantasy and not science fiction. Like a lot of these questions I could answer and you'd be like "Alright, if there were this alternate power source, we could buy this" but in this case we're like exception-list-of-asterisks to make it work. But they're too fun to not do, right? And I knew I was doing gravity on Stormlight, so I'm like "I gotta do weight separately".

Arcanum Unbounded Chicago signing (Dec. 6, 2016)

 

 

Edited August 21, 2024 by Treamayne
SPAG

[DrPhysics he/him]

On 8/19/2024 at 3:34 PM, Dofurion said:

could you summarize what we understand by Adhesion and Abrasion in real life?

It's tough to draw too much inference from real-world physics on these ones.

Abrasion is essentially power over friction. Specifically, being able to get rid of friction. To take it to the absolute most basic level, when two objects rub against each other, there is a force (friction) parallel to that surface that opposes the direction of the slip. The force is due to two main components: 1: rough surfaces will have little parts that interlock and bounce and jostle against each other; 2: some surfaces will actually form weak electromagnetic bonds when brought into contact. (Note: since electromagnetic bonds are what make things solid, the rough parts bouncing and jostling against each other are also the result of electromagnetic forces).

Full lashings (the physical part of adhesion), make things stick. It appears to act similar to static electricity, but much stronger. So, once again, it would be the result of manipulating electromagnetic forces.

At first glance, it might look like adhesion and abrasion are opposites, with one increasing the force and the other decreasing, but that breaks down when you dig deeper. For example, adhesion is an attractive force, perpendicular to a surface (it pulls things together). Its opposite would need to be a repulsive force, also perpendicular to the surface. 

The opposite of abrasion would be a force that greatly increases friction, preventing slipping. But such a force wouldn't make it harder to pick up an object, just harder to slide it.

Both work by manipulating electromagnetic forces, but so do tension and cohesion.

Therefore, real-world physics doesn't give us any hints on how the two compare. We can only rely on what we observe in the books, and that is summarized pretty well in this article on the coppermind.

[Heilven he/him]

On 11/8/2023 at 11:43 AM, DrPhysics said:

but don't want to debate the proper way to model a steelpush

See that's really funny because I just spent a bunch of time yesterday developing a mathematical model for steelpushes/ironpulls instead of studying for the GRE.

On 11/14/2023 at 5:15 PM, DrPhysics said:

Sometimes the push/push back follows Newton's third law, (I push on something, it pushes back just as hard), and sometimes it doesn't.  Another similar scene happens in Hero of Ages where Elend and a steel inquisitor both push on the same object and the inquisitor moves much more than Elend, (the inquisitor thought that they'd both be thrown back the same amount, like what would happen with Newton's third). 

I really hate that you reminded me of that though, I was only remembering Vin pushing Kredik Shaw to pieces and was willing to chalk that up to weird shardicness. Here I was happy about coming up with an explanation for why pushing a coin doesn't send you flying until the coin hits the ground. I'll probably still make a thread showcasing some of the math and my findings, but I figure I have to agree that some sort of "push mass" sounds reasonable to explain the behavior without throwing out conservation of momentum

[DrPhysics he/him]

6 hours ago, Heilven said:

Here I was happy about coming up with an explanation for why pushing a coin doesn't send you flying until the coin hits the ground.

You might want to take a look at this thread where we discuss it in depth.

https://www.17thshard.com/forums/topic/158274-steelpush-physics/

 

That said, it would be fun to see your model.

Edited August 22, 2024 by DrPhysics

[AffordableInvestiture He/Him]

Would radiants using the surge of gravitation to lash themselves multiple times cause them to experience g-forces? I suppose stormlight would help them withstand the effects.

[alder24]

27 minutes ago, AffordableInvestiture said:

Would radiants using the surge of gravitation to lash themselves multiple times cause them to experience g-forces? I suppose stormlight would help them withstand the effects.

They should not, but they do experience G forces. And yes, Stormlight makes it manageable. WoR ch 52:

Quote

Fearless, he fell. This was his ocean to swim, his winds upon which to soar. He fell face-first toward the next plateau. Just before he arrived, he Lashed himself sideways and backward.
His stomach lurched. He felt like someone had tied a rope around him and pushed him off a cliff, then yanked on the rope right as he reached the end of it. The Stormlight inside, however, made the discomfort negligible. He pulled sideways, into another chasm.

 

Spoiler

shinarit?

There is that scene where Kaladin takes a sharp turn at high speeds and he almost blacks out. That is normal for jet pilots, since they experience high G forces when their airplane tries to accelerate them by their backs and bottoms.

But Lashing doesn't work that way, it generates fake gravity. Accelerating your whole body shouldn't cause you anything, you can't even feel it.

Is this something that is an admitted physics hiccup or I misunderstood this kind of Investiture usage?

Brandon Sanderson

This one is actually in the process of flux, as I do more research on the effects of acceleration (including interviews with fighter pilots, which has been fun.) Basically, I realized I needed to beef up my understanding of all this, and then make some decisions on exactly how this all works, because I've been relying on instinct too much in some of these sequences.

So...that's a RAFO, I'm afraid. More because I'm still tweaking some of the little details of how I want this all to work. (In ways that become increasingly relevant as I look forward toward things like Windrunners in space.)

There are a ton of details to consider, even if I eventually hand-wave some of it with the magic. (For example, the heart pumping blood in a high-g environment. How does that interact, if at all, with stormlight? And the direct oxygenation of the brain implied by not needing to breathe while holding stormlight...)

We have several very large math-ish projects going on behind the scenes.

Phoenixdown

I think it depends on if lashing independently impacts each atom within your body simultaneously, or if it is only a subset.

Brandon Sanderson

There's one important fact you're not considering, but which is vital: reader expectation.

One of the questions I have to ask myself is this: What will the reader expect to happen? How will they expect to feel? Granted, none of us have ever flown like this before--but we generally imagine similar things, similar feelings.

As a writer, one thing I need to balance is when I go against reader expectations and when I don't. Going against the expectations can be interesting, but often takes a large burden of words and explanation to keep reminding them something is not how they'd imagine it to be.

For example, it took a relatively large amount of reader attention (and explanation) to keep reminding people in Mistborn that plants weren't green and the sky wasn't blue. In many ways, making something new (like a chull) is easier on readers than making something familiar into something strange (like the horses in Dragonsteel, which were smaller than Earth horses--and kept causing confusion problems in my alpha readers.)

As annoying as this example can me, this is why Lucas had sound, fire, gravity, etc in space. Starships banking in formation felt real to the viewers, even if it didn't make sense in context. I hope to not go that far, but these questions are something in my mind.

I try to be careful not to remove the sensations of magic, in order to keep the movements of characters grounded. Windrunning has left me having to decide how far I want to go with things like this, in order to preserve the visceral feelings for the reader.

General Reddit 2018 (June 6, 2018)

 

Edited August 23, 2024 by alder24

[idanstark42 he/him]

On 8/22/2024 at 6:08 PM, Heilven said:

See that's really funny because I just spent a bunch of time yesterday developing a mathematical model for steelpushes/ironpulls instead of studying for the GRE.

I really hate that you reminded me of that though, I was only remembering Vin pushing Kredik Shaw to pieces and was willing to chalk that up to weird shardicness. Here I was happy about coming up with an explanation for why pushing a coin doesn't send you flying until the coin hits the ground. I'll probably still make a thread showcasing some of the math and my findings, but I figure I have to agree that some sort of "push mass" sounds reasonable to explain the behavior without throwing out conservation of momentum

Have you posted this anywhere? I loved the steelpush physics thread the @DrPhysics referenced, I'm sure I'd love to see your model.

[DrPhysics he/him]

On 8/23/2024 at 3:27 PM, AffordableInvestiture said:

Would radiants using the surge of gravitation to lash themselves multiple times cause them to experience g-forces? I suppose stormlight would help them withstand the effects.

@alder24 did an excellent job explaining what we see in the books. I just noticed that he didn't address why we wouldn't expect them to feel g-force (or when physics predicts that they would).

 

Short answer: You can't feel gravitational forces directly. That's why astronauts are weightless in space even though gravity is holding them in orbit.

 

Longer answer: What do you mean we can't feel gravity directly? I feel it every time that I stand up.

There are three big pieces to this:

1. Every single piece of the earth pulls on every single tiny piece of you.
2. Gravitational forces only change strength on planetary scales (e.g. the Sun's gravitational field at Earth's orbit is much stronger than its field at Jupiter's orbit), so the amount that Earth pulls on a little piece of your toe is equal to the amount that it pulls on a little piece of your head.
3. Since the force is so uniform, our body has no sensors that can pick it up. When you feel your weight while standing you aren't feeling gravity, you feel how much tension you need to keep in each muscle in order to not fall down.

The same thing actually happens with pressure forces as well. Pressure increases as you go deeper into the water because each layer of water has to hold up all the layers of water above it. One way to test this it to take a water bottle, poke a hole in the side, and watch the water stream out. The water at the bottom of the bottle feels both atmospheric pressure (pushing on the top of the water) and the pressure due to the water above it. When you poke this hole, the higher-pressure water is exposed to atmospheric pressure and the water flows from high pressure (inside the water bottle) to low (outside).

Before all the water runs out, drop the bottle. You'll see that the water stops leaking out while it is falling. Since everything is falling together, the water at the bottom doesn't have to hold up the water above it anymore, everything stays at atmospheric pressure and without a pressure difference, the flow stops.

The negative impacts of g-forces (at least the blackout ones) on humans are primarily due to the pressure difference between our feet and our heads. In normal conditions, our hearts pump hard enough to overcome that difference and force our blood to go through our body. 

Now imagine we're in a cockpit turning up. To do that, the seat pushes hard on us to go up, but it only pushes on our surface. So, the part of me next to the seat has to push up the part just above it, and that has to push up on the part above it, etc. creating a big pressure difference. When that pressure difference gets big enough, our heart can't pump hard enough to raise the blood from our feet to our head, our brain loses oxygen, and we pass out. We can actually take much stronger g-forces going forward than we can going up because the distance from the back of our head to the front is much smaller than the distance from our feet to our head, which makes the pressure difference smaller for the same g-force because the stuff at the back of our head doesn't have to hold up as much weight. (People have maintained consciousness pulling 45 g's in the "eyeballs in" direction).

So back to lashings. If lashings simply redirected gravity, we'd be free falling and wouldn't get a pressure difference across our body, because each part is being pulled on equally, therefore, no g-forces. 

But, you would start to feel g-forces as wind resistance picks up. Falling at terminal velocity feels similar to lying on the floor. You can actually feel the weight of your body. So, if you did a double lashing, at first you wouldn't feel anything, but as you sped up, eventually you'd reach a point where you felt twice as heavy just because of the wind pushing you. Changing the lashings would let you change directions very quickly without feeling g-forces, but you'd hit limits on actual windspeed and could black out. Over long distances, you'd max out at around 1.5 lashings (face first), because that's the max a person can feel for an extended time (more than a couple of seconds). We put astronauts in a position that maximizes the amount of g's they can handle for a long time, and we still limit our rockets to 2 g's to keep our astronauts safe (which is why we can't use a rocket designed for satellites to carry people.)

[Duxredux he/him]

Hm. A question then for @DrPhysics, if I understand the previous posts and scenario of Kaladin experiencing g-forces, g-forces are experienced when there is a pressure differential in the body.

Based on the WoB posted by @alder24, the questioner thinks that we may see this effect because Lashings are not affecting the whole object simultaneously. Could we explain what we see in the books based on instinctual reflex and if Lashings take time to spread through the object? I know for Steelpushing physics, quite a lot of what we see that seems odd can be explained by subconscious reflex, like Kelsier and Vin's Pushing match working if they are aiming above center, and I was wondering if we could use similar conjecture for Lashing.

My first assumption is that humans can withstand compression far better than shearing or tension. Lezian's final defeat by Kaladin seems like a decent example of what can go wrong if Lashings are not applied fully or simultaneously across the body, though those were not basic Lashings. My assumption is that the Windrunner would instinctively Lash from the side opposite the new direction of motion, so if Lashing forward, the back would get Lashed first. This should make the forces experienced compression, rather tension. This isn't too different from pushing off with the back foot when beginning to walk or using the lead leg to slow down when stopping, as opposed to stopping by going into the splits by dragging the rear leg.

I might also expect Lashings to spread externally to internally, since again, our body is accustomed to our legs propelling our body and our ribcage moving internal organs rather than our body being dragged along by our internal organs.

Would this be a decent explanation for what Kaladin experiences, and mechanically how to Lash things with minimal damage anyway? It seems like a natural result as well for Lashing other objects, since most of the time someone would reach out and Lash something away from them, rather than directly toward them, and requiring the power to move from the outside in also makes sense.

The complications of Lashings transferring throughout an object seem more interesting as well. What if a dozen Windrunner tried to Lash a spaceship but were unsynchronized? What if a Windrunner or a Skybreaker tried to create opposing gravitational forces on opposite side of an opponent?

[DrPhysics he/him]

On 10/19/2024 at 6:45 AM, Duxredux said:

My assumption is that the Windrunner would instinctively Lash from the side opposite the new direction of motion, so if Lashing forward, the back would get Lashed first. This should make the forces experienced compression, rather tension. This isn't too different from pushing off with the back foot when beginning to walk or using the lead leg to slow down when stopping, as opposed to stopping by going into the splits by dragging the rear leg.

Where this breaks down is all the times they describe reorienting so that the ceiling is "down". If it started on one side and worked its way over, that would feel like getting pushed toward the wall/ceiling, not falling towards it. And if you made the lashing travel fast enough for those scenes to work, it would be too fast to get the scenes right when a windrunner is "flying".

 

There isn't a physical answer that can get both of those situations to agree. It will have to be a cognitive or spiritual explanation that works in-universe. Right now, the only explanation I can think of is the Doylist: "Brandon thinks flight should be like a fighter jet, but gets gravity right in all the other places" or "most of my audience expects flight to be like jets, so I need to treat it that way, so they aren't taken out of the story." Since there are no jets on Roshar, we can't really use the excuse that lashing work weird during flight because Kaladin believes they should work like a jet.

 

It definitely makes it difficult to predict anything about what spaceflight will look like on Roshar.

 

Some of the odd physics mistakes (usually violating Newton's first law) that pop up with steel pushes are easier to explain because most people don't understand the first law, and so those behaviors are expected. (Like Vin slowing down and stopping when she pushes herself straight up. Her momentum should keep her going, so she'd overshoot, then fall, and keep bouncing up and down. However, we're used to straining upwards and stopping when we do things like standing up on our toes.)

Edited October 20, 2024 by DrPhysics
Spelling/clarity

[Dofurion]

@DrPhysics I have an idea about physics and I want to know if it is feasible or not.

You see, I'm just an amateur when it comes to physics, but I'm very interested in the curiosities that one can find. I recently found a meme on Pinterest that talked about non-Euclidean space, specifically this one:

So I started looking for information about non-Euclidean space and found that it is basically what allowed Einstein to develop his theory, by considering the deformations of space and that it did not always "go straight." Then the typical visual representation of the tarp and the balls came to my mind.

A 2D representation to understand approximately what it would look like in 3D.

Then I realized something, normally these materials go back to being completely flat when you remove the objects inside of it. But that's because of the material these demonstrations are normally made with, if they were made with something like plastic this would leave a mark on it. So let's say that mark is elliptical, the sum of its internal angles should be greater than 180°, if you force something like that to become "straight" again you would end up with something longer than you had in the beginning. This is normally due to the thinning of the materials but what if with space it simply resulted in the creation of more space?

Summing up, could dark energy be an emergent quality of the creation of space that is forced to resume Euclidean characteristics after the objects that deformed it left that specific point?

Again, I'm not an expert on the subject, I don't know if I'm missing something that contradicts everything I wrote or if there is already a similar conjecture. Also, what I write is not fully understood when translated. I just wanted to see if someone could help me out with this doubt and frankly you are the only physicist I know.

I also know that this question has nothing to do with the Cosmere but I don't think it's wrong to ask it in this thread.

[Sythrin]

On 11/8/2023 at 6:43 PM, DrPhysics said:

 

I've introduced myself in other places, but I'm a physics professor who is also a big fan of Sanderson's works. There are a lot of in-depth physics discussions on various topics all over this forum. This isn't that.

I wanted to start a thread for those who have simple questions about Cosmere (or other Sanderson works) physics, but without diving off the deep end. 
So, if you have a question but don't want to debate the proper way to model a steelpush (or if those threads just feel way too intimidating), ask it here and I'll do my best to answer.

If we run into a topic that could use a more in-depth discussion, we can spin it off into a new thread and I'll edit this original post to include a brief summary and a link.

 

Could you use speedbubbles to manipulate pressure?

Like during the space age, when a ship is breached or has leak. Could they create a speedbubble in that place, to temporarily contaminate the hole? 

@DrPhysics

And my second question is a bit abstract but I hope I can explain it well enough.

One surge that always interested me is  of transformarion.

And I ask myself. Is there a substance/ a matter that we in our modern times cannot (or with very great hardship) create because of lack of technology or energy, but we know exist (at least theoreticly).

And could we create this much easier with Soulcasting? Do you know any? Like Helium-3? And what kind of ramifications would that be?

Edited November 28, 2024 by Sythrin

[DrPhysics he/him]

16 hours ago, Dofurion said:

Summing up, could dark energy be an emergent quality of the creation of space that is forced to resume Euclidean characteristics after the objects that deformed it left that specific point?

No. Those dents would leave gravitational anomalies that we'd be able to see through the gravitational impacts. Dark energy is trying to describe a different effect: something is taking the sheet and pulling,stretching it out, and that pulling is speeding up. We can describe that stretching with general relativity if we assume there is some other energy that we can't see (hence the "dark") filling the entire universe helping push.

[DrPhysics he/him]

On 11/28/2024 at 4:43 AM, Sythrin said:

Could you use speedbubbles to manipulate pressure?

I actually answered that one in another, longer post.
 

 

On 11/28/2024 at 4:43 AM, Sythrin said:

And could we create this much easier with Soulcasting? Do you know any? Like Helium-3? And what kind of ramifications would that be?

Helium 3 would be useful for power generation, but since you could generate electricity with a simple heat fabrial connected to a Sterling engine, there really wouldn't be a need.

 

Where it could be useful would be materials science and/or the semiconductor industry. There are specific alloys and crystal structures that simulations tell us would be more useful that what we have,  but the technology to build and test them is very cost prohibitive. So, if a souldcaster could grow something by imagining the exact crystal structure (potentially including gemstones) that could be very useful. (Think commercially available spider silk for bridge construction, or a steel that lets us run plane engines a few degrees hotter, increasing their efficiency).

 

The only other one would be nuclear materials for weapons, but it would be very difficult to soulcast those without killing the soul caster. (You don't want to just stand next to a big chunk of plutonium). Could make for some very scary suicide bombers.

Edit to add: after posting, I realized that with how easy anti-light is to make, we wouldn't need kissable materials for a big bomb. Just two gems and a bit of raysium. 

Easy bomb: a tube weighted at one end (so that end stays down) with a stormlight filled gem at the bottom, and a little piece of Raysium on top of it. Second gem at the top of the tube held up by something designed to break away. Drop the tube, on impact the top gem will fall and hit the Raysium, connecting the two gems and mixing the lights. Once the gems are destroyed in the initial explosion, the light and anti-light are released mixing completely. Goodbye target. 

 

You wouldn't need ICBMs, just a windrunner with a backpack.

Edited November 29, 2024 by DrPhysics
Had a new idea.

[Corgen]

4 hours ago, DrPhysics said:

Could make for some very scary suicide bombers.

But the Elsecallers possess the ability of Transportation, allowing them to swiftly retreat to Shadesmar.