## Grrl Power #654 – Dejectory

It’s easy to take for granted that smart people in comics (and books, tv, etc) are smart because we see them standing in front of a big board of math – usually a clear board, which looks fancy and futuristic but would probably give you a headache trying to not focus through it. >cough< But the actual smart stuff is always off screen. We never see the process because the writers aren’t as smart as, for example, Reed Richards, who invented a time machine in, like, issue 2 of the Fantastic Four. But even if the writer wants to do a bunch of research just to even have the right equation on the big board for the 0.03% of the audience that would even notice, it’s not like an averagely intelligent character like Sydney would even be able to utilize information like that. (Okay, Sydney has exhibited above average intelligence on occasion, but not “inventing a dimension hopping portal gun” intelligence)

I mean think about it, do you really know what E=MC^2 means? Sure, you know E=Energy, M=Mass, C=The Speed of Light, but without googling it, do you know what the units are? Is E joules or newtons? M=kilograms, probably? And really, if you were on an alien space ship, and you had to program your confiscated railgun with just the right amount of power to punch through the door in front of you, but too little and it ricochets back and kills you, too much and the projectile rips through the bulkhead into space or into the reactor and kills everyone – could you do it? Using E=MC^2. You can’t fire a bunch of shots till you get it right, messing it up kills you at best or everyone at worst, can you tell me you REALLY understand E=MC^2?

Anyway, that’s why I thought this page was funny, because for the briefest flash, Sydney tried to actually mathematically work out space travel in her head. Dabbler would be all “Yo I got this.” but have you guys seen Hidden Figures? NASA had buildings full of really fucking smart people and it took them months to figure that shit out. (And a computer that could do over a thousand computations per second, watch out!) Sure, they were concerned about fuel and oxygen and angles of launch and reentry, and Sydney doesn’t have to worry about any of that. But STILL.

BTW, I know Sydney says it took the Apollo missions took three days to get to the moon, comments on the previous page mostly said four. The point is, Sydney doesn’t have access to the internet and she’s mentally breaking down already.

Double res version will be posted over at Patreon. $1 and up, but feel free to contribute as much as you like.

My understanding of E=MC2 goes as far as “matter is a highly compact form of energy, therefore, if you are telkinetic, you can perform a Kamehameha wave.” Also, “you can rip apart matter to get energy, and if you have enough energy, you can turn it into matter but I only have weird probably-bogus notions of how to do either one.”

e=mc^2 is the “rest energy” of matter. The specific term comes out of an infinite-series exact approximation (when you go through the entire infinite series it’s exact, but… well… INFINITE SERIES. However, the terms become progressively less relevant VERY quickly, unless v is close to c, so you’re unlikely to need more than 2-3 terms from the series to be “close enough”, unless you work with high end particle accelerators or something) of the full energy equation, and e=mc^2 is what you get when you take that infinite-series exact approximation and set v=0 (in which case, it is also exact, because setting v=0 makes all the later additive terms equal to 0).

Hey, congratulations. You understand relativity about as well as anyone who’s not a theoretical physicist or rocket man will ever need to, and more important, you understand that there’s much more to it and that pretending you have those parts figured out is likely to do more harm than good.

you think you hate grinding NOW, try grinding when you have NO idea what your upgrades are! oh, wait, you’re about to x:

Oh you’ve been playing No Mans’ Sky as well.

Basics of Space Flight….

https://www.braeunig.us/space/orbmech.htm

Sadly, if you start getting into any kind of ‘orbital calculations’, you jump into a math a lot deeper than anything Sydney might have been exposed to.

Given the properties of the orbs, none of that applies. And Sydney doesn’t know her top speed in vacuum. If she has a top speed and mach 4 isn’t just where the orbs acceleration matches wind resistance.

Ah, so more ‘Heavenly bodies”, who could say no to that?

Not I. Sydney looks hot!

When Dave told us that the second book* would cover Sydney’s basic training, I kind of envisaged the things we started to see, like her running the assault course and doing orb testing (in the pool, with Maxima initially).

I could not have called it as,

‘using applied gaming 101, whilst in orbit above a destroyed alien homeworld, and evading enemies firing nuke-like weapons at her’!* The first one having concluded when Sydney went to sleep, on the first day, if I recall correctly.More interesting is that this is only day 5 since Sydney became Halo. It’s been a hell of a week for her and there’s still 2 days left.

I’ve always wondered how Reed Richards managed to find time to invent ANYTHING, given the amount of action going on in that universe in a typical day.

Day 5 since anyone else has known about the orbs. I’d honestly say that she became Halo the day she got the orbs, she only got the name and the paycheck 5 days ago.

It is not the first time such an observation has been made. In an earlier post, someone thought that at least one of us was Dr. Michio Kaku; as far as I know, he has not commented here, but there are a bunch of us with math and science training/experience/careers.

E=MC^2 means that a persons mass and weight would constantly double if you ever reached the speed of light, not to worry though, due to all the particles you would crash into you would disintegrate due to nuclear fission and cause a nuclear explosion LONG before the resulting mass gain would be a threat to the universe at large.

The MC^2 term is the bit that relates to the object’s rest energy, does not change with velocity. Also mass does not double per second, it approaches infinity as v approaches c

Relativistic kinetic energy is e = myc^2 – mc^2, where y is actually a gamma symbol and is the Lorentz factor 1/(1-v^2/c^2). It is this that tends to infinity as v nears c and is also the factor to calculate time dilation, distance contraction etc.

Translation to high-school physics – it is the inertia that increases with speed

e^2 = m^4c^4 + p^2c^2

that last bit goes to zero when at rest and is where we get the classic e = mc^2 from

You don’t actually need to know the units, if you’re only using it for your own purposes. You can invent your own, as long as you remember to calculate them through from the ‘base measurements’. Like, if I define V=(‘delta’-D)/T, where delta-D is change in distance, T is time, and V is velocity, I can arbitrarily decide I want my distance in meters and my time in hours, in which case I’d get a V measured in meters per hour. The same should apply to E=MC^2, in that you get an Energy measured in the mass-unit times the velocity-unit, and as long as you’re only using it for your own calculations (and you keep the units standardized to reduce the chance of mistakes) that should be perfectly fine.

Yep, it literally does not matter what units you use: If you multiply a mass by a squared velocity you will get an energy unit.

It might be a silly energy unit like slugs*Smoots²/2112 playings², but it will be an energy unit.

2112 is on my top 10 list of albums and is very appropriate for this scenario

A slug is defined as the mass that is accelerated by 1 ft/s2 when a force of one pound (lbf) is exerted on it. [science of flight]

One smoot is equal to Oliver Smoot’s height, 5 feet 7 inches (1.70 m). [MIT+Beer]

I’m just worried… She has a top speed, but she’s in space… how does that even work? What is her speed relative to?

The body which is having the most gravitational affect on her would be the most logical option. Especially as her flyball clearly can set its own local gravity, in any orientation it chooses. So provides an association which can be used to rationales it.

If Dave goes with that option then it would be relative to the planet for a long time, until she reached the point where the moon’s gravity was having a slightly greater effect on her, than the planet. At which point her speed would be relative to the moon.

Her speed limit (if any) would have to be relative to whatever planet she is nearest to. Everything in space is whipping around at some pretty good speeds, and Mach 4 would leave you damned near motionless compared to everything else. For example, our entire solar system orbits around the Milky Way with a linear velocity of about 1/1300 of SPEOL (230 kilometers per second/143 miles per second). The Milky Way itself is moving towards the Andromeda galaxy at about 130 km/s and the local group of galaxies is moving towards the constellation Hydra at about 600 km/s.

A fixed upper speed limit only makes sense if you have something you can define as the fixed point you are measuring your speed against. Within a planetary environment the planet itself provides that fixed point, and atmospheric drag imposes the limit.

Mach 4 is about 0.85252 miles per second

Oh boy DaveB is super sneaky.

One of her fly/shield (bet shield) Orb effects is: Control of Kinetic Storage, generation(power orb)? and Release. It can store, and release kinetic energy as needed. I also have a sneaking suspicion that it can be generated as well.

For any doubt on how it has worked elsewhere talk to Anvil.

Dabs comments directly on it. – See the fight with the Metal-golem-squid entity at that warehouse they found Sciona draining people of blood.

More importantly if halo can accelerate to mach four and escape orbit it seems in the span of seconds in the vacuum of space shouldn’t she be able to accelerate to her bodies limit or beyond ? Ie. s butt load faster than mach 4 because no friction

So, I don’t know if this is an error, or a reveal on Flight Orbs powers, but Sydney’s observed speed of Mach 4? Way below Escape velocity. Escape Velocity for the Earth is more like Mach 30.

So the orbs doing something funny if she got all the way up there.

The Flight Orb also negates most of the effect of gravity on Sydney. That’s why she can hover, but her hair doesn’t stand on end. She has also demonstrated being able to fly upside down. So she doesn’t need to reach “escape velocity” because she dean’t need to concern herself with gravity pulling her back down.

Plus, as evidenced by the fact that the moon is still really far from her, she’s a long way from escaping the planet’s gravity well.

Also it is assumed that this moon is the same size and distance as our own – and we all know what happens when we assume?

Sydney can hover, so the fly orb does not care about gravity. She could leave the planet at walking speed.

Escape velocity is the velocity (specific speed and direction) that you have to achieve (at a specific given point) to escape a gravity well without further input (e.g. thrust). This means that for as long as Sydney’s flight orb can provide input sufficient to continue increasing the distance between her and the centre of a gravity well, the specific escape velocity she needs to achieve approaches zero.

TLDR, Sydney’s flight orbs laugh at the limitations of primitive chemical rocketry.

Basically this. Sydney’s flight orb provides apparently infinite reactionless thrust, so she can leave Earth’s gravity well at whatever velocity she pleases.

Oh boy DaveB is super sneaky.

One of her fly/shield (bet shield) Orb effects is: Control of Kinetic Storage, generation(power orb)? and Release. It can store, and release kinetic energy as needed. I also have a sneaking suspicion that it can be generated as well.

For any doubt on how it has worked elsewhere talk to Anvil.

Dabs comments directly on it. – See the fight with the Metal-golem-squid entity at that warehouse they found Sciona draining people of blood.

Gee funny how the equations for E = m * c ^ 2 look suspiciously like the ones for Kinetic energy and motion: K= 1/2 * m * v ^2. There are General and Special relativistic versions for kinetic energy too.

https://www.khanacademy.org/science/ap-physics-1/ap-work-and-energy/kinetic-energy-ap/a/what-is-kinetic-energy

fudge the links got mangled

Here comes the Wha-BOOM!

https://www.grrlpowercomic.com/archives/2481

Relativistic Kinetic Energy

https://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/releng.html

https://www.khanacademy.org/science/ap-physics-1/ap-work-and-energy/kinetic-energy-ap/a/what-is-kinetic-energy

E=MC^2 is a highly simplified form of the actual equation, call it the TL;DR version, not what “real” scientists would use to derive useful results. As long as certain constants baked into the E, M, and C values are adjusted for whatever measurement system you are using, you can use any measurement system you care to.

To clarify the equation is energy = mass * A CONSTANT ^ 2

Since in other equations C is the speed of light they assume its the same here. C changes based on what units you use for energy or mass. Basically what it means is as the mass changes, energy changes by the square of the change.

I.E.

Mass*3 = energy*9

Mass*25 = energy *625

Twice now i’ve gotten a virus warning from my antivirus on here just now.

“https://www.webcomicz.com/images/rank/2342-88.png” this is what it said the second time but that’s about all i can really tell besides it saying its some kind of phising thing.

Briggs –

I can’t swear to it being a virus or trojan horse, but I was getting some radically lengthy download times while trying to look at comments for the past 2 days. I think there may have been an ad that was taking a suspicious amount of time to load. Today, however, it seems much better.

“I mean think about it, do you really know what E=MC^2 means? Sure, you know E=Energy, M=Mass, C=The Speed of Light, but without googling it, do you know what the units are?”

I mean, yeah, I do.

I definitely wouldn’t use it to calculate how to use a railgun to punch a hole through a door, because it’s the wrong equation to use and someone who understood that equation wouldn’t use it in this situation in the first place…

So, is this then arc to find out what exactly does orange orb do and what name will it get

Navigational computer/AI assistant. I’ve been thinking that every since the idea of the orbs being a ‘space ship’ came up.

Sydney still hasn’t tried the PPO out on the aliens. Technically, they shot first, so she could claim self defense if it came down to a galactic trial.

Point granted… I would be more worried about the people who she shot at, if they were the same ones who wiped out the Alari, to say “You shot at us…. your world is next on our list!”

“could you do it? Using E=MC^2. You can’t fire a bunch of shots till you get it right, messing it up kills you at best or everyone at worst, can you tell me you REALLY understand E=MC^2?”

Well as someone noted above, not sure how that’s going to help here, not unless your railgun fires antimatter pellets! And yes I do understand it, I could probably still derive E=mc^2 with a bit of effort, it’s not actually that difficult, the maths is no more than UK A level (17-18 age), the key part is working with the assumption that the speed of light is constant for all frames of reference and it mostly falls into place from there. (Special relativity anyway, general relativity where you deal with non inertial frames of reference – ie accelerating or rotating is much nastier maths).

I did do a physics degree though, and haven’t

entirelyforgotten the contents of it :-)Avast sadly detects a phising attempt and contains the threat whenever I get onto this site since a few days ago.

Is it just me or do we see sydney’s ecstasy face in the last panel? I mean not intentionally but instead of an ugh face. It’s more of a Aaaunh face.

Panel 5 is probably my favorite Sydney to date.

I feel the first thing she needs to do is break out the duct tape and start strapping in that shield orb. She is NOT in a good spot to be managing her orbs in an absentmindedly multi-task manner like this.

Sydney needs to remember the most important equation in a situation like this:

E=MC Hammer

Belated random thought, she has an orb that lets her teleport right? I wonder what the range on that ability is. Could she have theorhetically teleported herself to the moon?

“Mega-nega Squidward” made me laugh :D

I’m SURE someone has pointed it out in the comments before me, but I am late to the party and too lazy to check so, here goes:

The path taken by the apolo astronauts to the moon is actually a figure eight. They shoot for a spot ahead of where the moon will be, in order to be able to make corrections, because if you try to catch it on the receding side and miss, there is no way you’d ever be able to catch up.

Correct about the figure-eight transfer orbit, but course correction wasn’t the reason for doing so.

The lowest-energy path (i.e. best fuel/payload ratio) from Terra to Lunar orbit goes through the ‘balance point’ on the direct line between their centres. Taking the old rubber-sheet visualisation, it means going across the saddle between the wells rather than up the flanks of the hills either side. That gives the path a sort of symmetry: a spin-North path around Terra (to take advantage of the boost from its own spin-North rotation) becomes a spin-South path around Luna*. Which becomes a spin-North path around Terra again on the return trip, minimising the deceleration required for a safe landing.

*Right hand rule. Hold your right hand such that the ship would run from base to tip of your fingers as they curl along the path of its orbit, and see which direction along the axis your thumb is pointing.

It’s also used to assign ‘compass’ directions on rotating bodies, by substituting the ship for a point embedded in the body: thumb points North, base to tip of fingers is West to East. Which can get confusing if you have to work with both feet-in (e.g. planets) and feet-out (centrifugal ‘gravity’) reference surfaces.

That last panel is DOPE.

I wonder what the concentration of stem workers/students is in the audience…

I LOVE grinding!!

I just did the math and I think it would take her at least 78 hours going Mach 4 continuously

So she’s going roughly the same speed as Apollo 11.

If this planet-moon system is similar to ours, Sydney could reach this moon in 5 and a half days, going at Mach 4, give or take some hours to account for the moon’s rotation around the planet.

Einstein isn’t going to save the day. His most famous equation is so famous because it’s so concise — by EVERYONE’S standards, most especially by MATHEMETICIAN’S standards — but that doesn’t mean it’s the meaning of life or globally applicable to solving every problem, or even every theoretical physics problem.

Believe it or not, mathematicians’ goal isn’t to gobble up all whiteboard real estate. Simplifying a complex problem down to a full byte expression is their academic field’s Holy Grail.

Anyway, the practical solution to Sydney’s problem is still the same course she’s taking. Thrust to full velocity, then let go of the flight orb go until she needs course corrections. She’ll have plenty of time to play with her other balls before she reaches her destination.

The equations are actually not that hard to understand. Just remember there’s a difference between “simple” and “easy.”

well, without the gravity slingshot, she would reach the moon in about 3.5h approximately . that’s really fast, for planet-side travel

Assuming constant acceleration it’s actually a really simple problem. 0.5*a*t = d

Half of the acceleration divided by the distance is equal to the time

With constant velocity, it’s just t = d/v

Time is equal to distance/velocity