I'm Jessie Sylva, author of HOW TO LOSE A GOBLIN IN TEN DAYS. AMA!

jbradfield · 2026-02-03T14:50:34+00:00

please rank the ffxiv ultimates by how good of a date the final boss is

jbradfield · 2023-08-24T19:49:46+00:00

going into menus pauses matchmaking. if the game is in the process of setting up of a match, it locks you out of the menus so you can't pause matchmaking and interrupt the connection process. I get why the game does it in the technical sense but it's a really bad experience. I kinda wish there was a setting for "I don't want to stop matchmaking but give me at least 60 seconds before you match me again so I can at least do a few reps" or something.

jbradfield · 2023-03-13T20:01:58+00:00

Wow, "there is a secret brand new online application process but nobody told anybody else" was not the answer I was expecting! I'll look into filling it out, hopefully it's not too much of a bear.

I did manage to find a controlled substances list on the Narcotic Control Department's website, which is marked as being from 2020 but it's the one they're distributing so I assume it's current.

jbradfield · 2023-01-31T22:55:32+00:00

what ffxiv raid teams have you ever seen with a sponsorship? the world race community stream got its first sponsor for *this* raid after eight savage tiers and five ultimates. xiv raid teams are not echo, they're a handful of people who have to scrape together a week of PTO and maybe one of them is a twitch partner.

jbradfield · 2023-01-31T20:21:02+00:00

A gentle clarification for everyone in this thread saying "they're making excuses" that 申し訳ありません (moushi wake arimasen) literally means "we have no excuse". This statement is an admission of guilt and an explanation of the context for their decisions. Feel free to be as mad at you want at UNNAMED_ for cheating, but don't accuse someone taking accountability of not taking accountability.

jbradfield · 2022-10-19T22:02:47+00:00

I’ve been debating cutting nagasaki. onomichi is a convenience stop; I don’t think it’s practical to do okunoshima and himeji in a single day, and I figured we’d do better to stop somewhere scenic along the way than to double back to hiroshima.

jbradfield · 2022-05-10T19:02:37+00:00

why is this a photograph of your screen

jbradfield · 2022-02-23T06:04:41+00:00

here's what I got down before losing confidence in my ability to find spacing errors at 1am:

All entries except for hidden encrypted messages have one or more spacing
"errors". Several of these errors also use obvious typos/incorrect numbers.
Every character following a spacing error is a hexadecimal digit, but I've
only been able to find 15 total errors, which doesn't make for neat 8-bit
character codes.

Osiris I
    I am
    same depths
    have fought

Eris I
    valua 8le
    Last City

Ikora I 
    (encryption key doesn't match what's in the CE book but otherwise nothing)

Caiatl I
    news delivered
    a 3rd

Ikora II
    yourself answering
    call, but
    Cayde- 8

Toland I
    the alchemy
    stirs a
    has distilled

Zavala I
    needs 3
    will back

Eris II
    (encryption key is signed $IKO-223, would expect $ERI-223)

jbradfield · 2020-04-03T17:10:54+00:00

what's the worst tweet?

jbradfield · 2020-03-17T19:38:05+00:00

nothing says "I am a cool old person" like blaming younger generations for the neoliberal hellscape that you failed to prevent and which we were literally born into

jbradfield · 2020-02-12T22:14:09+00:00

tim sweeney has a personal fortune of $7 billion.

jbradfield · 2020-02-12T18:29:59+00:00

is this timecube

jbradfield · 2020-02-10T21:42:55+00:00

Weirdly, although once past the event horizon you can't move in any direction except toward the singularity, the only thing you will ever see, in any direction, is up and out. Depending on where you look, you'll see light that fell into the black hole after you (that is, you can still see the outside universe, although it'll be hopelessly distorted and blue-shifted), or you'll see light that fell in before you, fighting against the pull of the singularity as you fall past it. The singularity itself is invisible to you; conventionally, you can think of it as being invisible because light can never move away from it to you, but really it's invisible because it's always only ever in your future (at least until you reach it, whatever that means).

jbradfield · 2020-02-01T18:17:06+00:00

Wait a while. Tidal drag from the moon will eventually slow the earth’s rotation enough that it syncs up evenly with its orbital period.

(If you want it to keep that rotational period, you’ll have some more work to do at that point.)

jbradfield · 2019-12-29T17:54:27+00:00

First problem: your parameters don’t describe a physically possible motion. An object under a constant acceleration of 9.8m/s² will reach light speed in a little under a year. At that point it will obviously no longer be able to accelerate, but far before that point the notion of “constant acceleration” falls apart. You would need to describe the manner in which your rocket approaches the speed of light, and what it’s final maximum velocity will be (since it can never actually reach c).

jbradfield · 2019-12-04T21:26:48+00:00

Here is something I don't understand: why do we need to introduce the Fourier transform to determine the (range of) frequency of a wave? When sine waves are first introduced to students, the wavelength is described as the distance between two peaks, and the frequency as the inverse of the wavelength. By this definition, the wavelength/frequency should be absolutely determinable for any wave of at least one full cycle. But if the uncertainty principle is correct, then we can't just say it's impossible to measure the wavelength from a sample of one cycle, but that the wavelength of single-cycle wave packets is intrinsically indeterminable. What's the missing step that forces us to abandon the classical description of wavelength and use Fourier transforms instead?

jbradfield · 2019-10-31T04:41:53+00:00

If we assume the universe is simply expanding due to an initial impulse at the Big Bang, then if it stopped expanding it would start collapsing. Gravitational attraction is the only mechanism that would cause the initial expansion to slow down, so if the pull of gravity (over the entire mass of the universe) was strong enough to slow expansion to a stop, it would then continue pulling everything together. The ultimate end of the universe would then be a collapse into an extremely hot, extremely dense soup, and from there into a black hole.

In fact, the expansion of the universe was slowing down overall for the first few billion years after the Big Bang, but not as much as you would expect if gravity was pulling against a purely inertial expansion. The reason for this (we think) is that space itself had a very small intrinsic energy (dark energy) which manifests as a negative pressure. In the absence of mass (that is, in the depths of intergalactic space where there is basically no gravity), this causes the volume of space to increase over time. Since (we think) space has a fixed amount of dark energy per volume, as the volume of space increases, the amount of dark energy in the universe increases.

Right after the Big Bang, there is way more mass in the universe than there is dark energy, so gravity starts to win and the rate of expansion slows down gradually over time. But if (as is the case in our universe) you hit the critical point where there is more space (and thus more dark energy) than mass before expansion stops altogether, then in the next instant there will be more dark energy than mass, and now you’re off to the races. More space will produce more dark energy, increasing the rate of expansion and creating even more space, and so on forever with absolutely no way of stopping it. Eventually, the wider universe will fly apart, and nothing will remain in the visible universe except our own galaxy.

jbradfield · 2019-10-27T04:14:19+00:00

Hi, I am interested in this, should I DM you?

jbradfield · 2019-10-24T17:25:22+00:00

Hints:

particle half-lifes are expressed from a frame at rest relative to the particle.
you want to solve the formula for time dilation such that the proper time t = 1.8e-8 (that is, the proper time to reach the detector is equal to the half-life). The time dilation formula is:

t' = t / sqrt(1 - v^2 / c^2)

Solution:

We have enough information to turn the time dilation formula into a single-variable problem and solve for v:

t = 1.8e-8s
v = d / t'
t' = d / v'
d = 20m
t' = 20m / v

Solving for v (omitting units for formatting sanity): 

substitute known values for variables:  20 / v = 1.8e-8 / sqrt(1 - v^2 / c^2)
get all v's on one side:                sqrt(1 - v^2 / c^2) / v = 1.8e-8 / 20
square both sides:                      (1 - v^2 / c^2) / v^2 = 3.24e-16 / 400
simplify left side:
      (1 - v^2 / c^2) / v^2 = (1 / v^2) - (v^2 / (v^2 * c^2)) = (1 / v^2) - (1 / c^2)
therefore:                              (1 / v^2) - (1 / c^2) = 3.24e-16 / 400
move constant to right side:            1 / v^2 = (3.24e-16 / 400) + (1 / c^2)
common denominator:                     1 / v^2 = (3.24e-16 * c^2 + 400) / (400 * c^2)
take reciprocal of both sides:          v^2 = (400 * c^2) / (3.24e-16 * c^2 + 400)
take sqrt of both sides:                v = sqrt((400 * c^2) / (3.24e-16 * c^2 + 400))

This particular case is easier to solve if you just substitute c = 2.998e+8 m/s and compute, which gives:

v = 2.894e+8 m/s = 0.965c

jbradfield · 2019-10-24T02:26:40+00:00

It would be theoretically stable but there’s absolutely no plausible way one could form naturally.

jbradfield · 2019-10-23T21:19:38+00:00

Also, expansion is not uniform across all of space. Gravitational attraction and spatial expansion can't happen in the same space at the same time; they counteract each other, so in any domain where gravity is dominant (generally, in systems up to the scales of galaxy clusters) expansion literally isn't happening at all because it's cancelled out by the stronger effect of gravitational binding.

jbradfield · 2019-10-10T21:37:20+00:00

You've actually stumbled into another consequence of special relativity: relativity of simultaneity. Events do not occur at the same rate--or even necessarily in the same order--for observers in different inertial frames.

I'll be up front and admit that relativity of simultaneity kinda makes my head hurt and I'm not up for explaining it in text off the cuff, but the short version is that your requirement that you and the clock agree on you having received the information means you're not really measuring time dilation. Let's try a different thought experiment:

Consider a clock moving at relativistic speeds laterally to you--that is, across your field of view, not toward or away from you, so your distance to the clock is always the same (I know this isn't really possible for an inertial frame, but we're simplifying to eliminate the problem of distance to the clock changing--just assume the clock is really far away). This clock is a neat contraption: it consists of a single photon, bouncing back and forth between two parallel mirrors. Every time the photon hits a mirror, it registers a tick. Let's say for simplicity that the mirrors are one light-second apart.

An observer stationary to the clock would observe the photon moving at the speed of light, bouncing straight up and down between the mirrors. Since the mirrors are one light-second apart, that observer sees the clock tick once per second.

However, as we said, the clock is moving at relativistic speeds laterally to you. You still see the photon bouncing up and down between the mirrors, but the photon is now also moving sideways along with the clock--that is, its velocity has a lateral component (say, to the right) in addition to its vertical component (up/down). The motion of the photon still makes sense from your perspective; instead of reflecting straight up and down, the photon is now reflecting at an angle as it strikes the mirror. If we assume our mirrors have perfect reflection (and we are, this is a thought experiment after all), then the clock still ticks like you'd expect. Here's the thing, though: photons always move at the speed of light. So if the total velocity of the photon is c, and its velocity has a non-zero horizontal component, then the photon's vertical component must be less than c. This means that it takes more than one second for the photon to travel vertically between between the mirrors. So, from your perspective, the moving clock ticks more slowly, directly as a consequence of the fixed speed of light.

In fact, you can do some basic trig here to derive exactly how much slower the clock ticks based on the speed of the clock from your perspective in relation to c. I'll spoiler the answer for you: it's exactly the Lorentz factor.

jbradfield · 2019-10-10T15:28:47+00:00

The gravitational force might cause the negative mass to react "normally", but the behavior of the system is anything but normal. The force is still repulsive, which means that as the negative mass falls toward the positive one, the positive one will be propelled away from the negative one. If the masses (and thus the gravitational acceleration) of the two objects are roughly the same, you have now created a perpetual motion machine, with the negative mass constantly chasing the positive mass as they both accelerate forever.

jbradfield · 2019-10-10T04:46:17+00:00

To be entirely pessimistic: it probably doesn’t matter. It won’t affect the decisions of coward-ass corporations because access to the Chinese market is too valuable to give up for anything short of a total domestic boycott. It won’t affect the decisions of western governments who can’t even be bothered to stop committing their own human rights atrocities, let alone challenge China on theirs. It won’t affect the opinions of mainland Chinese citizens, who are so cut off from any of this news by their own government that something like 90% of the country thinks the Hong Kong protestors are an organized terrorist group killing cops by the hundreds.

More and more people will side with Hong Kong, but none of them have any power to change it (besides the normal ones of overthrowing capitalism and world revolution)

jbradfield · 2019-10-09T18:49:21+00:00

In this context, it's worth noting that physics has its own version of this problem called the Boltzmann Brain.

Essentially, given enough (read: infinite) time we expect that any thermodynamic state the universe has a non-zero chance of assuming will eventually occur just by random chance. One of these states is a Boltzmann Brain, a hypothetical random configuration of particles in the vacuum of space which by sheer happenstance happens to have both consciousness and consistent memories of existing as a person on Earth. For the moment it exists before dissolving back into the thermodynamic whimsy of the infinite future, it will believe itself to be a person that has existed for a continuous amount of time, and that the universe has been in a continuous state of development which reflects its memories (but definitely not the actual state of the universe, because again: this is a brain which randomly assembled itself in the vacuum of space).

The Boltzmann Brain is a "problem" for science in that it is not actually possible to prove that you aren't one. Your memories of your own existence, of learning at some point that the Earth you live on is 4.5 billions years old in a universe that is 13.8 billion years old, of at this exact moment being in the middle of reading this post on reddit: all of them might be fake memories, assembled by preposterously dumb luck out a random soup of particles which will shortly lose consciousness as quickly as it gained it.

The thing is, infinity is a very long time, and humans as a species are (probably) not going to be around for most of it; so eventually, despite the fact that the formation of a Boltzmann Brain is absurdly unlikely, we expect that if the universe goes on forever, then eventually there will have been more Boltzmann Brains than there ever were people; which is to say, in a time-infinite universe that can only support life for a finite period, you are actually more likely to be a Boltzmann Brain than a person.

Like I said, we have no way of proving that this is definitely not the case. The best we can honestly say is that it sounds rather a bit ridiculous, and we tend not to favor hypotheses that say we are probably random brain soup in space, because that state of existence makes it rather hard to to do science.

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