Dash Lambda

The critical thing to clarify here is that 'bounce' means absorption and re-emission. A photon cannot simply hit something and change direction as it always travels in a straight line through spacetime, each time it bounces it's actually a different photon going in the new direction. I agree that the path it takes is also significant in the propagation speed, I forgot about that.

It's not cheating, it's an observation and a foundational assumption that abruptly made our models categorically more powerful and accurate. Have we dipped our hands into the great glowing coils of the universe and found the line in reality's specs that says the speed of light is constant? No. Does everything work out eerily well when you consider the speed of light constant? Yes, to the point that it's integral to most of modern physics. Could we be wrong? Sure, that's how science works. Do we have any indication that we're wrong so far? No, it's just counterintuitive at first. They don't, the ones we detect generally go something like 99.999999999999% the speed of light. In fact, neutrinos reaching the surface of the Earth is an excellent example of something only GR can explain. Their lifetimes are so short that in classical terms they should decay in the upper atmosphere, but because they travel so close to the speed of light time dilation extends their lifespan long enough for them to hit the ground.

I feel like this phrasing is a little misleading. Light in transit, as far as we know, only and always travels at exactly c. The propagation of light through a medium will be slower because it is absorbed and re-emitted by anything in its path. So it's not that the speed of a photon is lower, it's that it turns into a chain of photons going from atom to atom with tiny pauses between being absorbed and emitted. As for the question of why, there are many different ways to approach it, and we can answer some of them. - What makes a photon different from, say, an electron? An electron has rest mass, whereas a photon is massless. So, while an electron can exist at rest, a photon can only exist when moving, and so it must be moving relative to all inertial reference frames, which means it's moving at the speed of light. - What makes a photon travel at the same speed from every perspective? There's a fundamental connection between time and space that distorts concepts like duration and distance with respect to velocity and energy, where other features change to keep the speed of light constant. - What is the purpose of a constant speed of light? Physics cannot answer that question. Not because physics as an entity is insufficient, but because the field of physics describes how things work, it doesn't address the meaning behind them. That's an engineering question, you'd have to ask the engineer who built the universe... whatever that means...

Actually, there's nothing special about light aside from its abundance and interactivity. There are other particles and phenomena that travel at the speed of light, but photons are the easiest ones for us to play with, so we focus on light -hence the name 'speed of light'. If you have mass you cannot travel at the speed of light, because accelerating to the speed of light would require unlimited energy. Things that travel at the speed of light are thus massless, but they have energy due to some weird phenomena that I'd have to read up on again, but the root of it is that they're traveling at the speed of light. So, in order to 'exist' you need to represent some quantity of energy. If you have mass you have energy, and if you have no mass you must be traveling at the speed of light to have energy. As for the second question, yes, if you traveled from A to B at the speed of light, from your perspective it would be instantaneous.

Light travels at the speed of light relative to everything -so when we observe light, to us it travels exactly 299,792,458 m/s. If it's coming out of a moving flashlight, no matter how fast the flashlight is moving, the light is always going at the speed of light. That's why we get red/blue-shifting, because the wave gets stretched out or scrunched up. Now, if you were to think about a photon's perspective, no time would pass. Photons don't change or evolve, they don't change direction (light bending around planets and stuff is technically it following a straight line, but that's GR being weird), they just appear and disappear. There's an effect that comes out of special relativity called length contraction, where the faster you're going the shorter distances appear to be, and due to length contraction, a photon would perceive the universe as totally flat, with no distance between where the photon begins and ends. Physicists don't like referring to a photon's perspective, though. As I understand it, anything traveling at the speed of light doesn't actually have an inertial reference frame, so it can't be an 'observer' in the same way a slow-moving object can. So back to the bus thing, if you have a bus going 99% the speed of light and you shoot a laser towards the front, the photons will still be going at the speed of light from every perspective. To someone outside the bus the frequency of the light is shifted super high, but to an observer on the bus the frequency is 'normal'. You can connect these two perspectives with length contraction -if you think about the light as a sine wave, then both observers see the same number of ups and downs, but the external observer literally sees a shorter bus, squeezing those waves into a shorter length. If you extend that behavior to a bus traveling at the speed of light, then the bus would have no length. That means the external observer would see the photon and the bus travel together, at the same speed.

Think of it like this: You're always traveling at a constant speed relative to anything around you through spacetime. If you're standing 'still' relative to something else then all of your speed is pointed in the time direction, and if you're traveling at the speed of light relative to something then all your speed is in a space direction. The math actually works out that way, that visualization was presented to me as the "spacetime speedometer." Newtonian mechanics isn't sometimes wrong, it is wrong. But it is an excellent approximation of GR at very low relative speeds, so close that there's really no reason to go through the more intensive GR calculations unless you're working over very long length or time scales or with speeds that are a significant fraction of the speed of light. The fact that there is a relationship between time and space is 100% correct, and GR has so far proven to be an excellent model of that relationship. But, while it has given us extremely accurate predictions, you should never consider a model 100% accurate -our understanding of how things work is constantly evolving, and our models are too. Currently there are still questions about the relationship between GR and QM, and some of their predictions differ; neither GR nor QM are likely the final form of our models. We're probably going to see them turn into bigger, more powerful, more descriptive models down the line.

That Zenith Lab compliant escapement is one of the most mechanically interesting movements you can get right now.

Well that's flattering X3 I've only been at this for a year or so, I consider myself a hobbyist. It's a 1913 Hamilton 974 16S pocket watch movement, 17j, open face, all American made.

I'm gonna have to disagree with you on that one. Classical physics tells us that the physical interactions and phenomena that make up... well, us, are described by a set of purely deterministic rules. Thus, if you gathered enough information and used a sophisticated enough model, you could perfectly predict future events, including people's ostensibly independent decisions. Quantum mechanics introduces randomness. We have ways to constrain that randomness, but we have not yet been able to make QM deterministic, and there's active debate over whether that's a matter of our understanding or simply the nature of physics. By QM, no matter how much information you gather, you cannot perfectly predict the state of a system at arbitrary time scales. At best, you can predict a set of possible states. When considering the feasibility of free will in this context, the question becomes where does that randomness come from? No matter how much people claim we're nothing but highly ordered chemical reactions, there remains an element of consciousness that we have yet to even develop the language to describe rigorously. The physical body accounts for all observable behavior, but does not in any way we know account for how you experience the world as an entity through that body. It's not something expressed through any known physical phenomena, and is thus not observable or predictable -it's just a property of your experience. Some describe that (rather uselessly) as your "soul". Some say it's an emergent property of physics, but that doesn't type-check. Ultimately, we haven't even begun to approach understanding it, all we have are names. And that leaves room for stuff to get weird and metaphysical. Maybe you actually are some more abstract entity controlling your body through quantum randomness, maybe reality doesn't exist and all those (apparently nonexistent) old philosophers were right, maybe the answer is even weirder.

Here's my 974 (parts movement) in a 3D printed movement ring. For some reason after I added a back lid to it the movement stopped fitting, gotta figure out what the hell I did. For now it's sitting in the original ring-only model. Anyway, while I have to dial in the dimensions again, currently my case has a movement ring and a back, from there I need to make the crystal ring, put threading (or some other mechanism) on the front and back, and add a pendant. Soooo... guess I should order some crystals and stems.

I haven't read through the whole thing, but I think the topic is a bit interesting. My take is this: To the person who's immortal, their life is less meaningful. Without finite time, there's a lot less pressure to make the most of it -thus a lot less value in your time. However, as an entity, an immortal would represent so much experience and potential that there's hardly even comparison.

As far as I know, yes! Apparently he kept it well maintained (and wore it every day for 30 years). After he died my father kept it in a display case for 20-30 years, and before I started wearing it I got it serviced by our local watch shop, they didn't replace any external pieces. The lume has definitely seen better days, but other than that it's awesome. I just realized, though, that that picture is from before the most recent service. It came back looking pretty much the same, just running better.

HOW DID I NOT SEE THIS SOONER Here's my current best project watch, a 1912 Illinois grade 304 17j in a gold-filled B&B Royal case. It's actually the third watch I've serviced, I have a couple more in progress waiting for parts (in particular, a 1905 Hamilton 992B that's missing a screw I totally didn't fumble and launch god knows where in a cluttered, carpeted room). I haven't done much with watches in a couple months since the best way to get good movements is without cases, and cases for those caseless movements are... hard to get. I've since got a 3D printer and am in the process of designing a 3D printable 16S pocket watch case before I buy up more movements to dig into. And here's my current daily wear, from my grandpa (who received it from my dad and uncles as a gift). It's a 1967-ish Hamilton Thin-O-Matic.

Indeed it can! Quite a simple one actually, as there are constant rates of change. The gap between your place on the stream and the stream's current time increases when the stream moves forward and decreases when you move forward, meaning the rate of change is the difference between the stream's speed and your playback speed, which we'll say are 1 and r respectively. Thus, the equation becomes: g' = 1 - r Quite simple! To solve, just integrate for: g = (1 - r)*t + g0 In this context, the constant of integration represents the initial gap. To solve for the time to close the gap with respect to the length of the gap and the playback speed, set g=0 and solve for t: t = g0/(r - 1) Thus, for a stream where you're 300s (5m) behind with a playback speed of 2, the time to catch up is 300/(2 - 1) = 300s. Sorry I'm late, I need to start checking here more often again!

I posted my desktop earlier, but I've seen some phone homes so I figured I'll share that too:

Honestly, to me, black ThinkPads are aesthetically unmatched. I don't understand the whole bead-blasted aluminum plate look.

@EpiCheeseTime New one just came in, and it works. I'm moving in as we speak (and will probably not be done for another day or so). It really was just two DOAs in a row, from two different retailers. I'm not really sure how I feel about that.

Instructions unclear, mind downloaded onto hard drive. For real though, I just sent the drive in for a replacement. I'll put here whether or not the next one's a DOA. If it is, then... uhm... no clue. Seems unlikely. Even more so than two.

@emosun@Kilrah@EpiCheeseTime I just tested it with my brother's USB SATA dock, starts clicking furiously and beeping before totally shutting down, still won't show up.