Ask and answer stupid questions here! - Page 265

FiWiFaKi

Canada9859 Posts

May 28 2015 06:45 GMT

#5281

On May 28 2015 15:42 swag_bro wrote:

And how can managers check if the waiter/waitress pockets the money or not? I guess the customer should only be allowed to tip in a tip jar at the register or something? I don't know. There is no way to micromanage every single little action like pocketing tip money. Your idea sounds kinda okay in theory but would be extremely difficult to execute and maintain.

And don't say honor system bullshit. In this day and age, nobody is honest. I say just remove the whole tipping bullshit and give waiters/waitresses minimum wage and let promotions to like 'Waiter II' happen and shit like that. Tipping is fucking retarded and I never do it because I firmly believe that waiters don't even deserve it.

Honestly, it's quite easy.

Most bars here have cameras. If someone accused someone else, you can watch the camera, and if it was true, they get a write-up or termination. And if people pay with visa/debit, good luck trying to pocket that.

swag_bro

Japan782 Posts

May 28 2015 06:50 GMT

#5282

On May 28 2015 15:45 FiWiFaKi wrote:

Show nested quote +

Even if there are cameras, they can still be exploited by someone smart. Yeah, credit card tips are a thing, but I often see cash tips more so than credit card tips. People are smart, shady and devious. It's not hard to pocket some money against whatever company policy. Like I said, eliminating the tip thing is the best way.

And anyways, why do we have to tip servers? Why can't we tip baggers or cashiers? Hell, why can't I tip R1CH for making this shitty site?

fruity.

England1711 Posts

May 28 2015 06:50 GMT

#5283

On May 28 2015 15:42 swag_bro wrote:

Show nested quote +

And how can managers check if the waiter/waitress pockets the money or not? I guess the customer should only be allowed to tip in a tip jar at the register or something? I don't know. There is no way to micromanage every single little action like pocketing tip money. Your idea sounds kinda okay in theory but would be extremely difficult to execute and maintain.

And don't say honor system bullshit. In this day and age, nobody is honest. I say just remove the whole tipping bullshit and give waiters/waitresses minimum wage and let promotions to like 'Waiter II' happen and shit like that. Tipping is fucking retarded and I never do it because I firmly believe that waiters don't even deserve it.

Not all payments are cash, the tip amount can be added to the bill, then paid for via card.

helpman176

128 Posts

May 28 2015 06:54 GMT

#5284

Implied cumpulsory tipping creates this culture of artificial friendliness that you can see in the US.
I would prefer the grumpy Viennese waiter over this artificial bullshit anytime!

swag_bro

Japan782 Posts

May 28 2015 07:00 GMT

#5285

On May 28 2015 15:54 helpman176 wrote:
Implied cumpulsory tipping creates this culture of artificial friendliness that you can see in the US.
I would prefer the grumpy Viennese waiter over this artificial bullshit anytime!

Exactly dude. Whenever I go to China and go to the restaurants, they just plop the food down and leave...no smile or other fake shit. If I need them, I wave my hand or yell at them. That's what I pay them for, to take my order and bring the food to the table, not tell ask me about my day and compliment my shirt. They're not my friend nor a psychologist, so they can fuck off.

FiWiFaKi

Canada9859 Posts

May 28 2015 08:02 GMT

#5286

On May 28 2015 15:50 swag_bro wrote:

Show nested quote +

Well the logic is that you tip for a service to get higher quality and give more incentive to the worker. A barber or a server can vary a lot more than that of say a cashier. Like you don't tip your accountant, since you know they aren't going to mess up your taxes if you don't. Likewise, a cashier can't really give you premium service.

A server can, the attitude of the server has a pronounced effect on your experience for example (well a lot of the time), that is the rationale, and thus, those are the industries that are tipped.

Don't get me wrong, I think a no-tip society would be better, but I hope you can see the obstacles that would exist, and the riots that would ensue from this, as surely servers would make less on average.

The nice thing for you is if you don't follow social norms, or don't have much empathy or sympathy for people, then you don't have to tip, and you will get whatever you have cheaper compared to not having tipping culture. Though I've had servers come up to me, and cry for 5 minutes (yes cry), after they had a table of 8 people or something, and a 200-300 tab, without a tip.

edit: As to what I do, I tip like this:
Bad service: 1%
Sub-par service: 0%
Average service: 5%
Good service : 10%
Great service: 25%
Excellent service: 40-50%

I think the most important thing is, don't tip when service is bad. Don't think twice about the food being good, and feeling bad for the cook (most of the time they get little anyway). If we are stuck with the system we have, at least incentive the servers to give you a good experience. If they seem completely fake, try to rush everything quickly, mess up orders, whatever. Don't tip.

Like you know, a server will have puffed up cheeks and be pissed off all night, and then complain that she's getting shitty tips? Good!

FiWiFaKi

Canada9859 Posts

May 28 2015 08:34 GMT

#5287

Oh, so I have a question myself. I have a mech engg degree, so I don't know some of this hardcore physics stuff, but don't need a layman explanation.

I started thinking about conservation of angular momentum, and how the slow moving dust in space collects into a centralized location to make a planet, and due to that, the planets spin - and spin a lot faster than the dust that was initially there. This of course is due to the mass moment of inertia changing, becoming much lower, and thus results in faster angular velocity.

So the two questions that arose from this are:

1) Okay, so given sufficient mass, gravity becomes strong enough to overcome the repulsive force from electrons, electron degeneracy pressure or something, I think is what it's called. So this is what creates neutron stars, and then what opposes the force of gravity is the neutron degeneracy pressure. But as you increase the mass even more, even the neutrons aren't able to overcome this force, and then, as far as we know, the neutron star would collapse into a singularity, as there isn't any other force that could oppose gravity.

From my understanding, this is kind of what a black hole is... But, it being a singularity, means it has a mass moment of inertia of 0... Which would mean that its angular velocity would have to be infinity to satisfy the conservation of angular momentum. So is that the case, how does this all work? The only way I could rationalize it to myself is that there has to be another degeneracy pressure of some sort, and a black hole isn't a singularity, rather a very compact object, like quark-gluon plasma , or something even more fundamental.

2) Okay, this is probably a very easy question to answer, but thinking about conservation of momentum, and how the mass moment of inertia of an object can change, the mass of an object can change also. I figure the reason is because newtonian mechanics don't work at high velocities but:

What would happen if I accelerated say a sphere of Uranium 238 to 99% the speed of light in space. Then as it would undergo alpha decay, helium nuclei would shoot out (I'd assume in random locations), and thus the trajectory of the sphere should not change, and the sum of force would be 0. However, since the mass changed by (234-238)/238 ... Assuming all uranium atoms underwent decay, for momentum to be conserved, the velocity would have to be above the speed of light. How does this work?

3) As I got thinking about black holes, how does black hole radiation work. If photons cannot escape a black hole, hence being black, then how can a photon be radiated outside? Is it that visible light cannot escape black holes due to having lower energy, but gammas or cosmic rays can, or is it something else? Actually there's just so many questions, I don't know where to begin... Like if it's a singularity, wouldn't it eventually cool down completely (no reactions occur?), and then at roughly 0 kelvin, how can it radiate anything, and just yeah, confusing to me.

Shiragaku

Hong Kong4308 Posts

May 28 2015 08:42 GMT

#5288

Is Chill still part of the TL community?

fruity.

England1711 Posts

May 28 2015 08:53 GMT

#5289

On May 28 2015 17:34 FiWiFaKi wrote:
3) As I got thinking about black holes, how does black hole radiation work. If photons cannot escape a black hole, hence being black, then how can a photon be radiated outside? Is it that visible light cannot escape black holes due to having lower energy, but gammas or cosmic rays can, or is it something else? Actually there's just so many questions, I don't know where to begin... Like if it's a singularity, wouldn't it eventually cool down completely (no reactions occur?), and then at roughly 0 kelvin, how can it radiate anything, and just yeah, confusing to me.

Interesting stuff. I have a great interest in science / space stuff. But very much at the casual level. For the longest time I couldn't understand the concept of radiation coming from a back hole. If everything gets sucked in once you pass the event horizon.. Then how?

At the quantum level emptiness isn't empty, stuff pops in and out of existence all the time, and apparently this is ok, but only happens for the briefest of time. Matter is borrowed from somewhere, but then almost immediately cancels one another out. So at the event horizon you have matter popping in and out of existence. Matter and antimatter. The forces of extreme gravity and heat at this point can rip the two apart, one might fly into the singularity, but the other can pop off in the other direction, being released as radiation (I think this is called Hawking radiation?).

So nothing is coming out of the singularity. As far as I know once you pass the event horizon, everything is doomed. But the radiation release happens at the event horizon (or close to it) But never after.

This is my oh so basic understanding, and I too would love to hear other, more knowledgeable explanations. I find this stuff incredibly interesting, but oh so complicated on so many levels.

Cascade

Australia5405 Posts

May 28 2015 09:20 GMT

#5290

On May 28 2015 17:34 FiWiFaKi wrote:
Oh, so I have a question myself. I have a mech engg degree, so I don't know some of this hardcore physics stuff, but don't need a layman explanation.

I started thinking about conservation of angular momentum, and how the slow moving dust in space collects into a centralized location to make a planet, and due to that, the planets spin - and spin a lot faster than the dust that was initially there. This of course is due to the mass moment of inertia changing, becoming much lower, and thus results in faster angular velocity.

So the two questions that arose from this are:

1) Okay, so given sufficient mass, gravity becomes strong enough to overcome the repulsive force from electrons, electron degeneracy pressure or something, I think is what it's called. So this is what creates neutron stars, and then what opposes the force of gravity is the neutron degeneracy pressure. But as you increase the mass even more, even the neutrons aren't able to overcome this force, and then, as far as we know, the neutron star would collapse into a singularity, as there isn't any other force that could oppose gravity.

From my understanding, this is kind of what a black hole is... But, it being a singularity, means it has a mass moment of inertia of 0... Which would mean that its angular velocity would have to be infinity to satisfy the conservation of angular momentum. So is that the case, how does this all work? The only way I could rationalize it to myself is that there has to be another degeneracy pressure of some sort, and a black hole isn't a singularity, rather a very compact object, like quark-gluon plasma , or something even more fundamental.

2) Okay, this is probably a very easy question to answer, but thinking about conservation of momentum, and how the mass moment of inertia of an object can change, the mass of an object can change also. I figure the reason is because newtonian mechanics don't work at high velocities but:

What would happen if I accelerated say a sphere of Uranium 238 to 99% the speed of light in space. Then as it would undergo alpha decay, helium nuclei would shoot out (I'd assume in random locations), and thus the trajectory of the sphere should not change, and the sum of force would be 0. However, since the mass changed by (234-238)/238 ... Assuming all uranium atoms underwent decay, for momentum to be conserved, the velocity would have to be above the speed of light. How does this work?

3) As I got thinking about black holes, how does black hole radiation work. If photons cannot escape a black hole, hence being black, then how can a photon be radiated outside? Is it that visible light cannot escape black holes due to having lower energy, but gammas or cosmic rays can, or is it something else? Actually there's just so many questions, I don't know where to begin... Like if it's a singularity, wouldn't it eventually cool down completely (no reactions occur?), and then at roughly 0 kelvin, how can it radiate anything, and just yeah, confusing to me.

Oh, this question is mine! :D

0) That's 3 questions, not two.

1) After the atoms cannot hold up, the electrons get pushed into the protons, forming neutrons, hence neutron star. The quarks (the elementary matter particle shaping the neutron and the proton) still stay separated in a neutron star. Once you have enough mass to squeeze the quarks into each other, things collapse into a singularity according to the standard model of particle physics, where the quarks are pointlike elementary particles. And this leads to a noumber of infinities as you point out, and is in general a bit of a headache. This is where a theory of everything (ToE) that consistently handles both EM, weak, strong and gravitational force at the same time. Right now, with current physics, we don't know how the "singularity" in the middle of a black hole works, and it isn't very easy to look...

Most solution with exotic physics (strings, whatnot) stop the singlularity from being a singularity as you say. But again, as we can't meassure, who knows.

2) I think the question can be reformulated like this: A spaceship travels at 0.9c (90% light speed) relative to earth. Someone on the spaceship shoots a missile straight ahead that travels at 0.9c relative to the spaceship. Why doesn't the missile travel at 1.8c relative to the earth?

Speed and momentum isn't linear at that high speed. So 0.9c plus 0.9c isn't 1.8c, but more like 0.98c or something. The formula for momentum p as function of speed v is (iirc)

p = m*v/sqrt(1-v^2/c^2)

When v is much smaller than c (ie nowhere near light speed), v^2/c^2 is essentially 0, and the square root is essentially 1, and you reproduce the calssical formula p = m*v. However, for v just below c, v^2/c^2 is just below 1, and sqrt(1-v^2/c^2) is a very small number, thus 1/sqrt(...) is a very large multiplier on top of the classical momentum. As v approaches c, the multiplier tends to infinity. Thus you cannot accelerate things to light speed if m > 0, as it'd need infinite p.

3) Quantum fluctuations. The point of a black hole is that within a certain radius not even light can escape. This is called the event horizon of the black hole. Through quantum fluctuations, virtual pairs of photons and antiphoton (one with positive energy, the other one with negative energy, to preserve total energy. Photons don't like being in negative energy, so they will quickly re-merge into nothing normally) are created everywhere. If this happens close to the event horizon, sometimes the negative energy photon will fall enough into the gravitational well to gain positive energy before it re-merges with it's twin, and then both photons are at positive energy, and don't need to re-merge any longer. The initially negative energy photon that started to fall into the back hole will continue to fall in, the other one will (barely) escape, as this happened just outside the event horizon. While nothing can escape, QM can play a trick drop negative energy photons into the black hole while shooting out positive energy photons. The effect is the same as if the black hole radiated. This is called Hawkings radiation after Theoretical Physics poster boy Stephen Hawkings.

Cascade

Australia5405 Posts

May 28 2015 09:22 GMT

#5291

You got it right fruity.

puerk

Germany855 Posts

May 28 2015 09:27 GMT

#5292

Yes, no, maybe.
You will get many different answers but they will be incomplete or strange simplifications. We can model dust (thats basically what it comes down to in the limit of weak forces compared to the gravity of such a collapse, dust in this context means matter that only has a restmass component in the energy momentum tensor) collapses to a black hole, and with radiation strewn in they still hold. Your question about the singularity is easier to explain: a rotating singularity is ring shaped and therefore can have angular momentum. Furthermore angular momentum can also be conserved via spin for instance even by "point particles" like photons with no inertia. So that understanding of moment of inertia is a derived rule from observations not a absolute law.

Back to black holes: now comes the twist: there are stable solutions to the collapse problem, where even after an event horizon is formed no singularity occurs. This is achived when the weak energy condition is violated, i.e. when for instance quantum gravity effects (which we have no clue how big they are and how to model them) contribute negative mass-energy.

We can be pretty sure that our universe has a lot of at least apparent horizons entrapping parts of spacetime for a "long time", if therin happens a collapse, a bounce, an evaporation, a strange matterstate, we currently do not know.

There was one nice result i read years ago, that for a class of famous regular black holes (such that do not develop a singularity eventhough a true event horizon is formed) the orbits close to the event horizon are slightly different then close to the typical kerr-newmann, so we could actually probe for that.

On May 28 2015 17:34 FiWiFaKi wrote:
2) Okay, this is probably a very easy question to answer, but thinking about conservation of momentum, and how the mass moment of inertia of an object can change, the mass of an object can change also. I figure the reason is because newtonian mechanics don't work at high velocities but:

What would happen if I accelerated say a sphere of Uranium 238 to 99% the speed of light in space. Then as it would undergo alpha decay, helium nuclei would shoot out (I'd assume in random locations), and thus the trajectory of the sphere should not change, and the sum of force would be 0. However, since the mass changed by (234-238)/238 ... Assuming all uranium atoms underwent decay, for momentum to be conserved, the velocity would have to be above the speed of light. How does this work?

momentum is not additive the way you think it is, lorentz transformations still apply
or more elegantly: momentum is not a conserved quantity, 4-momentum is. http://en.wikipedia.org/wiki/Four-momentum#Conservation_of_four-momentum

First of all: Hawking radiation is not classical gravitational physics but quantum corrections applied to gravity. The blackhole it self does not radiate, rather the event horizon makes weird statistical effects at its boundary happen, as both regions are causally disconnected. There are some problems with trying to naively understand blackhole thermodynamics as there are many open questions about it. (Not so long ago Hawking even wrote a paper that black holes maybe do not exist in the sense that all apparent horizons are only temporary and no real event horizon ever forms) Basically the issue is: What happens at the horizon, it has nothing directly to do with mass of the blackhole or even "reactions".
The radiation that escapes is so to say quantum fluctuation particles that steal the black hole energy, but that picture has its trouble aswell because there are no "anti-mass" particles, that you can imagine.

The simplest answer i guess is pick up a book on black hole thermodynamics, go through the calculations, and see that it works out, and wait for the next penrose to come up with a great intuitive explanation what goes on there

puerk

Germany855 Posts

May 28 2015 09:28 GMT

#5293

well i guess "sniped"

Cascade

Australia5405 Posts

May 28 2015 09:39 GMT

#5294

Haha, I'm happy to be on this side of the snipe for once.

fruity.

England1711 Posts

May 28 2015 09:43 GMT

#5295

On May 28 2015 18:22 Cascade wrote:
You got it right fruity.

Thank fuck. My answer is for the casuals, you're for the more eggy heads :D

Black holes. Sexy.

FiWiFaKi

Canada9859 Posts

May 28 2015 09:46 GMT

#5296

Thanks to both of you Cascade and Puerk.

Yeah, damn, it's all so interesting. I wish we had a better understanding of all of this. And it would also be nice if the Standard Model wasn't so ugly.

fruity.

England1711 Posts

May 28 2015 09:47 GMT

#5297

On May 28 2015 18:46 FiWiFaKi wrote:
Thanks to both of you Cascade and Puerk.

FiWiFaKi

Canada9859 Posts

May 28 2015 09:52 GMT

#5298

Oh sorry sorry!

I liked your explanation too! Maybe a bit vague, but it seemed like you were mostly in the ride to see another explanation. Glad you got it spot on though!

fruity.

England1711 Posts

May 28 2015 09:59 GMT

#5299

On May 28 2015 18:52 FiWiFaKi wrote:
Oh sorry sorry!

I liked your explanation too! Maybe a bit vague, but it seemed like you were mostly in the ride to see another explanation

I kind of understand it, but purely on the lite level

There's a real boundary to understanding this stuff, was it Bohr who said on quantum jumps "If you think you have understood it, you haven't thought about it enough". Something like that. And that from one of the greatest Theoretical Physicists ever.

Obligatory: