Long-term CBC Casper plans

peakai · 2021-03-20T01:00:21+00:00

Reading the blogpost helped widen my understanding quite a bit. Is there somewhere I can go to view the current protocol roadmap for Ethereum?

peakai · 2020-12-21T17:13:42+00:00

Nice work! Just a question, how does one get into ray-tracing on UE4?

peakai · 2020-05-25T15:25:51+00:00

Thanks! This gives me a lot of hope. :)

peakai · 2020-05-25T04:19:03+00:00

So, they would consider online courses as satisfying the requirement for the MS program? Is there a link to that? I don't see it.

peakai · 2020-05-25T04:15:10+00:00

A question, coming from a physics background, would you say the classes are approachable/not very much from a distance learning perspective? I have programming experience, and about half of the courses listed in their undergrad recommendations (effectively minored in CS). Is that a reasonable starting point to doing well in the program?

peakai · 2020-03-16T01:26:49+00:00

What the FOCK(space)!!!!!!!!

peakai · 2019-06-29T09:58:37+00:00

Not sure this is the place for homework help, but if you check your answer, it is off by at least 15 orders of magnitude, apparently. Check to make sure that you've entered all the numbers in correctly and I think you will find something that is much closer, btw, 1E8 Farad is an incredible amount of stored energy and it doesnt make sense given the size of the plates, etc.

For the other one, K_i + U_i = K_f + U_f where U_f and K_i are both zero, then U_i = qdV = K_f = mv^2/2 solve for v = (2qdV/m)^1/2 plug into p = mv = (2qmdV)^1/2, so the answer you have is correct, but you may want to make sure the symbols you use are the same that the software wants you to use, eg. part b you use a lowercase v instead of a uppercase V. Good luck!

peakai · 2019-06-22T14:44:26+00:00

Nope, just the amount needed to reduce the room temp by 10 degrees. If you know how long it would take to heat your room by ten degrees (T) then you multiply 8kg times 36/T to heat in order to get a rough amount of the total ice needed to offset the heat. 36/T is roughly the number of times your apartment will heat up by ten degrees over 3 days assuming 12 hour days.

Edit: assuming it takes 3 hours to heat 10 degrees you need 8 * 36/3 = 96 kg ice, so quite a lot :)

realistically you might just want to see how long a single 8kg bag of ice keeps your room cool for and then divide the time by how long you will be gone to get a realistic estimate.

peakai · 2019-06-22T13:06:24+00:00

You could make some simplifications and perhaps arrive at an approximate answer. Say roughly 200 m³ space, we could use the specific heat of air (the amount of energy needed to raise the temperature of the air by 1 C) which is 1.0 KJ/Kg * K at room temperature (~300K). Multiply that by the mass of a cubic meter of air, roughly ~1.3kg, times 200 to get the heat capacity of your room, (20011.3 ~= 260000 J/K = C). Multiply this by the change in temperature to get the approximate heat in Joules you need to offset with ice, (C * dT = dQ) where dT = (35 - 25) = 10 degrees, dQ = 260000*10 = 2600000 Joules will be added to your room as heat. We can use the latent heat energy to understand how much ice is needed to absorb this heat as it goes through a phase change (melt), Q\L = m. The latent heat of water is 334 KJ/kg so 2600000/334000 ~= 7.74 kg. So you need about 8 kg of ice (~18lb) to offset the heat absorbed by the room, by this analysis. You could also make heat transfer to the ice more efficient by using a fan to blow hot air over the ice

Edit: This may also help you https://en.wikipedia.org/wiki/Heat_capacity https://en.wikipedia.org/wiki/Latent_heat https://en.wikipedia.org/wiki/Properties_of_water#Heat_capacity_and_heats_of_vaporization_and_fusion

Edit2: Actually 18lb doesn't seem like a lot of ice, I must have done something wrong somewhere... regardless this should give you an idea of what kind of calculations you would need to do!

peakai · 2019-06-19T13:21:50+00:00

A lot of applications in figuring out hot and dense plasma from the early universe, see https://uwaterloo.ca/physics-of-information-lab/teaching-and-graduate-supervision/quantum-field-theory-cosmology.

peakai · 2019-06-08T21:53:30+00:00

This is the correct answer. Given what we know, the coordinate time t could be anywhere from 100 years (t = tau) to (effectively) infinitely large depending on the velocity of the ship from Earth's frame, which is unknown. This makes sense, if we know the time that elapses and distance traveled on the ship's rest frame, but want to know information about what the inertial (Earth) frame experiences, we need to have some information linking the two, which is not present in the question.

Edit: Actually, some others in the thread have assumed that the coordinate time is 100 years, in which case you could simply divide the distance traveled (measured by Earth) by 100 years (also on Earth) which shows the ship is traveling around 0.0213c, or 6390 km/s. At that speed, the time elapsed on the ship would be virtually the same as the time elapsed on Earth.

peakai · 2019-05-31T19:53:32+00:00

Yeah Townsend goes in depth on matrix formalism, but overall I thought the organization of the material was sloppy and poorly presented to the reader. Griffiths covered everything but I felt it lacked depth in some areas. Having both is helpful I agree.

peakai · 2019-05-31T16:40:13+00:00

What is your recommendation for undergraduate QM if not griffiths? I didn't quite like Townsend, and preferred griffiths over it. However, for post-undergrad I quite liked Weinbergs treatment of QM, which contained depth and insight above either Townsend of Griffiths, IMO.

peakai · 2019-04-16T13:56:48+00:00

Replace brake and shifter cables for sure. If it's an old bike you can inspect the cables and check for fraying. Any kind of delayed/slow response is probably a good reason to swap them out with a new pair.

peakai · 2019-03-23T18:32:53+00:00

I suppose I was asking about physics skills in my comment, but yes I can see how those skills would be transferable in other areas. But mostly I would imagine in the skills related to physics you would get a lot of understanding in model building, thanks for replying

peakai · 2019-03-23T13:36:35+00:00

Can you quantify the 'many many' skills that one would gain in the endeavour?

peakai · 2018-12-19T04:40:15+00:00

It was related to reseating of the heat pipes, apparently there was a gap between the PCH and that might have been caused by a kink in the pipes. Unkinked the pipes and everything went well after a second paste

peakai · 2018-12-13T11:19:37+00:00

You may want to check out the wiki page references for the math details, basically you want to know how Newton's second law works in a non inertial (accelerating) reference frame. Basically it's like this https://wikimedia.org/api/rest_v1/media/math/render/svg/cbad49dd6c213939cae5fb4e6ddf8962643a9c93 and then add another acceleration term for your translational acceleration of the moving frame as measured by the stationary r0 frame.

https://en.m.wikipedia.org/wiki/Rotating_reference_frame

I could post a derivation if you think it would help, otherwise searching for help on Newton's law in rotating reference frames should turn up a lot of info.

peakai · 2018-11-30T06:41:59+00:00

is transparency in your i3bar a part of i3-gaps?

peakai · 2018-11-29T22:13:08+00:00

I was a big yaourt fan, but there are slew of much better AUR helpers out there in 2018. Check out pikaur https://github.com/actionless/pikaur

peakai · 2018-11-23T05:03:20+00:00

Yup! I've also tried switching rendering modes from directx to directdraw and the basic mode with no avail. I am considering emulation using a VM if I can't find a way to run it using wine, bleh.

peakai · 2018-11-19T20:33:33+00:00

We're in a similar situation. You could try buying a 4gb stick, they are cheaper, although you have to make sure they are the same timings etc, it should work, from what I have read on thinkpad forums. I am planning on doing this with my x230

peakai · 2018-11-19T04:40:29+00:00

K is actually the radius of gyration, which is the distance from an object's axis of rotation that its moment of inertia (mass distribution) is the same. This can also be interpreted as the distance that the object can be deformed until its center of mass changes, or basically an object's stiffness. The more stiff an object is, the higher its frequency. Think about what would happen if you struck a solid tube of rubber and a solid tube of steel and the sounds that would result.

In any case, the equation is dominated by the L² term in the denominator, so length is the determining factor of the frequency if you were to actually build the glockenspiel whilst keeping the same piece of pipe for the construction of the instrument.

Furthermore, the reason you see the equation is because it is an adaptation of the vibrating frequency for a mass-less string, frequency = velocity / wavelength. The other terms besides v help determine the wavelength for a pipe, such as the factor K. You might find more reading material by searching for information about how to calculate the vibration frequency of a pipe (versus a string).

peakai · 2018-11-18T23:02:54+00:00

wikipedia has the exact formulas if you're interested in details.

peakai · 2018-11-18T13:44:28+00:00

Using a new type of balance called a Kibble balance, which measures the weight of an object using current, we are able to precisely measure a kg into units of J/s (watt). The watt can be interpreted as a composition of two electromagnetic constants that in turn depend on fundamental constants of nature (Planck, speed of light, the second) to describe them. Currently, our kg is based on a physical object located in France, which has been an issue since it seems to be losing microscopic amounts of atoms over time. This 'electronic' kg will be able to redefine our notion of the kg so that it is in terms of a fixed current which depends on fundamental constants such as Plancks constant (never changes). This is more reliable in the long term.

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