/sci/ - Science & Math

How do I shot web?

A train is accelerating at rate V...

Are the laws different in atomic scale to the cosmologiacl scare, or in the essence they are the same?

No real physics questions?

Do I have to invent the universe to make an apple pie?

>>1244386

Ooh dat hard question lol

What would happen if the strong nuclear force just 'stopped working'?

>Do I have to invent the universe to make an apple pie?

Only if you want to make it from scratch

The toilet in 4th floor section 3 unblocked yet?

What are your interests in research, if you had a trillion dollar grant what would you dedicate your life to study?

How much energy does an electron emit via radiation as it falls 1 meter?

Ask me stuff, /sci/.

self bump

>>1244386
Well they should be the same. Most large scale phenomina should be derived from small scale shit. This actually works for most things but not all. The problems is we are still missing alot of small scale physics. So we cant derive all the large scale shit.

We end up with an incomplete picture of the universe. Hopefully one day we will be able to fix this.

>>1244420
What force is acting on it?

Da fuck is the weak nuclear force?

I look it up, and it says its what causes atoms and shiz to radioactive decay. I thought decay was caused by quantum tunneling and was due to the uncertainty principle, not a force?

>>1244407
Atom nuclei would not be stable and explode because of how close protons are together.

Just letting you guys know that I'm using a tripcode today because some faggots are impersonating me.

>>1244475
As of now that is. :P

>>1244442
Ok, the weak nuclear force is the force that allows for quark flavor to change, an up quark may become a down quark. It also, allows for neutrino creation, and lepton creation. The action "force" particles are the W and Z bosons.
I could go on and on about it.

Do you have any particular question about the weak force?

>>1244443
OK, cool.

Suppose an extremely distant body was travelling toward our solar system at faster than light speed, would we be able to see it?

and

If tachyons (in this case, particles which always travel faster than light) exist, would we be able to detect them?

>>1244487
Oops... forgot my tripcode.

>Do you have any particular question about the weak force?

Force just doesnt seem an appropriate label. If it "allows" quarks to change and "allows" neutrinos to form, thats not really a force, a force causes shit, not allows shit.

>>1244442
>I thought decay was caused by quantum tunneling and was due to the uncertainty principle, not a force?

I dont understand, why would you think this.
I think you have the wrong Idea of "force". The weak force, isnt really to be thought of as a "force" like in classical mech. This kinda force is associated with a fundemental particle interaction. The particle weak particle interaction explains the decay.

>>1244499
The force is how they interact.

>>1244507
So how many midochlorians does an average proton have?

>>1244507
LOL, dude your a terrible physics guy. Keep trying though!

>>1244507
>>1244528
Neither of you are me. Stop it.

>The force is how they interact.

Gravity - all mass attracts
Electrostatic - Causes mass to repel when they get too close
Strong Nuclear - Holds protons and shiz together
Weak Nuclear - I still dont fucking know

>The weak force, isnt really to be thought of as a "force" like in classical mech.

So I'm right, its not a force

>>1244490
If something magically traveled faster then light, could we detect them? Yes, what makes you think we wouldnt we be able to detect them?

Could you explain virtual particles to me?

All I get from articles online is that "We can't see them, but we can see the effects they have on stuff", which doesn't help me at all. Do we know anything at all about why they occur? What they actually are?

>>1244545
>So I'm right, its not a force

Gravity is just the curvature of spacetime. Electromagnetism is just charged particles interacting with photons. etc etc. Classical forces don't actually make too much sense until you get to their microscopic description.

>sense until you get to their microscopic description.

I see youre right, But Im visualizing a force as something that effects the position of matter. So under that definition, I suppose the weak force might well be a force, but what bits of matter is it controlling?

How bout this, if the weak force disappeared, what would happen?

>>1244576
That wasn't me. Don't listen to him.

Excuse my oblivious-to-physics-type-question, but I couldn't find the answer anywhere:

To move forward an object needs to push another, right? Then how can a spaceship/shuttle ever propel itself, in the vacuum of space? Does it use only it's initial speed or is space just not that empty?

What in the fuck is the 'holographic universe' theory and what do its ideas imply?

>>1244545
The problem is the term "force". We actually dont use "force" in anything but very very baby physics (like first year shit). Most physics is calculated all in energy terms, and we dont use the silly flawed idea of force.

The 4 Fundemental forces, are actually 4 fundemental interactions. We identify these interactions, with common "forces" we see in more basic physics.

When you probably think of force, you imagine "imgainary" fields, that act at distance, like in EM. In actuallity, there is no "action at a distance", if you "see a force" it is because there are very small very fast particles interacting with eachother though space.

>Then how can a spaceship/shuttle ever propel itself, in the vacuum of space?

They carry a shit ton of fuel, explode it, the burnt fuel goes shooting out into space, pushing the rocket.

>>1244586
Current shuttles push burning fuel in the opposite direction. Newton's third law, nigra.

>>1244589
>gravitons

Sure, bro.

>When you probably think of force, you imagine "imgainary" fields, that act at distance, like in EM. In actuallity, there is no "action at a distance", if you "see a force" it is because there are very small very fast particles interacting with eachother though space.

That may be so, but i still dont know what the fuck the weak force does.

If you take it away, what happens?

>>1244589
That's what I said, faggot.

>>1244576
If the weak force dissapeared then a shit-ton of interactions wouldnt be allowed to take place. Interactions that are fundemental to the satability of matter as we know it.

All hell would basically break loose, most objects would collapse. The unierse as we know it would "break apart" into a sea of goo.

How do I calculate the torque and speed I need for an electric motor if I want to lift, say 3 pounds?

>>1244612
Depends on how powerful the electric motor is dumbass

>>1244612
Classical Mechanics, bro. How fast do you want to lift it?

>>1244617
That would be the torque...
>>1244620
The speed is not that relevant in my case...

>>1244605
Ok, look at the pic. The W is a weak force particle, anytime you see it, you say, ohh that is a weak interaction, or the weak force.

In the pic, the weak force is changing a neutron into a proton, it does so by changing a quark. It also creates a electron and a electron neutrino in the process. Does this help you?

I hope you other "Physics Guys" are keeping up. You really do flatter me, THANKS!

>>1244627
I guess I'll go with 1000rpm for the sake of it

>Ok, look at the pic. The W is a weak force particle, anytime you see it, you say, ohh that is a weak interaction, or the weak force.

So a similar thing would be to say, when an electron changes energy levels and emits a photon, it is the electrostatic force that is causing the photon to be emitted, so the weak for is similar in a sense, but works on different parts of the atom?

>>1244630

Could you please explain the copenhagen interpretation for me ?

>>1244612
Just use conservation of energy
Lifting => W=M*g*h

Your motor rotates with energy
K = I*w^2/2

As long as K >= W, then you will lift the object.
I is based off the mass and shape of the motor (rotational interia). w is the anguar speed.

>>1244673
>As long as K >= W
Holy fucking no, Physics Guy. What are you thinking?

>>1244673
Yeah, you dont actually need torgue to lift the object. Torque imples a force, whic imples your motor is accelerting.

If the motor is just at consant speed it can still lift the object.

Explain Schrodinger's cat in simple terms (very simple).

>>1244686
No to this too. The torque from the motor needs to be equal and opposite to what is applied by the mass if there is to be no acceleration.
Torque from the mass=mg*r where r is an extending arm from the motor (or the radius of a winding pully or something).

>>1244667
>>1244691

These two at the same time please.

>>1244680
Technically it would work. The Energy is spinning the wheel (motor) would be converted to lifting the weight. As long as it is greater, it will lift the weight for a time >0. Why would you think its wrong?

>>1244706
Because I doubt the goal was to store KE in a rotating body, then transfer it to PE of a object to be lifted. I think it was to have a motor perhaps wind up a cable around a pulley or something to lift the mass.

>>1244667
>>1244667
>>1244667
>>1244667
>>1244667
>>1244667
>>1244691
>>1244691
>>1244691
>>1244691
>>1244691

Is the force of gravity flipped with antimatter?

Like, do matter and antimatter repel?

>>1244734
No. Only charges are flipped. Mass is still attractive.

>>1244698
So many Physics Guys....lol....its funny.

The cat was used to explain that QM ideas can not be carried into the macroscopic world. It is a joke, not anything important. It just says that if QM was right macroscopically, then the cat in the box could be dead and alive at the same time. This is obviously false, hence it proves that QM shouldnt be used on a macroscopic level.


Copenhagen says,

1) The univserse is locally probablistic because of the Uncertainity principle between two non commuting observables.

2) there is a particle-wave duality

3) QM and Classical Mech obey a correspondence principle. Ie, I should be able to get Classical results by approximating QM results.

4) All information about a physical system can be obtained from a "wave function", which by itself has no real physical meaning


The Copenhagen is the standard way of thinking about QM.

>>1244716
Ohh, ic. Well, whatever, the Anon didnt say what it was for. Nor do I care about the application, Im not a faggot (engineer) after all.

>>1244758
You should have just told him that no motor is necessary to lift the mass, because eventually (by pure chance) enough air molecules will collide with the mass from underneath and enough will bounce away from above at the same time to cause a pressure differential and lift the object.

inb4 second law of thermodynamics
This event will happen after slightly less than an infinite amount of time.

>>1244796
Like in (infinity-17) seconds.

>>1244796
>>1244808
It's obvious you aint the real physics guy.
TRY AGAIN FAGGOTS (ENGINEERS)

>>1244587
Answer me faggots

>>1244630

THAT ANTI NEUTRINO IS GOING BACKWARDS IN TIME.

explain yourself science boy.

>>1245051
Yeah, thats what it does.
Why do you think this is a problem?

>>1245164

my problem is that going backwards in time would violate causation.
i'm pretty sure that doesn't happen.

>>1245051

The arrows don't indicate the direction they are going in, so the anti-neutrino isn't moving backwards.

The meaning of the arrows is pretty simple: arrows pointing forwards in time = it's normal matter, arrow pointing backwards = it's antimatter.

>>1245372

No, thats not a problem at all. Technically a particle traveling forwards in time is the same as an anti-particle traveling backwards in time. Mathematically it all works out in the end.

It just depends on how you want to think of it, like QM its open to interpretation. Both ways work and are equivalent.

yes. I know absolutely nothing about physics, will you explain it all to me so I can be smarter?

>>1245546
Nope, that would take too long. But if you have a small question, I may answer.

(Now guess why I've become a tripfag.)

>>1245572
Lol, yeah.....for some reason everyone wanted to be me today? I don't get it....I may consider that tripcode thing.

>>1245566
How about a basics course?

>>1245534

crazy stuff, but if they are equivalent why not draw a normal neutrino going forwards in time, that seems like the far more obvious option?

i suppose ill learn all this in the undergrad masters i'm starting next year, ill get back to revising my classical mechanics and entry-level field theory.

>>1244673
But where does torque fit into the equation?

What do you know about biophysics? I'm pondering whether I should major in it versus molecular genetics/microbiology.

If I go from a Maths BSc to a High Energy Physics or Quantum Fields Masters, would it be beneficial to do a postgraduate diploma to learn all of the "physics-y" stuff? I've been looking at a number of courses, and the UCL degree requires me to do one, whereas others (i.e. Imperial) don't.

>>1245722
I heard its a good field. I really dont have much experience with it though. I took a couple of medical physics courses before, but I dont think those are the same.

In any case, biophysics is one of the most growing physics fields, also pays very well.
Good Luck!

I wish I could help you, but I dont understand what you are saying. I am American (USA). I am not familar with the type of schooling structure you are talking about.

You said you did your BS in math, and want a MS in QFT or someshit. What do you mean by post-grad? Like you want to get another degree before you go into your Masters?

>>1245730
Going from a Math to a Physics masters shouldnt be that hard. I know a couple of people who have done this. You may have to study up alittle more then usually, for some undergrad concepts you missed, but besides that you dont need to take an extra degree or anything.

A postgraduate diploma is a course designed to act as a transition when doing a postgraduate degree you haven't necessarily had experience in. So it would be a year in between doing a BSc and a Masters, where I learn all the physics stuff I never learnt.

>>1245830
Ohh, ok. Yeah, if its only a year or so, then that sounds like a good idea. Although, in all honesty you probably dont need it. Most Math people can pick up physics relativly easy. A lot easier then the the other sciences or engineering at least.

Either way Im sure you will do fine. Good Luck.