P-planck time is the smallest amount of time

>P-planck time is the smallest amount of time
[citation needed]

Planck units are just a meme without physical significance.

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physics is gay anyway, lets derail this into biology

>he thinks biology is a science
If you didn't win at ISEF with a bio project before junior year why do you even try

thats the way to go my biofriend

reminder that both kurisu and ema work with biology and they are both cute

>biology isn't a science
Sorry that biology doesn't pander to your absurd and highly autistic """"physics"""" subfield. PS: All the useful physics is done by engineers, and you abuse the fuck out of math notation that it makes anyone's eyes bleed.

Agreed! It doesn't make sense that Veeky Forums anons bash bio when their waifus are biofags

>all the useful physics is done by engineers
Well if you know what a GPS is and how it works you'd instantly know this is bullshit

>abuse the fuck out of math notation
It's shorthand, we don't have to pander to plebs

also
>implying biology is anything beyond rote memorization
I've not met one biologist with any problem solving or critical thinking skills whatsoever

>I've not met one biologist with any problem solving or critical thinking skills whatsoever
That's because you're American. MSc in America is equivalent to German high school diploma.

Well, it is the smallest amount of time, that can be meaningfully desribed

Not even that

Planck units are just units derived from physical constants. Some are close to the smallest possible theoretical measurements but the concepts are not known to be meaningfully linked.

So in other words you have absolutely no valid reason to criticize Planck units?

There's no reason to criticise them outright, they make some particle physics calculations simpler.

However, there's currently no reason to think that they are the smallest anything.

I don't think user is criticising Planck units, just the way some people understand them.

think what you want, but

And what makes you think that?

I mean maybe that's right but I don't think anyone's found any evidence or theoretical justification for it.

The old Zeno meme needed an answer

Planck time is defined as the the time something needs to travel a planck length at the speed of light. Thats the justification.
If not, please tell me about the greater speeds and shorter distances there are

Planck units are an arbitrary bound which we choose to work relative to because it makes things easier.

It is not very different from any time you choose an arbitrary epsilon to work with in an analysis proof.

>Planck time is defined as the the time something needs to travel a planck length at the speed of light.
Yep

>Thats the justification.
Only if the Planck length is indeed the shortest possible distance, a statement for which there currently exists no justification. It's hella small but we don't know if it's the smallest.

Planck units are found from dimensional analysis, that's it. Planck saw that the physical quantity given by:

[eqn]\sqrt{\frac{\hbar G}{c^3}}[/eqn]

is a length and decided to use it to define a unit of length that was based off properties of free space, rather than arbitrary values chosen by humans.

It's much smaller than anything we're used to working with so we're not sure how stuff works at that scale but we haven't found anything that indicates that the value itself is significant in any way, that includes the idea that it's some kind of minimum distance.

Heck, if there is a shortest length maybe it's more than the Planck length, who knows?

Oh, so your real problem lies with the planck length I see.
But the planck length isnt really chosen arbitrary. Thats the whole point of it. Feel free to define a shorter distance. You could say "half a planck length", but that wouldnt be meaningfully defined

Haha muh lie algebras n shit

>But the planck length isnt really chosen arbitrary. Thats the whole point of it.
Exactly, Planck wanted a set of units free from human arbitrariness, but that's nothing to do with it being the shortest possible or "meaningful" distance.

Half a Planck length is just as meaningfully defined as a Planck length, it's:
[eqn]\frac{1}{2}\sqrt{\frac{\hbar G}{c^3}}[/eqn]

you called?

I'm just a popsci nigger but don't planck measurements play an important role in describing the largest possible "temperature" in the context of the speed of the light? Is there a relationship or am I getting things mixed up like a baka?

both of those dishes look way too fucking heavy for me.

and yeah I'm not really educated on the matter but I would guess that it could be used to define a max temperature

>just as meaningfully
not really. I mean you can define everything mathematically. I could say 3 x 10^-1309 m is the smallest distance and we could go on and infinetly top each other. Thats not the point.

>Thats not the point.
Then what is?

The only point of Planck units is to have units defined from fundamental constants, that's how they are defined. You seem to think that there's something more to it?

What I'm trying to get across is that the Planck length has no confirmed significance as a minimum length or anything. It only comes up in the various theories of quantum gravity and only as a general length scale rather than any important value.

Of course it is only theoretical.
Look up planck constant and the uncertainty principle

I know what those things are. They both have confirmed significance, unlike the Planck Length, which is just a bunch of significant things multiplied together.

Do you know where it comes from?

We have observed that particles move in quantum leaps, the size of Planck length

You can charge a particle as much as you want, it won't move -- if it does move, it will move Planck length

>We have observed that particles move in quantum leaps, the size of Planck length
>You can charge a particle as much as you want, it won't move -- if it does move, it will move Planck length
Gonna have to slap a big fucking [citation needed] on that claim. We can't measure distances anywhere close to the Planck length.

>Do you know where it comes from?
Yeah I've already explained this. Planck proposed a set of units free from human arbitrariness so he defined them using fundamental properties of the universe. The result was the Planck units.

>>P-planck time is the smallest amount of time
>[citation needed]
There's no strong reason to believe that any of those particular numbers represent a least observable quantity.

>Planck units are just a meme without physical significance.
You can look at them as follows:

The Schrödinger equation tells us how fast a quantum mechanical state oscillates. For an Eigenstate with energy E, it reads

[math] \dfrac {d} {d t} \psi = (-i) \dfrac{ E }{ \hbar } \psi [/math]

The rate of change of the state is determined by its eigen-frequency [math] \omega = \dfrac{ E }{ \hbar } [/math].

Consider now the Einstein equation, which tells us how spacetime is affected by matter

[math] G_{ \mu \nu } = 8 \pi \dfrac { G} { c^4} T_{ \mu \nu } [/math]

Here c is the speed of light, G is the gravitational constant, [math] T_{ \mu \nu } [/math] is the matter energy density tensor and [math] G_{ \mu \nu } [/math] is the Einstein tensor.
The effect of basic matter on spacetime curvature is not large, because [math] c^4 [/math] is big. In fact, [math] \dfrac { c^4} { G} = F_P [/math] is the Planck force of 10^40 Newton, and so things only get crazy when the pressure [math] T_{ \mu \nu } [/math] get accordingly high.

We can rephrase this: If g is the metric tensor, the primary quantity determining spacetime, the time component of [math] G_{ \mu \nu } [/math] expands as

[math] G_{00} = \dfrac { 1} {c^2 } \dfrac { d^2} {dt^2 } g [/math]

Now let [math] L [/math] by any characteristic length scale, [math] T [/math] the time that light needs to travel L, and consider the energy estimate [math] E = L^3 T_{00} [/math].

With the Planck length [math] l_P = \sqrt{ \dfrac { G \hbar }{ c^3 } } [/math], we may write 00 of the Einsten equation as

[math] \left( T \dfrac { d} {dt} \right) \dfrac { d} {dt} g = 8 \pi \left( \dfrac { l_P } { L } \right)^2 \dfrac { E} {\hbar } [/math]

So even if T is small, there is a quadratic comparison of the (energy along the) length to the Planck length.

youtube.com/watch?v=U6fI3brP8V4

>what's smaller than a planck unit?
>half a planck unit

>80 minute long video
>doesn't provide timestamp for the relevant part

put some effort in breh

Because I don't remember the exact point

But you should watch the whole lecture anyway

It's somewhere around 46:30

Plank length and plank time are simply the minimum size of position and time increment that can be meaningfully measured. In order to measure a particles position and momentum, we need it to interact with another particle (the measuring instrument). This by definition changes the measurement.

The best interpretation of plank length and time is the smallest margin of error that can exist when making very small measurements. It has nothing to do with the "smallest space a particle jumps when moving from point A to B".

The Quantum in QM refers to finite energy jumps of particles in bound systems (i.e. electrons in the potential well of a proton). I have never heard a legitimate theory/experiment that space and time are also quantized.

I've been watching for more than 10 minutes from your recommended point and Planck length hasn't come up once. Given the list of contents at the start it looks unlikely to ever come up.

I don't even need to watch it to know that this claim:
>We have observed that particles move in quantum leaps, the size of Planck length
is total bullshit.

>Plank length and plank time are simply the minimum size of position and time increment that can be meaningfully measured.
Heck I don't think there's even any evidence for that. I think some quantum gravity theories say that sort of thing but nothing verified.

>The Quantum in QM refers to finite energy jumps of particles in bound systems
Thank u

Who's ema?