What the HECK are Planck Units?
100 Comments


Hey there Crazies. In our video about the universe being a big
simulation, we said this. What about Planck time? and John… John He was wondering what the heck Planck units were. First things first. What are units?! Units are really important! We can sit and theorize all day but,
eventually, we’re going to have to take some measurements in the real world. and that demands a unit! Which could really be anything as we saw in
the faking gravity video: It’s about 5 football fields, or 3 and a half Giza pyramids, or 110 Volkswagen Jettas, or 733 tube socks! It doesn’t matter what the unit is,
just that we all agree and understand what it is. Otherwise, you end up with a Mars Polar Lander
crashing into Mars because someone didn’t do a unit conversion. Seriously, links in the doobly-doo. Actually, it matters a little. The metric system is based on 10’s which is significantly easier to use than the imperial
system used in the United States. [Groaning Noises] So here’s the problem. What if you wanted to communicate the average
height of a human being to an alien race? [Alien Noises]
Yes, Milton, like you. They’re not going to understand football
fields or tube socks or any abstract units like miles or meters. You need something you know that they are
familiar with. We call these types of units “natural units”
because they’re based on nature. They’re supposed to be independent of our
subjectivity. You know, that stuff we impose on almost everything. For example, I could measure my height
in ground-state hydrogen atoms. All of which are identically about 1/10 of
a nano-meter tall. We sometimes call that an Angstrom after the
Swedish physicist. That would make me about 18 billion hydrogen
atoms tall. That’s pretty average for a human. This is kind of what Planck Units are, but
instead of being based on ideas like atoms, they’re based on the fundamental constants
of nature. The gravitational constant, which dictates
the influence of gravity. Planck’s constant, which determines how
lumpy and uncertain the quantum world is. The Speed of Light, which is how quickly different
parts of space-time can communicate. Coulomb’s constant, which governs electricity. And Boltzmann’s constant, which controls
the statistical behavior of large systems of particles. We’re pretty sure they’re the same everyone
in the universe. But, again, aliens are going to have
their own units and, if they have a different number of these,
they’re not going to use base-10 math either. To make these more universal, we need to do
something crazy. Just for the sake of argument, let’s set
all of these equal to one. The number one exists in all base-systems
and there are no more units. Wait ,how can you just do that? Well, you can’t, unless you change everything
else too. Changing those constants to one, changes what
units we use for: Length, Time, Mass, Charge, Temperature,
and, frankly, any other units based on those. Area, Volume, Force, Energy, Power, Momentum,
Frequency The list goes on! Every single one of those is now measured
in what we call a “Planck Unit” named for the German physicist Max Karl Ernst
Ludwig Planck, or just Max Planck for short, who invented
most of them back in 1900 CE. Historically, understanding physical quantities
starts with length, so it was very natural for Planck to do the
same with his units. Plank Length is about 10 to the negative 35th meters. To understand how small this is, we need
to turn back the clock a little. To the time machine! Playing the expanding universe in reverse,
we can look way back in time. At one point, the universe was the size of
a basketball, and then a human egg cell, and then an atom,
and then a proton. At 10 to the negative 18 meters, we reach
the smallest distance we’ve ever measured. Planck length is 17 more decimal places! It’s insane! When the universe was this small, we call
that the Planck Era. It was one Planck length across,
one Planck time old, and one Planck temperature hot, which is really hot! OK, let’s get back to the lab! What’s so special about Planck length? Nothing really. At least, not yet. Some models of quantum gravity say that Planck
length is the smallest possible distance. Because quantum mechanics loves it when things
are quantized like that. But remember, we’ve only been able to measure
down to 10 to the negative 18 meters, so we’re not really sure about anything
smaller. And no model of quantum gravity has experimental
evidence anyway. Even if space has a smallest amount of chunk
or whatever. It could just as easily be a 10th of the Planck
length or 1000 times the Plank length, as long as it’s less than 10 to the negative
18 meters. What I find interesting is how ordinary some
of the other Planck units are. Planck Mass is about the mass of a flea egg. Planck Energy is about what we could get out
of a 16 gallon tank of gasoline. Planck Resistance is about 30 ohms, which
is resistor I use all the time. That’s kinda cool. So, do you think the Planck units have any
physical significance? Let’s continue this conversation in the
comments. Thanks for liking and sharing this video. Please subscribe if you’d like
to see more science like this. And until next time, remember, it’s OK to
be a little crazy. In the last video a clone fell into a black
hole. Comment response time! Amit Patel was wondering why larger black
holes don’t spaghettify you like smaller ones do. An event horizon is an event horizon, right?! Yes, an event horizon is always a place of
infinite time dilation and yes, bigger black holes have stronger
gravity, but that’s okay because the strength of
gravity isn’t what rips you apart. It’s the difference in strength between,
say, your head and your feet. Those differences are bigger around smaller
black holes even though, overall, those holes are weaker. Kamikaze Katorin and DavidCH12345 asked what
the rest of the universe would look like to the expendable clone as he fell into the black
hole. At first, I thought maybe the entire future
of the universe would pass before his eyes, but that’s not actually the case. Even though the rest of the universe does
speed up from his point of view, it doesn’t speed up enough for him to see
the end of the universe. The last light he sees is not the last light
that arrives at the horizon. Infinity is so weird! Johan was thinking maybe the event horizon
and the singularity are equivalent. Mathematically, that’s not that far off. A singularity is just a place where an equation
blows up to infinity. The black hole singularity is what you’d
call a physical singularity. It’s there no matter what your point of
view is. The event horizon is what you’d call
a coordinate singularity. It’s there in one set of coordinates,
like the ones I’d use on my space station watching at a safe distance,
but not another set of coordinates, like the ones my clone would use as he’s falling into the black hole. So they’re very similar mathematically, but physically
they are very different things. If you’re looking for a more thorough conversation
about how Hawking Radiation might affect the fall into the black hole,
the comment thread started by david21686 is a good place to start. Otherwise, you’ll have to wait until I’m
ready to do a video on the Black Hole Information Paradox. It’s tough stuff, so it’s taking a while. And, finally, Your Master seems to want to start a clone union to protect all my clones from all the science we do here. That’s no fun! I’m not entirely sure how I feel about this,
but good luck getting them to organize. I have a hard enough time and they’re my
clones. Anyway, as usual, links to all the comments in the doobly-doo and thanks for watching!

100 thoughts on “What the HECK are Planck Units?

  1. Could you do comments about this article, which claim that Planck's Law was violated at nanoscale. Thanks http://www.nature.com/articles/s41586-018-0480-9#ref-CR4

  2. The pedantic clone is wrong once again. The metric system wouldn't be significantly easier to an alien race with 12 digits. Or if you used your knuckles to count. 12" to a foot would be significantly easier.

  3. Extend your planck period, and narrow it back before 1/2 planck time passes and boom… you just traveled to the past. Congratulations. You will understand this and thank me later.

  4. Holy shit… I've never seen this channel before… it's fucking terrible. How the hell do you have over 100k subscribers? Is this channel for like… autistic children? I'm being serious. Is this a kid's channel?

  5. So if the plank unit are based on plank constant and we even don't know for sure that if it's the smallest! Then what is the use of this all? Maybe aliens found an even smaller length and they used it as our reference to plank units! Wouldn't that we a problem? We Tell them something they interpret it something else!

  6. I don't think we'll ever go to an insane measurement system, no one can visualize a Planck length so it will still be something arbitrary, the same as any other measure, but at least we can relate to a foot or meter. For use with E.T. communications might be something starting with a progression of counts from 1 – 10, like ( | = 1 : || = 2 : ||| = 3 : |||| = 4 ) would lead to a faster understanding then trying to communicate the Plank length in a system they don't understand. Heck even to us Earthlings Planks length is just an abstract measurement only a tiny of a fraction of people know and likely no one can really grasp how small it is in any practical terms.

    It would also greatly depend on how we were communicating, obviously in person would greatly ease establishing communications. Anything radio will mean deciphering information, even if they knew the signal was not random it would still be pretty challenging to communicate, you would still have to build up from a very simple base, describing atoms is probably not the first goal.

  7. Great vid. What is the Planck unit for brightness though? What is the conversion from “SI brightness unit” to “Planck brightness unit”?

  8. I think you should've mentioned how he came to the planck length on accident to solve the black body radiation problem but otherwise all gold. it's also nice to mention things like colors would be different like the sun wouldn't be yellow if the plank length were different.

  9. I disagree with pedantic clone actually. The metric system is no easier than the imperial system at unit conversion; the prefixes are just multipliers. They don’t make distinct units.
    We could easily measure in millifeet or kilopounds.

    I weigh 0.25 kilopounds.

    Jesus I need to lose weight.

  10. Not to mention the Mars Climate Orbiter using the wrong units. The importance of having these constants is communication and having a unbiased frame of reference.

  11. The entire universe the size of an atom or a planck length? 😂 never heard of a more laughable theory. Absolutely ridiculous. I can’t believe Big Bang is still so widely accepted.

  12. The Planck Length is not necessarily the smallest possible distance that can exist. It's the smallest possible distance that can be theoretically measured. You try to constrain anything to a smaller accuracy and you end up with such a wildly undefined momentum that the range of uncertainty regarding that momentum overlaps the speed of light, which is of course not possible.

  13. Whenever N.L. have dispute imho it’s Nerd Clone who’s finally right. Nerd Clone doesn’t say that much but if he says something you can be quite sure that it’s right and spot on.

  14. I'm obsessed with the notion that a 20 equalateral triangle Geodesic sphere of ANY size is the key reference frame for measuring space and time. The ratio between the points of the 20 triangles and the perfect sphere that they define never changes no matter how large or small the sphere becomes. It seems to me that a clearer understanding of the relativity between space and time would be clarified, including a possible path to free energy. In my opinion, the game of golf obviously involves effortless power and so does our universe.

  15. ‘how many planck lengths do we move with one step?’

    ‘Over 9000 Septillions of plancks.’
    (only real DB fans will realize what i did here.)

  16. If something goes one unit forward. Then one unit to the left. Then one unit back toward it's point of origin. The difference between it's final location and it's initial location will always be less than the unit in question. So if there really is a smallest unit of measurement wouldn't that suggest that at the smallest scale things can only move in six directions? Forward, Backward, Left, Right, Up and Down.

  17. 2:30 – I literally got hopping mad one time when I was having a discussion with friends who insisted I couldn't set the value of C to 1. I was like, "Yes, I can! C is equal to one lightyear per year! I can do that!"

  18. Thank you for sharing your wisdom to me and the world. Aliens know what are inches feet and miles they know more about our math then us they've been coming to Earth before Jesus. I always talk to them.🌎👽🌌

  19. the reaction to nerd clone is every american hit with any metric system info. whoever decided imperial system was the way to go was the OG hipster

  20. The Planck speed has physical significance. G and h have physical significance. Planck length and time may have? They are SO small.

    Some people cite the HUGE number for Planck energy density as a potential energy source. This is taking the physical significance of Planck units too far.

    Which means we have to question the physical significance of Planck length and Planck time too. Are there other physical constants on which units could be based? Is the choice of G, c, and h arbitrary?

  21. A human is 18 billion hydrogen atoms tall? That can't possibly be correct. There are 7 x 10^27 atoms in an average human.

  22. How can plank mass be grater than the mass of the electron 😱😱😱😱😱😱😵😵😵😵😵😵

  23. The best companion to pbs space time. It defenitley helps to understand the complexity of our insane universe

  24. There is a paper published in 1964 showing that Planck length is the smallest measurable length. This is because it is the sizes at which focusing enough energy in such a small area would create a black hole.
    https://doi.org/10.1103/PhysRev.135.B849

    Planck time ends up being the smallest measurable period of time because of the speed of light is one Planck length per Planck time. Planck mass ends up being the amount of mass can we create a Planck length black hole. As a result, if there is a fundamental minimum length and minimum time unit it is most likely Planck length in Planck time.

  25. Whether Planck units have physical significance is how I found this video. I was trying to get an answer to that question myself. More specifically, I'm curious about Planck time. From what I've been reading, some people think time can't be divided any farther than 10^-43 seconds, or that any length of time shorter than that is meaningless. Other people seem to think it's just that our known laws of physics break down at that point, and any duration shorter than that is governed by some yet undiscovered physics, which would suggest that 10^-43 seconds may NOT be the shortest possible length of time. I don't know what to think, and I was hoping you could help.

  26. It doesn't matter how many fingers the aliens has as long as they have an equal amount on both hands and then just use that number for bases instead of the 10 we use. Same logic as metric, binary, octa and hexadecimals…
    I can hardly imagine the feeling of having been taught one system, day in and day out, that makes little to no sense for a majority of its students. And then learning everybody else uses another system which takes less than an hour (as an adult) to understand.

  27. Smallest unit implies something measurable, I.e. some separation.
    Irrespective of dimensions, two separated entities can yield, a line in any orientation, a circle having radius of the separation distance or a sphere. With circle and line we get properties like, slope, area, circumference.
    Most of these properties are dependent on actual value of separation.
    pi however is independent of unit of separation. So pi can be universal unit. It's a constant, but things could be say 4pi units or 5pi units etc.

    Edit: Possibility of radical change:
    In pure maths we have 5 singularities, 0, 1, -1, -infinity and +infinity. This can lead to ambiguity. One singularity is manageable.
    All math operations can be designed around pi, and pi as singularity.
    This could be possible because value of pi goes to infinity.
    For other all numbers, for operation results to make sense, pi can be used as energy of operation. Thus, pi can be kind of operator too. Ideally, in pure maths, operation should need energy which should be specified by definition of operators like +, – , /, ×. Also, value of operands and their order can influence operator. Pure maths should also cater to time required for math operation.
    Also, may be pi can be treated as 1 as well as infinity; and -pi can be treated as -1 as well as -infinity. 0 = pi – pi.
    e can be singularity too.
    Math can be designed around both pi and e, as singularities.
    e can be used for time required for math operation.
    Relation between pi and e can be used to generate number system.
    Because, in traditional maths,
    2 = 1 + 1 , and in pure maths, + needs to cater to energy of operation, time for operation, value of operands and order of operands.

  28. Thank you that picture helped me put my final touches to my own dumb theory about our universe and how we were created. Everything has to do with perspective. Having to do with our universe and what we call the infinitely small quantum realm. My original thought was we could be a rip or a hole made from the quantum infinitely small realm which spewed out our big bang after some kind of interaction. To us the quantum world and world of plancks and even smaller is infinitely small from our perspective but from looking at it another perspective it is the infinitely infinite. And we can be seen as the infinitely small within it. I see it as every little spec that interacts and collides from that quantum world of foamy like Wavey like or whatever it is really like then creates another universe within itself. We see our universe as getting larger from the big bang from the infinitely small collision or whatever but I think we were created inward from that infinitely small realm. Again it's about perspective. to us it is our universe getting larger but to that realm we've been created inward within it. And so we are even what that realm is made of itself as well. A bunch of universes being created with each interaction within itself. Now we are looking inward to the small scale as if it's what we are made of which we are but little do we know we are actually what it is made of as well. Most important thing is perspective. Of course this just me think Tanking here which I have fun doing so this is all in good fun for me doing this nonsense:)

  29. If distances change based on how fast you are travelling, and change the most significantly the closer you approach the speed of light relative to your original reference frame, wouldn't there be a speed you could travel at that would make a Planck length in one reference frame appear to be a metre, or a kilometre, etc., or even a light year, in the other reference frame?

  30. Just curious.
    What do you think of a “metric” system based off of Planck measurements, potentially unifying our understanding of integrated space/time units.
    Could we describe space and time units that fit together? like a gigaplanck in space equals a gigaplanck in time or something.
    Just an idea I’ve been batting around. Could it be feasible?
    I just figure a Planck unit is as universal as we could get….

  31. Wow very good explanation. You make some of the quantum mechanics terms so easy to understand.
    BTW i am 25 billion hydrogen atoms tall.

  32. I still cant believe your not bigger like Veritasium size but I do like the local community feel I get when watching you videos. I hope you grow to as big as you please.

  33. Hold on, but how do you determine the exact height… ugh… diameter of a hydrogen atom? Aren't the subatomic particles, that comprise it, point-like objects with a heightened electromagnetic field around them, which drops off with distance? How do you decide when the particle stops? It doesn't even have a surface.

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