The Planck Density: The Density of the Early Universe

I’ve looked at quite a few of the Planck base units, and I’ve even worked them out mathematically, but today I’m going to look at one of the derived units and I’ll compare it to some other things to see how big or small this is. Today then I’m going to be looking at the Planck Density. Let’s find out more.
Before we start, we need to know what density is. Density is a measure of how tightly packed a material is. In other words, how much stuff is packed into a certain volume of space.

To work out density then we need a formula, and units. To work out density we use the following formula, density and that is denoted by the greek letter rho equals mass divided by volume. The SI unit of density is kilograms per metre cubed. So now that we know what density is and we have our units, time to see how dense different materials are and then compare that to the Planck density, which is very dense indeed. At the end I’ll show you where the numbers come from. We’ll start off by looking at some very un dense things and work our way up.

Video where I derive the Planck units mathematically

Chapters
0:00 Introduction
0:15 What is Density?
1:30 The Density of Space
3:05 Air Density
4:05 Saturn
4:45 Water
5:23 The Planets
7:18 Metals
9:07 Stellar Objects
13:40 The Planck Density

[seanspartan]

Some theorize that the Planck density is a hard limit for blackhole singularities and they may rebound once the Planck density is reached. We haven't observed any yet due to time dilation around the blackhole.

[francoislacombe]

Fun fact. Silver was used to make electrical cables for the Manhattan Project during WWII. They needed to make large electromagnets for one of the processes separating the uranium isotopes, but they couldn't risk calling attention to the project by diverting large amounts of copper away from the war effort, so they asked the Federal reserve to lend them a few tons of silver from which they made the required electrical coils. The silver was later returned to the reserve, minus a small quantity lost during the fabrication process.

[robinannaniaz]

Most underrated channel on YouTube!

The intriguing topics and passion this person brings should give him millions of views and subs. YouTube algorithm and policies are completely broken!

[christianperegrine]

The US doesn't tend to use Imperial Units when we're talking about physics. Any physics class or text book, even at beginning/high school levels, will use the metric system. I'm American, and in my day-to-day life, I absolutely use feet over meters, but describing density in lbs/ft^3 is totally foreign to me. I would use kg/m^3 every time.

[GB-ezge]

Thank you. I finally proved to my wife that I am not the densest thing in the universe.

[senri]

I'm glad this channel got popular over time. Despite me not planning to pursue a job in the field, science and astronomy has (and still is) my absolute favorite subject in school. My teachers made the subject extremely fun for me, so I have respect towards any science teacher who is passionate about what they do. I'm so glad to have been in their classes.

I happen to be in my last year of highschool, and to be honest, I'm going to miss some of my science teachers. They all seem to take more care in making sure we learn about our universe, more than our grades.
Thank you for your videos. They're really informative and nice to watch, I often listen to them while working on a story I've been writing (or) homework if I ever get it, which is rare nowadays for me.

[jonnywilkin]

At a certain point quite early in the scales of the Plannk Density in this video (or the size of a human, up to the observable universe in your latest upload) it becomes too much for us mere mortals to comprehend. The example of the atom nucleus being the size of a tennis ball and the electrons orbiting around 3-4 miles away is useful to put size and scale into perspective. However, when it got to the sun's core having a density of 162 tons in a cubic metre, all comprehension was gone! Still the crazy numbers that followed this is fascinating and mind boggling, I appreciate your efforts to make it as understandable as you did! Thanks for the headache, I think my mind is close to Plannk Density right now 🤯

Looking forward to more content like this 👍🏻

[The_Robert.Fletcher]

I can go back nearly 70 years when our science teacher was trying to get us to come to grips with Density. I don't think he understood it. But he made up write out 200 times. "Density is mass per unit volume." Years later it is still clear in my head as it was when I put it there in the 1950s I am still befogged as before but I am going to play this video again.

[jlwilder]

CONGRATULATIONS on the 50K subscribers mark! 👏👏👏
I was one of the very first few to find your amazing channel and have been waiting to see these numbers finally happen for you!
It might've even been the Planck length video I saw when I was like, "man, as soon as people see how well this guy simplifies and explains these amazing things... BOOM!"
You cover these topics unlike any other and in a very unique and accessible way, too.
Thank you!
(And thank you for exploring the Quantum world as much as you do; it's so mysterious and invisible and you bring it to life nicely for your viewers: )

[bbbl]

It's surprising that you just did a video about the Planck density today, I was just discussing this with people a few weeks ago, believe it or not! I was discussing the theory that at the center of a black hole, the density isn't infinite, but actually the Planck density. Still incredibly small, but just not infinite. This also puts a link between the Big Bang and black holes, if the Big Bang started off at the Planck density, and the inside of a black hole is the Planck density, then the Big Bang and black holes may be related to each other. In other words, the universe we live in could be result of a black hole, or at least it's time-reversed counterpart, the white hole! We might be living in a time-reversed black hole!

Also, the Planck density provides an upper limit on Boson density. We normally consider Bosons to be limitless density in theory, you can have as many Bosons in the same time and space together as you want. However, it's Fermions have to be spread out from each other, having a maximum limit. The Planck density would provide the final limit for the Bosons too.

[TimpBizkit]

The planck mass is about 21 micrograms. This is about what a cube of water the size of a laptop pixel would weigh. It's not a large mass, but the planck volume is so monumentally tiny that the planck density ends up an enormous figure.

[jansenart]

Speaking as an American, who has worked in industry, density has never come up in common parlance or even when I was working in tech, though in college, I was using all metric for physics classes. It's therefore academic jargon, and in technology jobs, we have started progressing almost completely to metric. So, yeah we use kg/m^3 now. It's just:

• temperature (Fahrenheit for weather, cooking and body temp, Celsius for technology, like chemistry, GPU core or extruder temp)

• liquid volume (gallons, quarts, and fluid ounces, except for "fizzy drinks", which are in liters)

• weight (we use tons, pounds and ounces, Brits use stone, we don't know what that is, and metric in some industry and creeping into food. Influenced by "gram" and "kilo" being known quantities for drug culture.)

• velocity (miles per hour for cars, feet per second for firearms, knots for water and aircraft, m/s in tech and industry)

• distance (miles, feet, inches, industry uses meters.) and

• pressure (oddly enough: bar OR mmHg (yes, millimeters of mercury) for weather, torr for vacuum chambers, pounds per square inch (PSI) for everything else, never seen pascals used anywhere.)

...that we don't generally use metric.

Firearms, on the other hand, uses a composite and often competing system of:

• "caliber" (ratio of an inch of a given bullet or barrel bore land-to-land diameter, and in most cases we say "caliber" after a number to indicate that a dot goes before it and it has two digits. Exceptions include: ".357" which is just "three-fifty-seven", ".380" is "three-eighty" instead of "thirty-eight", which is ".38" and a different cartridge case length, and both are equal in diameter to 9mm. No matter what, "point" or "dot" is never spoken.)

• inches (for naval cannons and barrel length of any firearm, which may or may not include the chamber)

• mm (for firearms of certain non-American pedigrees, most small arms above 1 inch in bore diameter, and land-based cannons) and

• "gauge" (number of spheres of a given diameter of lead required to make a pound, for shotguns; this is a reciprocal length so, like photography f-stops, higher gauge is smaller diameter)

Send help.

[bobbyt]

If I would’ve had this curiosity and easy access to this info in school, I think I would have taken a different route in life!

[OverHeed]

Love this guy’s channel great videos, no clickbait, straight up to the point, as well as illustrating it clearly for peabrains like me who barely understand anything

[tomc.]

11:52 - 12:00 That is such a cool visualization of the nucleus!
I only recently learned that protons and neutrons also exist in a cloud (the way electrons do; they are after all also defined by a wavefunction) and have energy states that they transition between -- and that "nucleus soup" visual really drove it home. They aren't static. They aren't classical.

[simotsns]

Thank you again for these kinds of videos, having this in-depthness and still maintaining easy-to-understandness is hard to find elsewhere, kudos

[jacksonstarky]

The Planck density does an excellent job of demonstrating how the pre-Big-Bang universe may have been... and this video does as good a job as possible of visualizing such massive numbers for our limited human brains. I've been wondering about the connection between the Planck mass, volume, and temperature since your calculation video last month. Thank you!

[bholdr----]

@7:50- when it was mentioned that Silver is a better conductor than copper (I think it is the best conductor among (relatively) common elements), I was reminded of this story:

During WW2, copper was in very high demand, and the various War industries had to compete for enough for their products, be they electronics, wires, etc...

The US gov obviously couldn't just use silver instead, since it was both far more expensive, and was a valuable store of reserve wealth.

However, the Manhattan Project needed a HUGE amount of good conductors (for Oak Ridge Uranium enrichment, and, since the silver wouldn't leave US soil, General Groves convinced the US Treasury Dept. to release thousands of tons of silver for use there...

BUT, when they requested the use of some of the silver reserve, in tons of silver, the arrogant Treasury told them: 'Tons? How much... here measure silver in Troy Ounces.'


Oak Ridge got the silver, enriched the uranium, and built the bomb. And the Treasury got its silver back after the war... Wow, eh? (How cool would it have been to be a fly on the wall for those interactions!?

Cheers!

[mjpottertx]

Saturn has a density lower than water. That means if you find a bathtub big enough, Saturn would float in it. But unfortunately it would leave a ring.

[lancerall]

2024 update!: Scientists have now confirmed that the only object more dense than the Planck density is Kevin from 8th grade.