> philo > space-mach-principle-acceleration-and-velocity-solved-by-special-relativity

Is Space a Thing?

It's Okay To Be Smart - 2017-06-20

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Since the days of Ancient Greece, philosophers and scientists have been wondering: What is space? Is the absence of things… a thing? These questions continued to fascinate physicists in the modern era, leading Isaac Newton, Ernst Mach, and Albert Einstein to wonder about the true nature of the fabric of the cosmos. The search for an answer led them to some of the greatest theories in physics. This week, we ask if space and time are really real, and how they come together to make “spacetime”!
“The Fabric of the Cosmos” by Brian Greene http://amzn.to/2tF9fZO (Public library: http://www.worldcat.org/oclc/681349969)
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It's Okay To Be Smart - 2017-06-20

Space? That's just, like, your perspective…

Tell us what you thought of this week's video!

Katrina Taylor - 2019-02-23

Brah. Space cannot be nothing because if their was really a vacuum them everything in the universe would be pulled together so tightly it would be a point. Einsteins determination about space time is absolutely correct, but only because the universe is filled with dark energy (which in a sense acts like anti gravity). Allowing things not to crash in on each other, the universe to expand, and yes for you to feel the spinning force.

Ger - - 2019-03-07

I’m just here for flat earther comments

Brandon Metcalf - 2019-04-09

its 2019 and im watching this and where do you do your research???

Cameron Tibbs - 2019-06-15

I need to stop watching science channels, my mind is destroying slot of adverts
Nice vid

Klm49 - 2020-02-06

I had long suspected that this channel was run by The Dude. Happy to have it confirmed!

Imię Nazwisko - 2017-06-20

But... What is a "thing"?

*music from Vsauce*

sogg damone - 2019-06-12

That can be sensed by any of our 5 perceptions. Is it nursery school class?

brian bullivant - 2019-09-30

"Thing" was the handy helper of the Addams Family.

Desi Thug - 2019-10-19

What's humor?

Sandra Monney - 2019-11-23


Reymart Bara - 2020-01-21

Thing anything that Has something

Kai Widman - 2017-06-20

I have never seen a 3D graph of space-time like that before. I like it.

Therapist Gus - 2019-01-26

Jack Müller ... just while I was enjoying the simplicity of the diagram 🤦🏻‍♂️ LoL

Rainlitnight - 2019-02-05

@Jack Müller this is a very late reply, but imagine taking twins and keeping one on earth and training one as an astronaut. Now imagine 5 years goes by, and the space twin comes home. They will have aged slower than the twin that stayed on earth due to the effect space time has on their body. Therefore the faster the spaceship goes, the slower the people inside will age. It's actually fascinating, does that help?

AcidMist - 2019-03-05

​@Jack Müller I think it's because you have to think about the direction the objects travel in. They always travel in a straight line. Let's take his example: Constant velocity means you are traveling at a set speed in a set direction. Since a direction has been set, it's a straight line. At rest means the you are not moving at all...so no velocity no acceleration... means you are moving through time in a straight line...relative to other moving objects. An accelerated object means it's moving..so it's not at rest....but wait, since it's accelerating that means it's changing direction...and this is where the speed of light comes in.

Let's assume you can reach 99% the speed of light. The faster you move through space, the slower you move through time...so you would always be moving up in spacetime until you hit 99%. As you can never reach the speed of light, that's your ceiling. Since you are no longer accelerating, you no longer have a curved trajectory. Now you go back to a straight line because you are moving at a constant speed (99% speed of light) in a constant direction (straight). This is the same if you decelerate, your direction is now down....which is curved.

I know I'm late but I'm blazed

Jack Müller - 2019-03-05

appreciate the explainations, i think i got it now.

Sanvi Jain - 2019-04-30


Codie Tanguma - 2017-06-20

But the real question is..
If crabs walk on the ocean floor, when they look up, do they see flying fish?

Nicole Tan - 2019-10-05

HA G0TT EEM ye there are flying fish

David Hennessy - 2019-10-09

So is an apple falling or sinking

HERMITA PURPURR - 2019-10-25

HA G0TT EEM ye but crabs don't know that

Devashish Sonawane - 2019-11-27

Paolo Vallejo So are Birds swimming in just a very less dense medium ?

Elbert Higgins - 2020-02-21

in Asia they see frying fish

V3M2 - 2017-06-21

Im having a hard time understanding this.

Johnnie Walker - 2019-12-31

You're not alone, rest assured. :D

prophetchannel - 2017-11-19

Albert Einstein was kind of a rockstar. I mean he was a celebrity scientist and he even had groupies lol.

Angelica - 2017-06-20

That Albert Einstein graphic is life

Z - 2018-02-14

It's from here https://youtu.be/BM2-FY2QEog but it's funnier because of how it's used in the video

Mer Fah - 2018-07-02

Everytime someone says Albert Einstein that graphic should pop up.

Just like the "THE POWERHOUSE OF THE CELL!!!! *thunders in background*"

jojolafrite90 - 2018-07-10


Sky Lord Panglot - 2018-07-27

But the question is "Is life a thing?"

Ashlin Joshy - 2019-02-07

@Rob Green red star by chris something

Sk Sury - 2017-08-07

1:03 "It all has to do with relativity"

slyyvl - 2017-06-21

Okay! I have a huge crush on Einstein now stop teasing me

Alpha Wolf - 2017-09-21

V. Erin each person is different?

RealKidZ Reviews - 2018-01-17


Timothy Morrison - 2019-11-05

🕸🕷 so did everyone female at that time

Uriah Siner - 2017-10-30

Why did that apple look so huge?

Jack Ahah - 2018-06-27

Can you change your gamer tag so it shows your balls

Elijah Thomas - 2018-06-29

Jack Ahah lmao 😂

JuJu Yee - 2018-12-22

Maybe bc it's a huge apple?

me Espin - 2019-02-13

It's only relatively huge, Joe the host is actually a dwarf

Ginny Jolly - 2019-09-02

It's a huge apple. You can find them commonly in US groceries. You can also find apples that are about half that size, called "lunchbox" size.

Kirk Lau - 2017-06-21

someone GOT TO MAKE that color changing Einstein graphic into animated GIF.. please!

Kazuya - 2017-06-20

I was following along until he started talking about spacetime

Noa Katz - 2018-11-24


60 Second Success - 2017-06-20

3:10 Bert Stein. Who's that? ( ͡° ͜ʖ ͡°)

Kobe Bryan Calayag - 2017-10-16

And 1:05

Ray - 2017-11-02

definitely not Bert Stern

Sky Lord Panglot - 2018-07-27

Do you think close friends called him Bert actually? Sounds plausible and strange.

CL Melonshark - 2018-09-11

Bert Is Tein?

Ankit Arya - 2019-08-20

@Kobe Bryan Calayag ert ein😂😂😂

The Centalist - 2017-06-20

What about dark matter?

Nycoz Nite ツ - 2018-03-26

The Centalist if u use the reality stone from marvel to convert matter to antimatter

I Banged My Head To Keyboard Gjggjnvn Tcnrtcftyv - 2018-05-06

It doesn't matter.

Carlosmp20 - 2018-06-14

Fred King
Scientists do know quite a bit about it.

European Colonist - 2018-07-14

The Centalist And what about anti matter?

BonifiedWingnut - 2018-12-13

Dark matter is a math equation that fills in the gaps for bad math and mixed up reference points and speed calculations to make the Universe fit the math...can't tell it's there but it makes 2+2 = 7 when you need it to.

sion8 - 2017-06-28

No! I wanted to see Einstein's awesome entrance!!!

(watches until the end)


tgg1217 - 2017-06-20

can we please have that Einstein gif?

Desi Thug - 2019-10-19

no you can't

Timothy Morrison - 2019-11-05


earnnathan Tagab - 2017-09-25

I was saying
through the entire video

Wonton - 2017-06-21

"Einstein said light could travel without a medium"

Wasn't that proved by Michelson & Morley?

Bruce Wayne - 2017-06-28

Didn't they say since the big bang, space has been growing at an accelerated rate? Doesn't it have to be a thing to grow? And if space is getting bigger, what is it growing into? What is the space that isn't space... yet?

Shardul Paranjape - 2018-05-02

Think of it this way -
if the world is a painting , the lines and paint are objects (matter and energy) and the canvas is Space.
And when all of these PBS videos state "space is expanding" it means the canvas is expanding.
There is nothing beyond the canvas, or rather it can't ever be known, because the laws of physics hold no meaning outside of spacetime.

P.S its intuitive to think that the observable universe is increasing or just the distance between things is increasing and that is the 'expansion' , but it is actually all of that plus the actual expansion of space.

wa ta to do - 2018-11-10

Good questions

Venkatesh Chakrabarty - 2019-01-01

@Raheel Arif Nope. Every point in space is receding away from another. Space is increasing.

Marley Janim - 2019-09-12

Think of the universe as a half inflated ballon...

squeeze 1/3 of the balloon

the other side is expanding

Into the expantion

This is how gravity work

1 - think of space as a fluid

The mass of the earth dispersed space....

Space compresses on earth...

That's how gravity works, it is a push

voidremoved - 2020-02-17

@Venkatesh Chakrabarty This is what they tell us... That every point is receding away from another. That's fine. Then they tell me that the milky way galaxy and another galaxy are going to collide some day. So how can they be receding from one another? All this science is stupider. They don't have a clue what they are talking about they just want grants?

Scott - 2017-06-21

Do "Is Time a Thing?" next!

Golden Kipi - 2017-06-20

that graph showing relation between space and time was helpful to understand spacetime, great work as usual

flow - 2017-06-21

yh.. very ncie

Riccardo Wright - 2018-07-16

But it doesn't make you understand what TIME is. Time is seen as a sort of space something can move, "flows" through.
Philosophically uninformed videos :/

Rusty Shackleford - 2019-09-08

@Riccardo Wright Universe doesn't have to make sense to humans. Humans couldn't fathom germs, now we do.
If you say you understand it fully, then you don't. Watch startalk.

We have tools to help humans try and grasp what is happening. Like maths for blackhole gravity. We humans have a need to make something this or that. Yet light is a wave and a particle point. It's not a wave OR a particle. We don't have the right definitions at this time to describe many things that math can prove. That is all. Our time of understanding/definitions are going to update as we gain a sensibility of it all. Humans couldn't fathom germs, now we do.

Riccardo Wright - 2019-09-08

@Rusty Shackleford it absolutely MUST make sense to humans. Not now, not tomorrow, but it must have to possibly to make sense, even if we will never understand it - in other words, we must be able to understand the universe completely, even if we will never practice succeed in it.

Riccardo Wright - 2019-09-08

@Rusty Shackleford the fact that we can't understand what maths proves it's a problem, but what does it mean? It means that there is a real shift between reality and the object of science itself. Reality as we experience it normally is not just an illusion, but it's the realm in which we can't not live. We don't live in the realm where things are and aren't at the same time - at the same time, to make sense of our reality, we must construct something that isn't part of normal reality. One of those things is time. We don't, and won't ever experience time for what it is according to scientific theory. But scientific time isn't TEMPORAL at all. So, while "time" may be a physical notion, the character of temporality is the foundamental way of human experience of reality.

Shadow Cat - 2017-07-14



SirMikeys - 2017-06-21

The real question is: Is consciousness a thing?

Fandom guy - 2017-11-06

It's information, and things are information.  So maybe?

sabi6684 - 2017-12-29

SirMikeys we’re not conscious enough to figure that one out yet..
Our conscious is within space, and space within our conscious...
i think...

Jonathan Ameh - 2017-06-20

this actually helped me finally understand spacetime .a concept I just couldn't get my head around but it makes so much sense. I'm saving this video💯

Jonathan Ameh - 2017-06-20

space isn't really a thing, just a part of a thing. space is 3 dimensions but we are 4 dimensional and the fourth dimension is time.
my theory is that the expansion of the universe (which is constantly accelerating) is time and it explains why time only goes in one direction because the universe is only expanding not contracting. Matter warps space time and this warping effect causes gravity however the warping effect also causes time dilation due to time being a quantity of space time. this also explains why the speed of light is constant as photons are massless and therefore do not warp space-time and can travel at the maximum speed allowed by space ( shown by that nifty graph at the end other the video). I probably just came to the same conclusions as many other people but this video really cleared it up for me. Thanks itsoktobesmart !

SAMURAI 武士 - 2017-06-24

This is totally underrated, well done!

Doctor WhoTuber - 2017-07-02

Why did you have to give us blue balls with the Albert Einstein thing? I was looking forward to that introduction.

Evy Hsen - 2019-10-20

god’s bath water
Me: dies of laughter

Crack-Fetch-Shock - 2017-06-21

this is like the dopest video, great job.

"-No, too late!" I lol'd :D

Gabri'el Alexander - 2017-07-01

This episode was so funny and so clever!!! (^_^)

Your channel has really come a long way and is now my main science channel... THANK YOU!

MangoTube - 2017-06-20

The real question is:

Is thing a space???

Jonathan Day - 2018-07-16

If you have two very accurate clocks near each other, they bend spacetime. This has been observed with the latest generation of atomic clocks. This can be interpreted as things having space as the extra spacetime comes from somewhere.

You could also argue gravity. Gravity warps space. That means a thing has created space that wasn't there before. Some don't like curvature of space, too bad. Light can only travel in straight lines, therefore space is not flat.

Since there is a maximum density for mass, energy and information, things need space. Inflation theory says that if the space doesn't exist and the density is high enough, the thing will create the extra space needed.

Conclusion: Things are a space.

NikTheFix - 2018-07-16

What is this maximum density of which you speak? Degenerate matter? or do you mean some kind of limit imposed by Plank granularity / quantization? I've not heard of a 'diminishing returns with compression' other than those we expect from the known physics. Could you elaborate - especially about the information density limit.

To say that light travels in straight lines could be misleading. Better to say that light follows a geodesic in space time.

Jonathan Day - 2018-07-16

This bound limits entropy and information, and thus mass and energy.

But you're also bound by Planck length and Planck time. You can't have a wavelength that is shorter than a Planck length, even in a black hole. It's arguable you can't have that as there's insufficient time for a full oscillation. I'm guessing four state transitions implies four Planck lengths for a full wave.


But if the energy density is sufficient for inflation, the rules change because that energy suddenly gets distributed over a much larger volume. The book "The First Three Minutes" describes this well.

NikTheFix - 2018-07-16

+Jonathan Day
But is not the Bekenstein Limit defined by the planck length? - 2 photons in such proximity being sufficient mass-energy to create the black hole. Frequency dependent too I guess.

What is the necessary mass-energy density for inflation to occur?

Vitalius 211 - 2018-07-23

Things are actually mostly empty vacuum due to most of an atom's atomic weight being held in the nucleus while the rest of it being empty with electrons whizzing around.
So....yes, mostly. And even then the particles that do make up atomic weight are existing in space itself, and are bound to the effects of spacetime and relativity.
Also this is why neutronium is so terrifyingly dense material - neutron star stuff - because it is composed of compressed atoms where the electrons are squashed down against the nucleus that they actually travel freely between the packed-in atoms.

...A serious answer to a joke question.

Nikhil Menda - 2017-06-20

HOly crap this is enlightening. the part at 6:21 blew me away. I never thought about spacetime like that before, Thanks Joe!

Leonardo Celente - 2017-06-21

"That's like your perspective, man" - Be Smart, The Dude

Nathan_Fellicia - 2019-03-30

space is...

that long bar on your laptop

Echo - 2018-06-29

0:55 "then you won't mind giving me some" lmfao

Tuchulu - 2017-06-20

What's the Einstein "theme"? It sounds totally wicked, bro

Bob The Sir - 2017-09-28


Albert Nave - 2018-01-26

BubblebuttBubberduck BEGONE THOT

Neurofied Yamato - 2018-10-15

Thank you! a very awesome music

Tom Trval - 2019-01-08

@Bob The Sir You are best

Marie Sabolová - 2019-08-27

When I saw that title: ,,So not
sleep tonight, I quess..."

Nav Explains - 2017-06-22

But won't the water be spinning relative to the bucket, or vice versa?
Not to say I don't think space is a thing, on the contrary, I just think that proof isn't the best one.

Izzy SoDope - 2019-08-24

I appreciate how this channel factors in the relatively short attention soan of people and constantly bombards us with changing images and graphics

The Musical Science Kitty - 2019-08-19

2:35 when you get spinned in the washing machine

Lady Violety - 2017-06-20


Malvolio Maximillian - 2018-02-05

LordHylar Badass rock music start playing

The Anti-Christ - 2018-06-21

1:22 Excuse me while I rebuild from ground zero as you have officially blown my mind

Vera Alvarado - 2019-05-12

Albert's "Soundtrack" is awesome :D I bet there's a power metal fan at the PBS staff haha

LordShkazn - 2017-06-20

When you're looking at the units for acceleration, and you realize that time is 2D.

abc def - 2017-12-23

"space is a thng" is new to me. space here means distance concept or material made of concept?

Aiman Naim - 2017-12-14

-The Space Core

llDarkFlowll - 2019-07-13

3:25 can you tell that the rest of the universe is moving faster than light when he spinning?

AS. I see The World - 2017-06-20

Try explaining that without using theories. 😂 smart enough to know when it becomes guess work.

Flip Godfrey - 2017-06-20

I'm gonna use this to win any argument I ever have....

"Oh yeah? Well, space ISNT a thing!!!"


GiggitySam Entz - 2017-08-27

Ohhh I was expecting a loud big guitar solo climax when it's finally Einstein's turn :'(

Adam Spears - 2018-05-19

Can anyone please clarify this?
I've heard that the universe started out from a point infinitely small; hot & dense.
My question is, if the starting point of the universe was just a hot & dense state...then what was available to compare its temperature & density too?

Hot compared to what?
Was there a temperature outside of this hot dense state?

Dense compared to what?
Was this hot & dense state contained inside of something else with less density?

How can something be described as hot & dense, when there is not yet anything else to compare its temperature & density to??

-Thank You in advance for your clarification.

roner61 - 2018-06-13

You need to check temperature definition:
Cold and hot are relative to atoms movment.
The coldest: atoms with no movment.(or minnimun possible)
The hottest: atoms moving at the maximun velocity possible.

Adam Spears - 2018-06-13

roner61 Thank You for your reply. & yes you are correct.
But let's remember that at the moment just before The Big Bang event happened, there were no atoms yet. The 1st atoms of Protium, which is just comprised of 3 quarks that make a proton, didn't form until after the singularity state.

So my questions remain, hot compared to what?
Dense compared to what?

Jason Anthony - 2019-02-25

I suggest you look into hawkings theorys of the universe

michaelrose93 - 2019-05-22

"what was available to compare its temperature & density too?" < Nothing, but then again, no one was around to make comparisons then. We're comparing it to the present moment.