I am in Calgary, and am incredibly relieved to know that whether one uses the Karman Line or the McDowell line as the demarcation of the space-earth boundary, I am at least three times closer to the warm, inviting expanse of space than I am to the desolate, inhospitable void that is Edmonton.

Nothing is near Adelaide. Can confirm.

I always find it amazing that looking at an object that is just 5 or 6 miles away has more air between you and it then between you and space.

4:20 Got me thinking "plz don't use inches, plz don't use inches!" Yess, lego bricks! Finally a superior unit of length!!!

Dr. Gray's comments on the value of spaceflight are incredible.

13:27 - I love the fact that the 3 towers of Lego are shown with increased gap between them as they rise higher up in the "space". The is round and the curvature is shown by that. Such detail. Love it.

Honestly I think I needed to hear Dr Gray's point at 11:50 today more than most other days, thanks doc

It is really disappointing that this channel is in such a decadence, in plain 2019! I sincerely think that this is the best channel KZfaq has ever granted, and this is something that we might not find again in some time... Such great and accurate content hardly can be found anywhere else! Having professors and great scientists like them spend their time explaining interesting subjects to the general public for a mere 60 or 70K views is just... Why are people wasting such magnificence! What is going on with the world?

I am blown away by dr. Grays almost superhuman ability to calculate vast distances into lego bricks. A true talent!!

"If you want a line, you might as well put it the middle of a region that is well bounded" - My new favourite quote! XD

I think that idea of closeness of space is less unbelievable for people who live at mountains than flatlanders. They know that walking 1 km on is easily done under 10 minutes, but going up 1 km is hard work and takes couple of hours.

Who else heard the signal from Contact?

Props for including a Canadian reference!

I've been following this channel since the beginning and it's been interesting to listen to Dr. Gray's accent change over time. I notice she sounds the most Canadian when she's pronouncing numbers and the most English when saying the names of places.

Oh wow Dr Gray is doing such a great job at delivering a strong message in a compelling way !

Humm...very impressed by Prof Gray's presentation skills, clear and concise!!

That last sentence is so incredibly important. Far too often, people look at things in black and white, and more often than not, I find there's never such straight-forward answers.

Love videos from Dr. Gray!

Had no idea how far away GPS satellites are - it's mind blowing to think that it takes a mere bunch of seconds for my phone to sync up with at least 3 of them!!

Love all the Star Wars droid sounds on those satellites.

Really wel presented -- appreciated Dr Gray

The joy when you see a new Sixty Symbols video is up :)

Really cool video! Love the scale and the 3D visualisations to give perspective!

That subtle bit of the sound from Contact. Very nice touch.

Fantastic video! But in the quest for clarifying definitions... ...those are clearly Lego plates and not bricks (for understandable reasons of scale)... :-)

excellent presentation. Thanks!

I can tell right now I'm going to end up linking this video in SO many online arguments!

Great visualizations. It's nice to actually see the scale of the numbers.

This video was awesome. Thanks for sharing :)

That's fascinating. When you put it that way then space is a lot closer than it seems or feels. Amazing. Just subscribed.

Ty for that info. I was curious about this exact thing.

Great episode. As always, Dr. Gray’s argument is enjoyable to watch. Thank you!

I think there's really two different questions to ask when defining this boundary between the atmosphere and outer space. One of them is how high up can you go and still reasonably say you're flying, not orbiting, and that's the Karman line, which sets the highest limit for what you might consider still being in the atmosphere, above which you are definitely in space. The other is how low can you go and still reasonably say you're orbiting, not flying, which is what this new paper tries to establish, which sets the lowest limit for what you might consider still being in space, below which you are definitely in the atmosphere. In between those bounds, whether you're flying or orbiting depends on your speed and shape: if you're moving fast enough that you'll stay up despite how un-aerodynamic your shape is, then you're orbiting, not flying; and if you're not moving that fast and can only stay up if your shape takes mechanical advantage of the atmosphere for lift, then you're flying, not orbiting.

It's refreshing to see this poetic yet rationale take on mathematical observations that include many real-world variables rather than just cold, hard semantics of the math in question which is still very impressive in it's own right.

This Alan Eustace skydive record is news to me. When Felix Baumgartner made his jump it was with worldwide coverage and a huge amount of fanfare. Where was the news coverage about the Eustace jump?

I find the definition of the Kármán line to super satisfying and also making a lot of sense.

Ah yes. A highly scientific school appropriate video about getting high.

Excellent, as always! Two comments. First, as an aircrew member, I saw the curvature of the Earth in a zoom climb that topped out at 60,000 feet. Second, that is the healthiest Christmas cactus on her window sill that I have ever seen!

Merciiii pour l’exemple de par chez nous!

Great to see you back Dr Gray

I'm terrified by the thought of separating those thin lego blocks

"Vega" signal from the movie Contact !!

My favorite astrophysicist is also poetic! Thank you for sharing, Dr. Gray. =)

Visual aids are so incredibly helpful in science- one reason why I like Prof. Merrifield is that the guy always has paper and a sharpie at his side, along with amazing drawing skills!

Awesome, as usual. Keep it up :)

I propose the lego brick to become the new international standard for measurement, who's in?

Cool video! I have a question! Does earth's atmosphere experience tides similar to the ocean? Wouldn't that make the height of the Karman line variable?

14:11 Much love to the editing crew for putting in the transmission sound effect from Contact.

I have always enjoyed Meghan's videos but this one was particularly enlightening. I really hadn't appreciated how varied the heights of the different satellites were.

Sound from “Contact” was great👏

I like the little throw-in from the movie Contact

I just quietly, (loudly) fell in love with you guys. Respect! Amazing demonstration. I hope everyone on the planet gets to see this!

Thank you for the Canadian reference, really put it in perspective for me!

I heard the signal from Contact in the background on the geosynchronous satellites graphic 14:12.

Beautiful Christmas Cactus!

one of the best explanations of how thick the atmosphere is, seen by me on some tele program, was take a basketball, dunk it water, and the thickness of the water when you take it out is about to scale! i really don't remember who the presenter was :/

Man, that really puts the Lunar missions into perspective. Incredible that they pulled that off. Several times even!

14:!3 Nice touch using the transmissions from Contact as a sound effect.

Love this video!

This could be very important, because hypothetically If you put a space weapon just outside of space then it doesn’t violate the treaty.

Yep, nothing near Adelaide, and that's the way we like it 😀

Now try pulling these Lego-Blocks apart again... legends say fusion occured between them and they shall never be separated again

Thanks you! I’m in Montreal

Nice comeback with the Adelaide!

I think a better title would have been "Where does space begin?".

love that contact reference at 14.15 :)) great video overall

Well explained

Always fun to hear Meghan's Haligonian accent interspersed with a few words with clear British pronunciation :)

The proposed 80km or ~50 miles seems a fair amount considering the papers you read from ( and anton petrov description of it, that already formed an opinion in me ).

Fantastic video and such a great channel! Timely too. NatGeo just published a video looking at people who, um, fail to accept the shape of earth as outlined and depicted herein. ;) The edge of space, so close and yet so darn hard to get to.

Please make a video about the edge of the Universe where all the space ships fall into the abyss when they cross it.

Thanks for using the Vega signal from Contact.

Great video

That satellite chatter at 2:00 makes me think of playing Deus Ex.

"And as always..." 10:10 For a split second I waited for a Vsauce feat hahaha!! BTW, lovely video as always.

I watch your presentations .. do I don't understand that very much .. but it is very informative .. and you make it so interesting too... being an expert you pull-in as lecturer .. I am just interested in knowing ...about the space and space travel

You do see borders from space, not most of them, but definitely some, the border between north and south korea is pretty prominent. You also see how huge the earth is, how many resources there are to exploit, how many forests we have, how huge the ice caps are, how big the ocean is, how much land there is and how little of it we use.

great video

Isn't the other big political issue not so much the range at which you can launch missiles but the range at which a country's "border" ends going upwards. Ex. A satellite at 100 km above the US/CN/UK/etc. isn't in those countries technically It's in the space above those countries. So no foreign craft is technically infringing on the sovereignty of those nations.

NO EDGEEEEE -hank green

I can only imagine, but I imagine that the three big mind-blowing moments from those "near space or maybe actual space" experiences are: 1) Weightlessness 2) Seeing the curvature of the Earth 3) Seeing the sky be black (or almost black) even though it's during the day And as a bonus I would say, having it all last as long as possible. If your space tourism has those three (+1), I think people will count it and pay for the experience.

I enjoy the Contact sounds @ 0:13 =)

Cheers from Adelaide!

Great video, I like the mesopause definition since it kind of agrees with the satellite death zone but is more definable

So I think part of the reason space feels so far away is because of how hard it is to get there. Can you do another video on the energy to get to space? For example if it takes two gallons of gas to get from NYC to Philadelphia, how many gallons of gas to get the weight of my car to 80 km? Karmon line? ISS, etc. How much more gas if I also have to get the weight of the gas up (ignore weight off tank)?

I didn't realize there was even a debate about this. I had always thought that it was 80km. Kind of interesting. I wish I knew what had given me that perception.

The statement "Seeing nothing but the infinity of space" at 11:29 spawned in me the realization that space is indeed endless but our small minds are incapable of discerning that value or non-scalar magnitude.

Sample from movie "Contact"? Nice :D

For some reason I was expecting a video about the edge of the universe but this one was very interesting nonetheless!

9:55 The bus passing by in the window when she says she had the ISS overhead, then a person walking by while she remarks about there being people up there.

You could add an intermediary zone. Definitely not-space being bellow 70 km, with pseudo-space (or whatever you want to call it) being around 70 to 120 km. Then above that it's more "proper" space. And the technical definition could be that it's an area where orbits are possible but they almost always decay within X-to-Z number of days.

Nice reference to the movie Contact.

14:23 That blew my mind… I always thought geostationary orbit was maybe about a third of _that_ away. Wow.

@06:14 The great gray stump!

I really love, how foreign (not hungarian) speakers call hungarian scentists. John von Neumann, Theodor von Karman. However Theodor Karman (his hungarian name is Kármán Tódor) was in in fact a noble, but the von title is granted only for german nobles. John Neumann was accurately translated (John in hungarian is János), but he wasn't a noble at all. They were all the victims of the anti-semitism in hungary and had to leave the country.

I suppose that plenty of people in Montréal will be happy that they are closer to space than Ottowa (and vice versa).

When I was growing up in the 1970's I heard some people using the zoning terms 'near space' 'inner space' and 'outer space' - were these terms just fashioned for the media or were they defined? {Outer Space i'm fairly sure is still 'where the edge of our solar system is deemed to be', although where the consensus of that boundary is I think has changed too.}

At 11:30 you can clearly see some constelations like big dipper and orion right in the middle

You know.... The Challenger Deep is less than half a plate deep. The deepest borehole isn't any deeper. So we're farther up than down. Let that sink in.

آپ نے بہت اچھی وضاحت کے ساتھ ایک نیا تصوّر سمجھا دیا۔ شکریہ