Tides: Crash Course Astronomy #8
ฝัง
- เผยแพร่เมื่อ 19 มิ.ย. 2024
- Today Phil explores the world of tides! What is the relationship between tides and gravity? How do planets and their moons become tidally locked? What would happen if you were 300km tall? Important questions.
Check out the Crash Course Astronomy solar system poster here: store.dftba.com/products/crash...
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Chapters:
Introduction 00:00
Gravity Over Distance 0:44
Tidal Force Parameters 1:35
Battle of the Bulges 2:55
High and Low Tides 3:47
Push & Pull 4:51
Tidal Lock 6:07
Sun Tides 6:58
Review 8:51
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PHOTO/VIDEO CREDITS
Photo & video credit: "NASA's Scientific Visualization Studio"
svs.gsfc.nasa.gov/cgi-bin/deta... Photo credit: "NASA's Scientific Visualization Studio"
www.flickr.com/photos/gsfc/85...
svs.gsfc.nasa.gov/cgi-bin/deta...
The Hopewell Rocks - • The Hopewell Rocks - O...
"tide go in, tide go out. you cant explain that."
~bill o'reilly
i love that he'll never live this down
Checkmate Atheist's!
I face-palmed so hard when I first heard him say that...
He really said that? Pretty sure I have known how that works since 5th grade. Thank you PBS.
Did someone really say that? I knew roughly how tides worked when i was about ten. And i didn't even see the ocean until i was thirteen.
Bill O'Riley
I'll say it every time - this is my favorite Crash Course, and Phil Plait is absolutely fantastic at this.
Yes, agreed. He's very good at explaining all things astronomical.
Fred
Yeah, this is my favorite topic of CC Astronomy so far.
I was forever wondering how the moon affected tides. Thanks, Phil, for making it simple to understand (to an extent, I'll need to watch this again) and entertaining!
Woodenfan I shouldn't play favorites, but I can't help it - this is one of my favorites too :)
-Nicole
Digging that reference at the beginning :)
Pretty epic
I knew about tides. What I *didn't* know was why they worked on the other side of the planet. And most especially, I didn't know that the Moon was getting *further* from the Earth - I thought it was slowly getting closer, because of gravity. Crash Course continues to inform and educate me.
+Woodenfan You are the best anime btw
His accent and his phases of speaking is really clear. It's easy to understand without subtitle. Thank you for uploading these videos. I can't imagine how am i gonna survive through the semester without this channel.
Maybe I'm dumb but I've watched this at least 8 times in the past 4 years and I still don't understand
try getting grip over other facts about the relative movement of the Earth, the sun and Moon, would certainly make it easier to imagine and understand.
Basically the moon pulls the water a bit towards it which makes it go up, and then it later goes down
The part that baffles me a little bit is how the other part of the earth gets a bulge ..like I get what he is saying I'm just trying to see how this works a little more ...I wanna dig little more in this
Thank you for using the metric system when explaining!
all this gravity talk is weighing me down
Just... Dont.
You can leave
@@pixii_9314 He can't, there's a lot holding him down.
bahahahahaahaaa ^_^
@@anujd9082 It sucks he didn't think to say that
"Tide goes in, tide goes out. Turns out I can explain that."
-Phil Platt
Greatest moment in Crash Course Astronomy so far.
+
I'm re-watching this series 2x or 3x per episode, let me tell ya, I love this shit.
This just blows my mind. So many forces at work yet most people have no idea. Loving this series.
Shout out to the spaghetti monster cameo.
DoctorShuckle Thought Café is always bringing fantastic special guests to the party ;)
-Nicole
All hail Zeus.
R'amen!
have you been touched by his noodly appendage
All hail his noodleiness
And of course I'm watching this because I enjoyed a lovely spring tide on the reef today and live on the coast. You guys rock.
Crash Course needs to make a full length version of the theme song so I can jam out to it while I study!
I'm loving this series, it's a great intro to Astronomy
OH SNAP! Dat O'Reilly reference...
If anyone is ever in Nova Scotia, watching the tides come in the subenacadie river is amazing. It's close to the hopewell rocks shown in this video. All of this is in the bay of fundy. Highest tides in the world! Tidal bore rafting is a blast too!
Astronomy is one of my favorite subjects in Science
My favorite answer to the question of what's up? Is up is the abstract concept of the direction opposite the nearest greatest force of gravity
RDeathmark What's new? C over lambda.
RDeathmark What's up? The normal force.
2022: In my opinion still the best video on tides. Thank you very much!
Fantastic video. It's like "tide" isn't even a word anymore.
Did anyone forward this to Bill O'Reilly yet?
I don't think he's interested in facts.
I'm curious how many links Bill'O gets in his inbox every time new educational media is released on the subject of tides.
Tides go in tides go out therefore Jesus did it all hail the flying spaghetti monster
culwin Given his recent runs of busted lies, I think you're right.
Wow, you are sooo cool, making fun of someone you have no knowledge of; stupid hipsters.
Crash course philosophy is the dream, but this will suffice
Why do you say that?
***** have you studied philosophy. There is a hell of alot more to it than that. Logic, metaphysics, religion, and that's just to start. I would love a crash course philosophy. I need to figure out if subbable or whatever that is that funds them has something that would allow me to donate toward that.
***** "Well, the borders on thoughts are supposed to be regulated by logic."
I am not sure what this sentence means. How is a thought to be bordered, when it's hard to argue it has a spatial dimension? Are you talking about what cannot be thought? Or the logical policing of thought we call 'reasoning'?
Because what limits thought certainly isn't what we'd call "logic".
Logic is a game of truth and validity, strictly: what follows from some propostion/idea/statement. Of course we're led to "how?". Logic concerns itself primarily (and some would say solely) with structure. And the ability to evaluate arguments according to the laws and tenets of logic is indeed a very important and practical skill, but let's not be overly reductive!
Cheers
Crash Course: Philosophy (and/or History of Philosophy)
Yes, please!
It all depends on who hosts it, though. I don't think any of the current CC lineup would be very good at it. John is closest, but his style is not quite right for it.
Maybe... Michael from vSauce? :D
This just blew my mind! One of the best crash course episodes so far!
Great, for the first time I could actually understand (and accept) that there is one portion of the moon that is never facing the Earth, though is not really dark, we just can't see it from here. Well done, thanks a lot, mate.
awesome episode as always
lulzmort silvers Thank you!
-Nicole
CrashCourse I wouldn't mind if you upload a new CrashCourse Astronomy every day..or every hour. Please do more! At least 200 episodes! DFTBA
Thank you so much for explaining this! I've seriously been trying to work it all out on and off for a few years now. The pattern of tides and the moon's effect on the Earth were two mysteries I wanted to solve, and now I see they have one answer. You explained it perfectly :D I'm so thrilled to finally get it!
These are still my favorite cc videos ever! Phil is a badass!
Great jab at Bill there, I was really looking forward to one and you didn't disappoint! :D
Tide comes in, tide goes out - you can't explain that.
Jordan O'C
LMAO
Jordan O'C Best comment all day!
Gytax0 Damn, I expressly clicked this video just so I could post those same words. Beat me too it! Ha, ha!
Bill knows exactly how tidal force works. After all he covered 4 tides with a pen. You could also say he has been to an active tidal zone. :D
what do you mean with, you cant explain that???
You explained a very difficult topic in less than 10 minutes and made it very clear. Well Done!! That's how science should be taught!
Excellent. Thank you for the clarifications Phil. Keep it up.
How amazing ! Thanks Crash course, eventhough I have different speciality, I always love watching the variety if subjects you offer :) :)
One of the most detailed description of the tide effect I have seen. Very well done!
Someone send this to Bill O'Reilly so he'll learn something. P.S. Is it just me or did anyone else notice the Flying Spaghetti Monster near the end? All hail o great FSM!!
This is my favorite channel !!! so enlightening... never fails to conciliate my curiosity !!
I was reading about tidal locking just the other day. This was a really great explanation with the added graphics. Thankyou!
You briefly confused everybody who doesn't think of Football as American Football with your "Football shaped Earth" analogy :) .
ARG! I should've said American football. Nuts. Sorry.
tanner1ie Your comment confused Americans who are thinking, "What other shape would a football be?"
BamaFanEdge
:) .
Rugby and Aussie rules fans would get it.
Jim Fortune
I thought of Aussie rules fans, that they'd call a Football a more oval object than a round one, but on Rugby, while i know you can call Rugby, Rugby Football, surely when most people talk or think of the ball used in it, they call it a Rugby ball, not a Football.
So they likely wouldn't instantly think of a Football as being oval :) .
These videos have been amazing. Thank you very much. I hope you go very deep in astronomy. Including astrophysics concepts! I'm following the uploads each week since the beginning and I'll keep doing that. =)
This is the best video for this course. So far.
Brilliant O'reilly reference in the thumbnail.
This episode has particularly great illustrations of the subject matter. I wish I'd had this when I was going through earth science class in school!
Idea for pickup line: "Girl, it must be high-tide, because you got me bulging."
@Dominic Stephens 2016 was a different time.
Thank You Phil. It is by far my the most favorite episode!
wonderful explanation and images to follow; thank you!
I guess you can explain that.
drz ha! I get it.
For a very interesting - and somewhat disturbing - example of these ideas, read Larry Niven's short story, "Neutron Star".
+Julie Ritt I love that story!! However, it causes a major inconsistency in Niven's Known Space. Latter, in Ringworld, we learn that the Puppeteers moved their home world into the Fleet of Worlds. There is absolutely no way that they didn't have an extremely good understanding of tides.
Amazing episode! Can't wait for the next...
Thanks for the awesome videos. Phil is great, as is the whole crash course team.
There two points on the distinction between tidal forces and their effect as seen on the earth which I think should have been made:
Firstly, the atmosphere also experiences tides (and those are more pronounced and match the tidal forces' bulge more closely than sea level but obviously they're not really a part of the common human experience)
Secondly, there is actually a much more complex relationship between the actual sea level and tidal forces than a simple phase shift implied in the video (land getting in the way, straits constraining flow, bodies of water having natural resonances with respect to the tidal flow, the actual currents within the water, the depth of the water, etc etc) that make the actual sea level changes diverge from the force of the tidal bulge considerably.
To actually predict sea level a more complex model model with lots of terms of different magnitudes and periods, and even so that's still just an approximate model.
c.f. ?v=3bQz6k2FRu4
@@foobargorch actually the tidal force is not real
WHY IS THIS SO CONFUSING 😭😭
Thank you! This is the best video about tides I've watched.
That was incredibly interesting. Didn't know that tides could be that complex.
That's the first time I've actually understood why tidal forces increase the orbital distance and why tidal locking happens. Thanks Phil!
I came in like: "Tiiiides... Everyone knows about tides... So boring... The Moon pulls on the ocean and blah blah blah... Talk about something cooler!"
Man was I wrong.
So why do large land looked lakes have NO tide
They are not 300km tall (deep). Even less than the diameter of the earth.
Actually the explanation in the video is incorrect, and a very good question is WHY don't lakes (or your bathtub!) have tides?
Thank you for the many subtitles.
I never get tired of watching crash course videos.
“What comes up comes down”
-Isac Newton
(Real quote)
Not if you throw it fast enough ;)
Teacher told the class to watch this for Science homework and i think my last brain cell left me and went to a trip to the Bahamas. the things i do for school
(btw whos from 2020?)
ME!
Me
Stay in school, kids
俺だ
Me
These are amazing! Thank you for continuing to make education fun!
Excellent video. Thank you
He reminds me of Harald Lesch in alpha-Centauri. That's a good thing.
alpha centauri gibt es leider nicht mehr, stattdessen haben wir jetzt lesch's kosmos:
www.zdf.de/ZDFmediathek/kanaluebersicht/925180#/kanaluebersicht/382/sendung/Leschs-Kosmos
OK, I know he's trying to keep this relatively simple, but I'd like to have heard him add the part of tidal-force effect that's so often missed - namely, that along with the stretching of an object along the to-from line, there's also a "squashing," or compression, along the transverse (perpendicular) directions, that''s half as great as the longitudinal stretching force.
While the stretching is a consequence of the change of gravtitational force with distance, the compression is a consequence of its change of direction with sideways displacement; so while it's pulling harder on your feet than on your head, It's pulling your left and right arms toward each other, and your back and belly toward each other.
This effectively doubles the "spaghettification" effect, with stretching forces along one axis combined with squishing forces along both of the other two axes, each half as great as the stretching force.
[/end of CrashCourse-level explanation . . /begin adv. calc behind it]:
The technical side of this is, tidal gravitation is the spatial gradient of the gravitational force vector; so it's a second-rank tensor that's traceless, its diagonal elements being +2 for the stretching direction, and -1 for each of the other two directions; so its trace = +2 - 1 - 1 = 0.
In other terms, the trace of that tensor is the divergence of the force, which in turn, is the Laplacian of (minus) the potential.
But the potential is a harmonic function, with Laplacian=0.
tr(∇⨂F⃗) = ∇•F⃗ = -∇²V = 0
This also explains why tidal gravitation drops off as the inverse *cube* of distance, because
d(1/r²)/dr = -2/r³
Oh, and I should have mentioned - the foregoing is not a criticism, but more of a supplement; I find this video very enlightening, and extremely well paced, thought out, and presented.
Like all the others in Phil's series of CCA videos.
Fred
This one made me smile! Might be my favorite episode so far....tough choice
Awesome episode. Thanks guys!
the guys at PBS space time proved that this explanation is false, here's the video v=pwChk4S99i4
may be it's time to make another video to correct this one!
+nabil adoui I was about to mention this as well. Would be interesting to see what Phil thinks about it!
+nabil adoui you know what's funny (and awesome, which is why i love science and open discourse without negativity). it's from this series of crash course (i think the one on black holes) that i found PBS Space Time. a viewer recommended it as a more detailed explanation. after all, this is "crash course", not "detailed study." then going through every video for PBS Space Time, one of the two links in the description about tides links to this one, which is why i'm here again almost a year later after watching it for the first time.
i'm a nerd and as lady gaga said, i was born this way :)
+ucraznmonkey hey, you're not the only nerd :D
yeah the guys at space time do a more detailed explanation, and it requires having some background in science, and that level of detail is what I love about there show
+nabil adoui Thanks for the link. You're right, the video you suggested does a much better job of explaining the tides.
Maybe we shouldn't have been so hard on Bill O'Reilly?
Duane Degn
we can give Bill a pass this time :)
"If you just sit in your house all day" - how did you know???
It is called research, self-based analogies, diagrams, and a script, alright? He isn’t going to travel to space to track the records for a 9 minute PBS video. So ya know chill aight?
this keeps getting better and better! keep up the videos guys!
thumbs up for showing the tides in NB canada!
"Battle of the bulges"
L ! F Ê ha
So, have you ever REALLY wanted to hit Bill O'Riley?
This was really useful, clears up so many misconceptions!
Crash course is a freaking dream come true.
Do we measure the distance between two bodies in space from their surfaces or their centers?
We measure from the center of mass (you could say where the gravity is pulling you towards)
Like what others have said: From the center of mass. When calculating flight paths and gravity assists and orbits of space crafts, I expect that is the only best way.
Rick Seiden I have seen, say, the distance to Jupiter's ring to it's cloud tops, but I think that may be mostly used in popular science. Not much useful or accurate information can be gleaned from the distances between objects EXCEPT by the center of mass. Measurements of mass and densities of worlds were calculated to decent precision long before the Space Age by utilizing the formulas of Isaac Newton, who created the formulas using the centers of mass.
gardener68 I'd like to add that the masses couldn't be worked out until the Cavendish experiment (aka "Weighing the Earth") in 1798. Big G wasn't known in Newton's time, which IMHO makes his achievement all the more impressive.
Secondly, the validity of using the center of mass of a symmetric object was proven by Newton, it's known as the Shell Theorem and this was a crucial step in making the laws applicable to astronomy.
***** see Kepler's third law (the cube of semi-major axis of the ellipse is proportional to the square of the orbital period)
I like gravity
Me too! :)
I kind of hate it, it's always putting me down...
Yeah it's kind of a drag
I like turtles.
chris patry foreverwantingpie bless you two XD
Love this channel. Thank you for another great video.
Wow, fantastic episode. Great visuals and explanation.
"It becomes ever so slightly football-shaped."
But a football is round! A hand-egg on the other side...
American football
"The slowing of the bulge"
Wouldn't this have been the best episode to talk about the Roche limit?
This is so helpful as I'm studying for my astronomy 101 final. Makes so much more sense now. Thank you.
Okay,okay this guy ruined life for me by making a educational video
I thought that he's gonna talk about how the Sun will eventually tide lock the Earth, boiling one side and freezing the other (I guess)
Omg I love this it explains everything perfectly
Your videos are incredible!! Thank you!!
"The bulges pointed right at the moon."
Wtf is going on with the tides near Argentina around 3:50?
I'm no ... tide ... ologist? But I think it has something to do with the sea-floor and the shape of the coastline around Argentina that makes the tides slosh.
From en.wikipedia.org/wiki/Tidal_acceleration#Angular_momentum_and_energy
The rotational angular momentum of Earth decreases and consequently the length of the day increases. The net tide raised on Earth by the Moon is dragged ahead of the Moon by Earth's much faster rotation. Tidal friction is required to drag and maintain the bulge ahead of the Moon, and it dissipates the excess energy of the exchange of rotational and orbital energy between Earth and the Moon as heat. If the friction and heat dissipation were not present, the Moon's gravitational force on the tidal bulge would rapidly (within two days) bring the tide back into synchronization with the Moon, and the Moon would no longer recede. Most of the dissipation occurs in a turbulent bottom boundary layer in shallow seas such as the European shelf around the British Isles, *the Patagonian shelf off Argentina*, and the Bering Sea.
Most awesome topic, I was always confused about it, thanks!
I have been (admittedly casually) looking for an explanation that put the acceleration in it's orbit, and the consequent increase in the distance between the moon and the earth, for a long... LONG time. Thank you for this video, I'm so happy to have found it.
hi im at home and doing homework on that :)
#watchedbefore301views
Len Huang #achievementunlocked
-Nicole
ermagurd
a response
from CrashCourse-Sensei
*faints*
LOL back when that was a thing
This is one of the best explanations of tides I have ever seen!
Excellent episode!
His Noodliness boiled for your sins!!!
Oh pasta, who art in thy colander, Draining be your noodles. Thy noodle come,
Thy sauce be yum, On top some grated parmesan. Give us this day our garlic bread,
And lead us not into vegetarianism, but deliver us some pizza,
For thine is the meatball, the noodle, and the sauce, forever and ever. R'amen.
BLOODY BRILLIANT
dear editor: your audio cuts could use a little more breathing space. it's sounding unnatural.
Mind-blowing explanation !
I actually didn't know about the mechanics of the high-tide on the opposite side of the moon.
THANKS FOR LEARNIN' ME NEW STUFFZ!!!!
This is for kids but you're way too fast for them
The gravity between the earth and moon has a bigger effect on the moon, but that isnt because the "amount of gravity" that the earth "inflicts" on the moon is greater than the other way; it's because the moon is less massive and thus has less inertia. The gravitational force exerted on the earth by the moon is *exactly the same* as the force exerted on the moon by the earth. Newton's third law. This may seem counter intuitive at first, but there are plenty excellent videos on youtube explaining why it must be that way. So instead of thinking of the gravity between the moon and earth as somehow two separate things, it's more helpful to maybe think of it as a "gravitational link" or bond between the two, and the force is the same in both directions. But because the earth is a lot more massive, it has a lot more inertia, so the *effect* on the earth is less, but the actual *force* is exactly the same. This may seem like nitpicking but I think it is an important distinction to make.
Epic slap to BillO.
:D Made my day.
Thank you Phil.
I am emailing this video to Bill O'Reilly. Who's with me?