Why Starlight is like Rain - Sixty Symbols
Vložit
- čas přidán 13. 07. 2024
- Professor Mike Merrifield discusses the stellar aberration and the acceleration of the Sun.
More links and info below ↓ ↓ ↓
More with Professor Merrifield: bit.ly/Merrifield_Playlist
Gaia Early Data Release 3: www.cosmos.esa.int/web/gaia/e...
Visit our website at www.sixtysymbols.com/
We're on Facebook at / sixtysymbols
And Twitter at / sixtysymbols
This project features scientists from The University of Nottingham
bit.ly/NottsPhysics
Patreon: / sixtysymbols
Sixty Symbols videos by Brady Haran
www.bradyharanblog.com
Email list: eepurl.com/YdjL9 - Věda a technologie
It is mind-blowing! The sun travels with 220 km/s and we can measure an acceleration of 1cm/s in a year!
Right!
The most mind blowing part to me is that you and I could apply their technique and make the same measurement with little more than a camera, telescope and ruler.
@@eideticex Sure, if your telescope is GAIA's astrometry instrument, your ruler is its radial velocity spectrometer, and your camera is 1 gigapixel. (You can't measure the Sun's acceleration from home.)
The velocity of Sun rotating about the center of the galaxy should reverse completely in half a turn which takes 440000/0.01 years. So the sun completes one revolution around the center of the galaxy in 88 million years. If the orbit is a circle its diameter would be 2x10^17 km!
Our psyche is part of nature, and its enigma is as limitless. Thus we cannot define either the psyche or nature.
I've been watching this channel for years and had no idea that was THE Mike Merrifield from Astronomy textbook fame. I've been reading them for my studies for ages and now have a much greater appreciation for them! Thanks for such informative videos Brady and Professor Merrifield!
GAIA is so underrated in popular science.
Why isn't it visible in the night sky
@@prateekgupta2408 You mean the spacecraft? It's 1.5 million km away.
Dr Merrifield is just what i needed on a rainy day like today ❤️
rainy rainy frog goes go croak the bee go bzzzzzzz
Its Professor Merrifield
Regarding the question where the _energy_ for the measured acceleration comes from: NOWHERE. No energy needs to be transferred to keep an object in circular motion. You need the gravitational _force_, but that force doesn't need to do any work because it's perpendicular to the velocity of the solar system. That also means that the acceleration in this video doesn't correspond to a change in speed, just in direction.
But here again, the idea that gravity is a force.
Hmmm. It makes so much sense to think of it like that.
But..
Exactly. I felt Dr Merrifield was very misleading saying multiple times that the speed of the sun was changing. I feel like he missed the fact that he and James didn't understand 'acceleration' in the same way (acceleration as a change in direction instead of speed can take a bit of wrapping your head around even when explained properly).
@@Varksterable Newtonian gravity works exceedingly well in most cases, even though you're correct that gravity in Einstein's General Relativity is not a force like all the others.
@Teacher Hayes Yes, glad someone commented on this! I agree!
You can't assume the gravitational force acting on the Sun is perpendicular to it's velocity. For one thing, there may be some eccentricity to the Sun's galactic orbit. For another, we are significantly affected by nearby stars, causing accelerations in basically random directions over millennia.
Interesting video. But I hated the audio waveform effect on the screen.
Same here, weird eh?
The anxiety of watching Prof. Merrifield swinging his precious head towards that beam... Careful - we need you to keep using that!
Love this channel!
Love this comment.
@@sixtysymbols love this reply!
Oh get a room, you two. ;-)
Interesting interview, always a fan of Prof. Mike Merrifield. Not a fan of the bar waveform effect at the bottom of the screen when the both of you are on screen lol
I spent months dealing with complaints about the brown paper in my Numberphile videos... Now I get complaints if I don't use it!!!!
@@sixtysymbols The brown paper contains useful content. The waveform does nothing to help understand the material.
@@sixtysymbols Um, what? The waveform didn't bother me, personally, but what is that reply about?
Go easy on the pre-Christmas sherry, please. We want you back next year!
@@sixtysymbols I don't hate it, don't get me wrong. The quality of your content is incredible, the animations are always insightful and on the topic of the video. I'm always paying attention to the animations, and I had felt that this one in particular didn't quite fit in
@@jeanbigboute - How does brown paper contain more "useful content" than white paper?
Awesome content as usual
Thank you - you're very kind.
Just for fun, I calculated how much mass is contained within the Sun's orbit around the Milky Way, based on those numbers. That comes up to approximately 102.8 billion solar masses, assuming a perfect, or near perfect circular orbit.
Well, considering the milky way has 100 billion stars and most of them weigh a little bit less than 1 solar mass this seems about right.
@@Thror251 - The exact number is "billions and billions".
Brilliant as usual. Thanks
Thank you - glad you liked it.
The equalizer graph at the bottom of the screen is very distracting and hard to watch. Otherwise a great video!
What Graph? :O
@@lynx655 1:46 ← It's during their side-by-side video here.
Agree.
Here here!
I love Brady's videos, but that was... an aberration.
Yes, its so awful!
this was the first channel i subscribed to and it was the only one for a looong time. :}
thank you again for the great content, everyone involved
measuring 0.2 nano meter per second acceleration on a speed of 220 000 meter per second. thats some sensitivity of several order of magnitude
Me at start of video: It's going to be a small number. Er, 2X10-10m/s2. OK, that is small..
The rain graphic was excellent and instantly made the concept click (at least a little) thanks Dr Brady and Professor Merrifield!
Good day Dr. Brady
Very exciting to have the 3rd data release from Gaia; this will help with photometry a lot, especially with the Milky Way's satellites.
It's incredible how we take knowing the position or movement of stars for granted, seeing how many factors there are in calculating it. Really interesting video.
Its not _that_ incredible when you think about the timelines. We were still debating whether our galaxy was the entire universe less than a century ago, and even once we'd sorted that out we still were pretty clueless until that famous Hubble Deep Field in _1995._ Its only been 25 years since we finally realized the true scale of the (visible) universe.
That's not anywhere near enough time to change the existing conceptions of the entire population, many of whom still think the course of their life is determined by the motion of the the nearest few hundred stars relative to only six of our solar system's eight planets.
To those of us who actually follow cosmology, even in a fairly casual context, it seems like this stuff has been known "forever", especially when much of the foundational stuff we're taught in the introductory and high school courses was worked out by folks during the enlightenment. But in some ways our modern understanding of cosmology is newer than things like gene splicing or even the internet where most of us learn about it these days.
Just to be clear, obviously _some_ people believed the universe was bigger than we knew about prior to 1995 - otherwise nobody would have bothered wasting a large amount of Hubble's time pointing at an "empty" patch of space in the first place.. but prior to the Deep Field image, we had no real evidence either way and there wasn't a general consensus at the time that we'd find anything in those "empty" patches.
Thanks for the video. Wonderful.
You are welcome.
WOAH 😳, I spent many hours in my younger days pondering this very thing, ie , if your moving then should the source of light appear to change position .
It turned out to be a question I never asked, I assumed that if I was thinking about it then many a greater mind than mine had already thought about and solved this ‘problem’ .
It’s so nice to hear you guys speaking about the thoughts I had when I was in my youth , and of course I was right , a far greater mind than mine had pondered this and proved it to be true .
Lovely bit of production work as James Bradly and John Herschel "comes into focus". :)
holy moly I just learned about this luminar paralax stuff and its amazing!
Like whaat we see sth in a different place when we move perpendicular to the light it produces?? this sounds crazy!
Incredible story of understanding our place in the galaxy.
dear lord that flashing voice spectrum along the bottom really shouldn't be there. This isn't a podcast, I'm trying to watch it!
It's not a "spectrum", it's a waveform.
@@RFC-3514 ah, you're right.
@@mininukes4ever - A spectrogram would actually look nicer and be less distracting, IMO.
Totally missed the fact that the result wasn't quite what we've expected. Sun is apparently closer to the centre as previously thought
Incredible data from Gaia.
That's a very good analogy..
That is so cool. Had no idea.
This i really great stuff. And I agree with my former commentators in two thing: Gaia is a heavily underrated mission and the sound spectrum steals way too much attention for no reason :)
The Sixty Symbols weather man is back!
He loves a bit of weather! bit.ly/Weather_Videos
Gaia is my favourite spaceship now but when I first heardve what it was going to do I thought eh ok I guess but I just never imagined what ppl could do w that data. but soooo many cool papers keep coming from Gaia data all different stuff that we understand now that we had no clue before
Nice
It's great they got Murray from Flight of the Concords to run the interview.
This should have come out before my Gaia essay....
all right, time to watch it a second time to understand what this is about.
With GAIA data can they calculate the fine structure constant at a million points?
Please, get rid of the equalizer !
Well, it's too late now!!!!!
@@sixtysymbols pffft
no, i like it
What "equalizer" ?
@@RFC-3514 Those waves displayed in the form bars when someone speaks.
Stellar Cartography v.01
With conflicts between the Hubble constant, the accelerating expansion of the Universe from dark energy, influences of dark matter, and on and on I'm surprised they can measure anything to this accuracy.
That's simple: neither the Hubble constant nor the scale factor enter this equation. Also, any tiny acceleration part from dark matter is just that: a small fraction of the measured value. Note that the measured value has only 2 significant digits, so it's fair to say it is not "accurate" at all. We can measure everyday distances to 4 digits accuracy with household items, e.g. your height in mm. Don't confuse accuracy with absolute value. This is not to say GAIA isn't an outstanding mission!
This is so confusing after reading so much that gravity is an illusion and orbiting bodies don't actually experience any acceleration, but follow a straight path in curved spacetime
We measured 1% of our galaxy with Gaia. That probably doesn't seem like a lot to some people but if you can even just attempt to think about how big of a leap that is from not even knowing there was more than 1 galaxy out there, it's hard not to find our world incredible!
been a while since I was in school but shouldn't most of the instances where the professor uses the term "speed" be replaced with "velocity" instead since there is a directional component?
Not if he only cares about the magnitude of the vectors. Otherwise you would be right.
very poetic title brady hahaha
If parallax can be measured by acceleration, wouldn’t an observatory in a highly elliptical orbit around the earth (where it speeds up towards the focal point and slows down towards the apogee), be much better for measuring the parallax of stars?
Shouldn't measured acceleration be greater than calculated due to dark matter?
This channel only for legends❤✔
How did they separate the motion of the Milky Way relative to the quasars?
The angle of light coming from the quasars is tilted in the Sun's reference frame compared to the Milky Way's reference frame. The direction of this tilt also changes as the Sun orbits the Milky Way.
Would anybody else like Prof MM to tackle Halton Arp and intrinsic red shift?
Awesome video! Big fan! But, please lose that “audio level” graphic. Yah, no.
What can we deduce about dark matter from that data?
Gaia is the mother of Uranus.
What's the acceleration of the Sun relative to the local standard of rest?
probably a bit slower than the stuff closer to the middle of the galaxy and a bit faster to the outside stuff lol but in all seriousness it would probably differ by a few percent at most
Bradley looks almost identical to Bach in that portaite
This kind of science I love so much, it's way more convincing than biology (the field in which I worked). :)
Not more convincing, but just more understandable, surely?
The complexities of biological systems seem at the moment to far outstrip things we seem to know about the astronomical universe in terms of complexity; I agree with that.
But that doesn't mean any conclusion in one is any more convincing than the other.
The two do seem in some ways to be converging. Wouldn't it be ironic if the knowledge we gained from studying biology ultimately explained gaps in astronomical understanding?
There have already been connections hinted at (shown?) between biological systems and quantum theory.
Personally, I think it's only a matter of time before everything becomes holistic and we can all just go down the pub and relax. (Assuming lockdown has ended by then.)
@@Varksterable Our psyche is part of nature, and it's enigma is just as limitless. Thus we cannot define either the psyche or nature.
More, please!
There's always more coming! That's science.
No media hype about Gaia satellite because it's European satellite.
Wouldn't placing GAIA in the first Lagrange Point of Jupiter render more precise results? Baseline would be larger and thus paralax would be larger.
It would take 12 years (Jupiter's orbital period) to get a complete data set. By the time you designed, launched, traveled, and got your first data set it would be 20+ years. Given the lifetime of a RTG (which you'd need) you would get about 4 or 5 datasets before the satellite's life was over. We can get a 3 cm/sec sq accuracy from an Earth based satellite. How much more accuracy do you really need? Is 20+ years worth it?
@@stevengriffin1758 Thx for your insight. Long cycle time is indeed a downer. Don't think you'd need RTG (Juno doesn't need one) and don't think anybody would complain about too precise measurements, but it's probably simply not worth the effort.
6:07 I thought I could smell bacon.
happy Xmas and a Merri Feild Year
_waiting for people to realize we can build telescopes that are 1km^2, space based, adjustable full parabolic, metallized foil, fault tolerant,
Man is clever but not wise
Yes!!!!
How much more parallax would you get from putting 2 telescopes in orbit out past Pluto, on opposite sides of the solar system from each other?
It has almost been done - do a search for “NASA’s New Horizons Conducts the First Interstellar Parallax Experiment.”
Something like a 35~50 x longer baseline to measure from.
This is confirmation of what we already know, is it not? I mean it is kind of an obvious fact that the sun goes around the milky way and therefore has to be accelerating?
Didn't know Bach also dabled in astronomy
A little clarification of the term "Acceleration".
Most people use the term acceleration to mean a change in speed. As in a car stepping on the accelerator or stepping on the brake to slow down.
In physics speak "Acceleration" is not a change in speed but a change in velocity. Where velocity is a vector; with magnitude (= speed) AND direction. A change to this vector is an acceleration. That can be a change in speed or direction (or both). The speed of the Sun does not change, but it's direction does.
That's why things orbiting a centre of gravity are constantly accelerated, that's why you feel a push when going around a corner in a car …
Most people use the word acceleration to mean a change in speed, in the increasing speed only.
They use deceleration to mean slowing down. Well, they actually just say slowing down. But you know.
@@lordgarion514 Yeah, just like 'go with the flow' means something very different to a hipster than to a fluid dynamicist. 😁
It's odd, given how many letter combinations there are, that so many are overloaded.
Like the word "overloaded" for example.
Each niche use assumes all the other niches see the nuance. But do you mean 'carrying too much weight' or 'having multiple meanings' or 'a function with the same name but different parameter signature?'
It seems odd that such compromises are made.
Right up until you work in the financial, legal or military industries. Then you'd need to make up so many new words that even asking for a pint at the local pub would cause total brain meltdown.
So I contradict myself by concluding there are only so many words that a human brain can store. So let's reuse them. Mip mip mip. Mip mip. Mip? Mip.
Prof says "The black hole in a quasar is incredibly bright".
Black And Bright? Doesn't that sounds like a contradiction?
Isn't the the universe and our descriptions of it weird and wonderful.
Nope, because the black holes at the center of quasars are surrounded by immensely bright accretion disks formed by the devouring of matter.
I wonder wich of both measurements (or calculations) of the acceleration is more accurate or
trustworthy
The best axplanation I have seen of the acceleration of the sun so far
So science finally tamed the sun and installed a speedometer on it.
I vaguely remember learning about centripetal acceleration in school. For the first time Physics no longer seemed intuitive. (in that an orbiting body could be accelerating without changing its apparent velocity)
But since you are on the Earth (which is rotating), _you_ are accelerating without seeming to change velocity! It's pretty weird, right?
And when you go around corner in a car? Yeah; same.
None of those things seem like what we initially feel like what 'acceleraction' is. But acceleration is just a term. Which is _defined_ as that exact thing!
I can't define 'love' or 'art' or 'wealth' or 'happiness'. But I can define acceleration. Maybe that's what why some people are interested in physics, and some are not.
Dunno. Just putting it out there.
@@Varksterable Yes my mistaken assumption as a kid was that acceleration meant getting faster not that a constant force was being applied.
"Kind of completely" ??!?
Please don't do the waveform display. Eyes don't know what they should be looking at, faces or bouncy graphics and is almost nauseating. Thanks for another video with Mike!
Isn't the acceleration like g on Earth? Constant for every object orbiting the black hole of our galaxy. (same distance of course)
Why can't I see gaia in the night sky , please tell me guys
Because it is located 1.5 million km from Earth at L2.
The sound spectrum thing is seriously annoying.
Why? lol
Oh it is a little distracting I guess
The soundbar is quite disturbing, pls don't put it. Otherwise great content as always.
Wait, I don't get it, so what is the acceleration that is towards the center of the galaxy? (around 8:00 onwards)
Gravitational force gives the sun gravitacional acceleration towards the center, since it is in the center of the galaxy, the black hole there, that causes the gravitational force in the first place.
For an objec to move in circles, a force is required. But forces implie acceleration, like Newton said some time ago ( F = m.a ). Accelerations can not only change the vallue of the velocity but it's direction. That's why it's weird for us to understand that spining objects are accelerating. In the case of an orbit, only the direction is being altered, not velocity.
Got it? The Sun must be accelerating towards the center of the galaxy, because the direction of his velocity is being altered by the gravitational pull from Milky Way's black hole.
@@isacj81 I get that the acceleration on the sun is caused by the galaxy.
What confuses me are the images at 5:45 and 8:13. It's shown like it's the quasars that are accelerating towards the galaxy, not the sun.
Maybe I should put it like this, how do the quasars help in measuring the acceleration of the sun towards the galaxy?
@@mami42g The quasars are so distant we can assume, for the purpose of mapping closer things, that they are fixed reference points. It’s a lot easier to map motion when you have things that are apparently motionless to compare to. This is not to suggest the quasars really are motionless. They probably move through the universe similar to other galaxies. It’s their great distance that makes them appear approximately motionless from our perspective. Their immense brightness enables us to see them across the vast distances.
Why starlight is totally unlike rain - the light does NOT fall on you when it is cloudy!
every circular motion is an accelerated motion, even if the thing thats moving in a circle moves at a constant velocity. that confuses so many people^^
People tend to equate velocity (a vector) and speed (a scalar), so when the speed is constant they assume the acceleration (also a vector) must be 0.
"Starlight Rain" needs to be the name of something right now
Maybe 2021 will be a Starlight Rain year. Bring on those coronal mass ejections! Just exactly what we need right now. (Hmm, be careful what you wish for, you say? Why should that matter?)
What was the margin of error of measured acceleration?
@@flowerpot-h7p but thats 8 magnitudes bigger than 0.0....02 m/s^2
@@user-yc5fq9bv3u That should be 0.16 x 10^-10.
@@vimalramachandran makes sense now.
I actually liked the bottom soundwave thingy!! It's your call, Brady! We'll watch your videos no matter what
I don't mind the idea, but the actual effect used looked pretty crappy. Also, I suspect a spectrogram would look more interesting _and_ be less distracting than a waveform.
Please do not do that level meter display again.
Or at least chose a much, much more greyer grey for it. It looks cool but it is super distracting.
dr. brady, how dare you trying to hide your silky voice behind the crappy mic
Needs more brown paper. Oh, wait, wrong channel.
heheheh nokia funny arabic ringtone....lol fish on land العربية
@@tuneboyz5634 Can you explain that last message?
Man, this professor is loosey-goosey with terminology. Centripetal acceleration does NOT change the speed of an object; it only changes its velocity. And by a change in velocity, it only changes the *direction* of the velocity, but not its magnitude. But if the velocity's magnitude doesn't change, then that means that the speed doesn't change by definition.
Slightly confusing at 7:10, and at 7:48 to say that the speed of the Sun changes. The speed doesn't change. The acceleration, as correctly stated, is associated with the change of velocity direction and not with the velocity magnitude (aka "speed")
This was a little confusing. Circular orbit = no change in speed over time (only in direction of velocity). Prof Merrifield misspoke a few times calling it change in speed.
No, he didn't. The Sun's orbit isn't circular, so there's a change in speed too.
I can't even concentrate on the video due to the fake equalizer
It's not a "fake" equalizer, it's a real waveform
Okay, but why does the acceleration of the sun influences this stellar aberration that we measured on earth?
My guess is, since the Earth is in the Solar System along with the sun, if the sun is accelerating around the center of the Milky Way so is the earth accelerating around the center of our galaxy?
@@LuisMateusReis Yeah, basically Earth's motion is the sum of two circles - one is tiny, it only takes one year to complete. The other one is galaxy-sized.
Wait, how many pages of that paper is just authors?
Just great.. as if 2020 couldn't get any worse! We now know how fast we're accelerating into a super massive black hole! 😓
I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion. I watched c-beams glitter in the dark near the Tannhauser Gate. All those moments will be lost in time, like tears in rain.
We are adrift in an aethereal sea ... Spinning on a sphere in the Eternal Moment of Creation ... Now. In this motion of space-time, we are bathed in the Energies, Frequencies, and Vibrations of the Light of trillions of stars ... And we all shine on. Reflect on that! 😉
Hi
We will all get to the middle of it all in the end.
Gravity is NOT a force. No energy is needed to 'accelerate' the sun.
Animations feedback: The equalizer graphic is REALLY distracting. The rest of the video is amazing, but those bars are hard to look at.
It's not an equalizer, though.
All I could think of when I saw the thumbnail is the umbrella man from the Kennedy assassination
Zappruder was THE assassin. He has a machinę Gun Hidden in His camera.
As a dilettante of land surveying, the question that comes to mind when watching these astronomy videos is; "what datum are they using?" And what assumptions are used in fixing the datum? Also, more broadly, if the universe is expanding, what point is the universe calculated to be expanding from? Please do not include the word "manifold" in the answer if you have one.
If you're looking for the point, you're missing the point of how expansion works.