We can see things moving faster than light
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- Опубліковано 6 чер 2024
- How is it possible for galaxies and objects in space to move away from us faster than the speed of light? Will we ever see those objects?
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Editor: Levi Butner
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I'm curious: why wasn't the Hubble Sphere called the Hubble Bubble? How much toil and trouble would it be to change the name?
I would think the answer to your question would be self evident.
Your wit is wasted here...
Very good ! 🤣
Easy. Use the correct incantation:
"Presto changeo toil and trouble
Rollo chunky double bubble"
Gary... I love you XD
The concept of light traveling towards us while also moving away from us as space expands reminds me of trying to walk the opposite way on an escalator...although I'm sure it's quite a bit more complicated than that analogy, if I understood anything from this video
just add some acceleration to your walking in the opposite direction since space expands less as you move closer
I used a similar analogy by swimming up a river
@@SoWAHHHT well I guess the deceleration of the escalator as you move down it, would be more accurate
You can walk the opposite way on a escalator by walking faster then the escalator
Thats the flaw with the "Universe is expanding faster then light" thing......light would never reach us from such objects as we wouldnt be stationary in an expanding universes Either (it e 64 billion light years away and a "blank" spot not decernable from empty space)
13.8 billion years would be a late 80's-early 90's Astrophysics/Cosmology/Theology text book......mostly thumped on not actually read (My professors favorite discussion was turning a sack of potatoes into a Universe,never had us open the textbook once, just told us what was in there😶)
@@FrarmerFrank So you're saying this girl is wrong ❔️❓️❔️
I hope you see this, get well soon we miss you!!!!!
Damn I think I actually understood that. It's a bit like a car moving north at 60mph and you jump off south. Even though you jump south, you're still going north. Same thing with the light. It leaves the distant object still moving away from us, but eventually it works it's way to moving toward us at the speed of light
The difference is people can watch and see your jump, regardless how fast is the car moving. ;-)
I think its more like you jumped off when the car was still going 10mph, and by the time you ran back to us, the car was going 60mph, and it was much further away.
@@MrTrevortxeartxe And there's another difference. If the car is moving 10mph North and you jump off going 15mph South, you only have a Southward speed of 5mph the moment you leave the car. If light leaves an object doing lightspeed going 'North', the light travelling 'South' is doing it at lightspeed, no matter the opposite direction of the body it came from.
Nope think about it as the road stretching out, not the car moving. The car moving has no impact on the foton's speed, they always travel lightspeed
Imagine you keep jumping, every jump takes some time T, if during that time the remaining distance has increased by more than your jump distance, you'll never make it. This is creates the dividing line between the observable and unobservable universe.
I wanted to call this series "In here 🧠 Out there 🌿"
I love this series. Something for the brain, something for the eyes and something for the heart ;)
I'm still not clear why you called the path of the light a boomerang motion? I understand the concept of it appearing to stop due to the expansion of space but doesn't a boomerang return to its origin?
"In here brain Out there asparagus"? 😂
@@nadamuchu In this case it isn't that the object (in this case, a photon) is returning to its origin, just that it's sort of turning around.
It starts out moving toward us relative to its origin, but away from us relative to our frame of reference (because the space between us and the photon's emitter is expanding faster than the light is moving through it). Eventually that boundary catches up to the photon, though. When that happens, the space between the photon and Earth is no longer expanding faster than the photon is moving, so it can actually make progress toward reaching Earth. If we could view that photon in real time, we would suddenly see it go from moving very slowly away from us to briefly appearing to stop, to then moving very slowly toward us.
It's a bit like the photon is a person swimming upstream in a powerful current, but the current is getting weaker over time. Initially the stream is too strong, and the person is swept away but over time as they swim the current weakens until eventually the person can overcome the force of the water and start making progress upstream.
Will time get slower if the space is expanded? How would that affect speed of light?
6:05 *"The space between two objects can expand such that it moves those objects apart faster than the speed of light."*
This is perfectly worded. It acknowledges that it _is_ a speed (distance over time) while still highlighting the difference from what we would normally consider a speed.
Kinda like two cars traveling opposite directions at 50 mph each are expanding the distance between them at a rate of 100 mph.
Hey Science Asylum..want a video of yours on this plzz
No object or mass can travel at or faster than the speed of light.
Its Impossible.
It would require all the energy in the universe. That is impossible.
@@codemang87 but, they are not going 100. They are going 50.
Perspective is not speed.
@@rdallas81 indeed. Just like these distant objects appear to be moving faster than the speed of light. They aren't; it just appears so because we are also moving too. You gotta remove our perspective to understand it; hence my car anology.
you explaining top him and awnsering his questions made it way more easy to understand . great teaching technique .
I love everything space related and the way you put it for us not so smart folks is just great! Keep doing what you’re doing.
Ps. How can I steal your editors job?! I would LOVE to learn on the job lol
You can help support her on her Patreon page, shes sick and not doing well you know.
Just imagine the wonders and poetry of deep space . No limitations. As Stephen hawking once said " There should be no boundaries to human endeavor. We are all different. However bad life may seem, there is always something you can do, and succeed at. While there's life, there is hope."
My life has been a complete and total misery ever since Bigfoot stole my precious girlfriend in the middle of the night.😒 He even took all her clothes and the T.V.
And as we all know: "Life... erm... finds a way."
Twitter will someday find this comment to be VERY offensive and you`ll be in big trouble!
During the ad, she says that I probably have a 3M product in arms reach. Since I'm physically at 3M Center (I work here) this is absolutely true.
I looked at my Command Strips and grimaced.
You guys make some great stuff with quality that's hard to beat!
can i get some retroreflector tape? .)
I’m a huge fan of all things science and Physics Girl. She’s a great science communicator and I look forward to watching her career unfold over the coming years. Live long and prosper.
You know her current situation?
This is such a sad comment to see after what happened to her.
This is the best explanation i have ever heard. You make it easier to understand. I miss you. We need you back Dianna so you can teach us more!! Hope your doing well!!
Your editor sounds really smart
Lol
I guess?
Hey! Up and atom I think I learned the similar concept from one of your video. Where you talked about why sky is dark at night despite having so much stars.
Love your channel. One of the best on youtube!
Well he had no clue about the expansion of space time so….
Just when you think you're beginning to understand the universe it humbles you and you've got to rethink everything. Love your videos. Thanks for sharing this knowledge.
I was wondering why is the Universe only expanding outward? Away from each other? Why can't it contract or ossilate or interact so that it orbits each other??
@@justignoreme7725 , I don't think there's anything that says that it can't, only that it isn't. They don't really know why space is expanding. So, they call the force that is causing it, dark energy. Dark because we can't see/tell what it is.
@@NickRoman so is it that we can only measure movement in one direction and that we are incapable of measuring in any other direction or is it we are capable of measuring movement in all directions but can detect movement in one axis??
@@justignoreme7725 No. It's that in whatever direction we look, the universe is expanding; same rate in all directions.
@@timjohnson979 , yes and with the distances we're talking about, I think we really can only measure in one direction. That is, we can't tell if two very distant galaxies are moving laterally with respect to each other. Look into how we know how far away things are to understand that. There are several ways, each depending on how much distance we're talking about. It's an interesting subject and methods get refined over time.
I'm just going to watch your videos again. I've always enjoyed learning from you. Rest as much as you need but please don't quit. I'm sending good vibes your way. ♥
Thanks for the great explanation! Something which always bended my mind. I would love a follow-up, where you explain how during a Big Rip, one of the horizons gets closer until light from even say Andromeda wouldn't reach us anymore, while the observable universe still gets larger as time since the Big Bang increases. I'm still a bit confused about that, how that works.
Mr. Editor: you didn’t give her the slide transition! Awwwww.
We had a good laugh at this. Sometimes we leave things that make us laugh hoping someone else will laugh, but knowing they'll probably just think it's awkward.
@@physicsgirl can we laugh and think it’s awkward? Awkward isn’t necessarily bad :)
@@physicsgirl It was so awkward but cute too. It gives your videos it's own character. It's why we keep coming back to you!! Keep it up, Dianna!!
@@physicsgirl I found it hilarious
He should have given you a more elaborated transition then a slide one.
Fun fact: If the universe was expanding at a constant rate instead of an accelerating rate, then there would be no event horizon; light from every object would eventually reach us. This is called the "ant on the rubber rope" puzzle
Thank you John.
Wouldn't we have a big crunch as well?
@@michaelwachendorf2096
Plausibly yes.
@@michaelwachendorf2096 we should in theory, that is if dark energy decreases over time then gravity will eventually become dominant again
@@michaelwachendorf2096 Not necessarily. Hypothetically, you could balance matter and dark energy so that universe forever expands at a constant rate. I don't know if that'd be a stable equilibrium, but if it was attainable, things would forever recede at superluminal speeds, and from any point and any time, light would _eventually_ reach us. But if the expansion is accelerating, even just a little bit, an event horizon is formed, and that appears to be the real case of our universe.
You are so good at this. Your delivery is so absorbing. Well done
I always liked the example of walking on a travelator (flat escalator). You can only move along the travelator at the speed of light, but the fact that it itself is moving, means the sum total is moving faster away from the start point.
I live in Argentina. My 10 year old daughter loved your video but she relied on my translation to understand it. You should make a channel with a Spanish translator in the audio. You would capture many children and adolescents in these latitudes. You have a great way to spread science. Keep it up.
Closed captioning perhaps?
But UA-cam ... The captioning can be very inaccurate. Much like, say, Google translations are often inaccurate. This is 2022, where's my jetpack? Oh wait, that's right, we can't even get our own spoken words to come out correctly, nevermind something useful like major planet wide languages to be supported here on you tube... Seems what you've had to do, translate it yourself, is about as good as we can do.
I think your idea would serve well the needs of English as second language speakers of the world.
Til then, I'm just gonna wait around til the future gets here... Maybe then, we can work out the kinks of more accessable media options... And jetpacks!
I am currently attending school at south Albany highschool in Oregon, I was told by my physics 2 teacher mrs.Jones that this girl went to the same highschool and was taught by the same instructor. It’s great to know I have such an amazing physics teacher who can mold minds as great as the one we see in this video!
Lovely everything :) Explanations and the whole vibe / setup :)
please get better Diana 😓🥰
Wait, so does that mean that, even if it were possible, we would never be able to see the “edge” of the universe because it’s moving away faster than the speed of light? Or am I misunderstanding?
Yes ua-cam.com/video/eMvQUDAc0zU/v-deo.html
Faxx
Yes, that is correct. Eventually, far far in the future the amount of stuff that we can "see" will actually grow less and less over time because everything is so spread out. Talking like, long after the sun explodes kind of time scale though.
Depends what you mean by the "edge" of the universe. If you're talking about the edge of the theoretically "observable universe," well WHOOEE it gets complicated.
- We can't see that edge because the universe was opaque to light at the very beginning.
- But we can see pretty close (that's the cosmic microwave background light). With the CMB, we're seeing the universe as was about 13.7 billion years ago.
If you're asking about the edge of the WHOLE universe, we don't even know if there is an "edge." But if there were, and it were beyond the observable universe, then we'll never see it as it is now.
As the rest have said..yep. Love it.
Might not even be an edge. One possible model is the Universe is like the surface of an expanding balloon. Not the interior volume where the balloon surface is the edge, but the surface where if you went along far enough, you might circle back like going around a globe.
This has just become my "go-to" method for persuading people that I'm smart.
Great video; clearly explained; with good use of props and diagrams to illustrate potentially confusing concepts.
5 STARS!
Sorry, I couldn't help myself. Granting stars on an astrophysics or cosmology video is empowering.
The smartest person I ever met said little to nothing..., just saying.
It's cool you couldn't help out. You have more important things to do. Like giving birth to Tony :)
Thank you for helping me finally get my head around this really tricky topic!
3M also known as Minnesota Mining and Manufacturing Company. Their products are amazing and as a jewelry artist I use some of them to make my pieces. Love you 3M! Keep doing what you do best.
She’s so passionate about what she is explaining; I love it.
I'd love to go on a hike deep in the woods while getting deep into conversations
Its kind of cringe as well indunno feels like a quirky act
yes! I listen to her cause shes filled with joy when she's teaching it.
Just imagine being at a campfire where she is explaining all this confusing physics stuff
@@ypey1 You're right, it's acting. NOT that she doesn't get it but the channel is a commercial business.
She's so giddy when she talks about things she loves 😍 That's so cool and inspiring!
The Earth flat 🗺
@Eimi Eirene propaganda
Problem is, she is going with an "evolution" viewpoint ( saying universe is "billions" of years old). Scripture tells us God created it during the six days of Creation. So all her "science" is off.
@@jsims1617 Scripture and science has no correlation.
@@jsims1617 problem is, your “scripture” viewpoint is outdated propaganda to keep people placated. please explain how you think the world, the universe, was formed in six days in words other than “invisible sky daddy.”
I love the stuff you talk about u would be fun to figure out things you really get heavy.i have not met to many people who be heavy about a subject keep up the good work 👍❤❤
Wow, that simple and clear explanation is much appreciated. fantastic girl.
5:30 There once was a girl who was bright
She could travel much faster than light
She set off one day, in a relative way
And returned the previous night.
Perhaps the bright girl was Physics Girl.
I love how passionate and excited you are about all of this stuff, it is absolutely infectious and your videos are always a joy to watch.
The Earth is flat! There is no proof that the Earth is round and NASA is an anti religious organisation so don’t listen to them. Even Russian are atheist organisation, so you can’t trust them.
@@anntakamaki1960 The Earth isn't flat--it's concave. We live on the inside of a spheroid and the sky is only an illusion at the center of everything... tfic.
I am so glad to continue to see the physics girl videos. I do hope see is recovering and one day we can rejoice when she is able to put out a new video. Best wishes for a full recovery.
Listening to you and watching your videos are just so captivating
11:02 I find it especially touching that Diana appears to value the camera more than physics demonstrations and, possibly, her editor...
It's great to see your excitement when talking about cosmology , I see it in you and I know how you feel, I am 57 years old and have been into Science, cosmology and space since I was very young after seeing the Moon landings that was the spark for me. It is a lonely subject to be into because in all my years I have had very few deep conversations about cosmology and when you meet someone who wants to listen I just feel like I can't get it all out with the excitement. I still think and watch about cosmology, Science and space every day and am still as excited like you about it all.
seeing is one thing believing is another :)
I was talking to a guy who told me his onewheel had a malfunction causing him to nosedive and crash. I mentioned it could have been caused by a cosmic ray from a quasar or gamma ray burst billions of light years away in the far distant past. The conversation instantly went awkward and quickly ended lol. Your plight must be common.
Ran across this video from a couple years ago. Please recover quickly! Looking forward to your full recovery.
Subscribed. Thanks for these fascinating content.
I ABSOLUTELY LOVE YOU YOUR CONTENT!!!! and so does my granddaughter!!! She’s 5 and we love doing your experiments at home. YOU ROCK!!!
My favorite thing in the world is when old people type on caps on the internet. Its this really weird cultural phenomenon. But like its very pervasive. I wonder if we can track the reason and inception.
@@nominalnostalgia1347 One reason could be eyesight difficulties. Don't let the small things distract you brother.
@@nominalnostalgia1347 With enough counseling/therapy you’ll eventually be able to move forward in your life… it’ll just take some time (lots of time in your case)
@@nominalnostalgia1347 ъеааyeaaaaaaaaaaaaaaaaaa
@@raincheck5892 eeeey that didnt sound nice
I love that sometimes it feels like I'm learning things at the same time as you and that you get as excited about it as I do.
I remember as a young teen when there was still a lot of auguring on whats happening that it came out that space was both shrinking and expanding, depending on the areas, but lately all the videos I'v watched all say its only expanding yet I'v never seen anything about it being wrong either. There was a few different pronounced channels that talked about both side being right, just that its doing both and not one or the other.
Just discovered you.
I will follow you from now🥰
Amazing video
This is the first time ever I hear a physicist saying that engineers are the best scientists. THANKS 3M!
Sheldon Cooper will tear you apart if you do not retract your comment.
That’s true because they solve problems than to believe without prove.
That's because they're a terrible physicist.
@@isaacstone7899 in defense ofPhysicists, they prove with their mathematical computations to back up their theories. As an Engineer myself, i feel insultated whenever Sheldon belittle Engineers... But i like the comedy of the show. Computations and theories are for scientists. Engineers put them to actual.
@@Dylon1981 both are less without the other.
Thereby neither is better.
Discovered your channel recently and can't stop watching all your videos! Your passion and enthusiasm is palpable. And your presentation style is a perfectly unique blend of informative, quirky, and fun. Keep up the great work!
Physics Girl, you are awesome! Thank you for making complex physics understandable. One question, if we are at the center of the observable universe then where is the actual center of the universe and is there anything there if everything is expanding away from that point? Sincerely, Dr. B.
I went to her UA-cam channel a couple days a go and there was a post saying she's dealing with long covid. It bummed me out.
Try PBS spacetime as a companion series
"where is the actual center of the universe"
I don't think anyone knows where the center of the actual universe is, because we don't even know how big the universe is.
Every point is the center and no point I the center. Think of the surface of a ball if the ball expands. The universe is like that
Off course we are at the center of the observable universe, we set the boundary, but due to the vastness of the actual universe there is no centre at all .... And definitely not one we could ever ever find
Think
Tanks for explaining such a difficult concept. Thats as I understood it. Best wishes and waiting for your next video.
Zooms like the one at 0:28 never fail to give me goose bumps. It is astonishing that by simply looking into the depths of the sky we can reconstruct the history of the earth and the whole (expanding) universe. Truly awe-inspiring.
@@youngmom5586 🤬🤬🤬
@@Rick_Cleland it's a spambot, please just report it as spam or explicit content.
@@IanGrams 🤬🤬🤬
@@IanGrams I thought she was trying to represent space expanding so fast between her words that strange, new matter began popping up in our view . . . maybe I’m over-imagining things?
@@JTheMelon er, what? Are you upset I asked someone to report spam?
4:38 The Scotchlite is vastly used in motion capture because MotionCap camera takes profit of this specific property to reflect the light in the opposite direction. that's why they have multiple infrared LED around the camera.
I didn't know that! The retroflection is also all over street signs. I always wondered why they appear rainbowy sometimes, and now I know.
@@physicsgirl Also used as an effect prop in the 1982 movie TRON to make a (real life) helicopter appear computergraphicsy (although it's just referenced as 3M reflective tape). From what I can tell it was the first movie to do so.
@@physicsgirl Copernicus was wrong. You are the center of my universe. According to Newton’s law of universal gravitation, If I’m attracted to you, then you’re attracted to me. I’d really like to study this heavenly body😉😉😍😍😁😁
Thanks for your video!! Great explanation!!
Great work!!!
Discovered this channel today and it has to be the single best channel on all of youtube! I have HOURS ahead of me to catch up.
This format is really great, you should do more of it!
Even though I’m in nursing school right now pursuing my BSN, I love science and more specifically astronomy. The size of the observable universe is truly beyond amazing 🤩
Two things about the universe always get me thinking.. 1st is how small we truly are compared to everything we can see out there.. and 2nd is our place in time, is this 13.4 billion years at the beginning or end of the past 100 trillion years?.. 13.4 billion is such a small number relatively speaking, so where in time are we?. or did time cease to exist before this big bang.. and if so, how long did that last, lol..
@@MH-nc5jd if time had ceased, how could that 'timeless' period last for any period of time?
Hope everything is getting better!!!!
I miss her regular videos. Get well soon physics girl! The world is praying for you
I really like that you speak to the camera man. It's like you are speaking to me directly and most of the time, the camera man is answering what I would say 🙂keep up the good work !
Love your work. It's rare that someone like yourself is charismatic and devoted towards higher learning. Very cool.
You have now answered one of my biggest questions. THANK YOU
"Relative to us" is a critical phrase here. A person could easily fall into the misconception that all these spheres and bubbles and incoming and outgoing arrows of light around us in the center indicates an Earth-centered universe. It's mind-blowing to remember that everything you're saying about the positions and relationships of all parts of the universe, seen and unseen, and how things are moving slower or faster relative to "us," is true starting from any point in the universe--again, seen or unseen by us.
These were the thoughts I was having. We are part of that expansion and the objects we observe could be expanding with us in parallel rather than away from us. It is still good and thought-provoking content.
Thank you!! I've been trying to comprehend this Astronomical stuff for decades...you just explained it in a way I can grasp! I'll watch again several times because I'm getting older & my brain doesn't retain knowledge like it used to...😎
9:20 I've been doing some pondering and thinking of it as velocity rather than displacement makes a lot more sense. The Hubble sphere is moving away faster than the light is moving away. Once the hubble sphere overtakes the photon, then the displacement starts decreasing.
If you're at an opposing side of the Hubble sphere it would appear that the opposite side is moving at twice the speed of light? Everything is relative, so how do we really know how fast anything is moving? We could be moving at a million times the speed of light collectively and never know it.
I now have a pretty good grasp on the concept that everything in space is expanding/accelerating away from everything else in space, but what I don't understand then, is how some galaxies are still merging with other galaxies? i.e.: Isn't The Andromeda Galaxy supposed to be combining with us (The Milky Way Galaxy) in something like three and a half billion years or so? Why isn't Andromeda accelerating away from us like everything else in space is? I can't be the first person to ask this question, but I have never heard an explanation of this seeming 'exception to the expanding universe rule.' I would love for you to do a video explaining these kinds of apparent anomalies as our understanding of our universe continues to grow and mature.
Get well soon
You’re very loved
Thank you for all of the awesome videos
Sometimes I wanna cry feeling how little I know. We feel lucky to get such a mentor like you @Physics Girl.
You probably know more than me about something :)
pay attention in the science and math classes. of course, it could be too late at this point. u must accept indoctrination, which in itself will lower your IQ, before you will be taught some truths. i feel sorry for yall, because the one thing all these commies wont tell you is that there is a Creator. He not only creates, He stretches space. So, knowing that you'll also know that there no such thing as extra-terrestrial visitations, because living things cant cross the firmament..He lets you see very far, but we cant go there.
@@ahoksbergen *cough BS cough*
My brain had a hard time understanding the vastness of our universe.
I love how you genuinely get excited talking about this topic!
Physics Girl - I've got two questions:
Question number 1.
If the escape velocity is a function of distance then how can the light emitted from beyond the Hubble Sphere ever reach the observer? I mean, how can light ever reach the observer if the distance between the observer and the light increases, due to space expansion, faster than light actually travels through space?
Question number 2.
How come the Hubble Sphere is expanding?
I’m watching this again after a year and my head still hurts trying to grasp
Get better!! I miss your videos
And in another mind blowing concept, every object in the universe has it's own "Hubble sphere". All those photons reaching every other galaxy/star system/planet/molecule that make their way into every other "Hubble sphere" will eventually reach those objects. The light wave doesn't change, just the perception of it and its travel time/distance from every view point it seems.
Don't know if that all makes sense.
@gilbert Godfrey, you can have a like just for the last comment you made about the cigar lol
Absolutely brilliant format. Really enjoyed this video!
Physics Girl is mind-expanding! Wishing you well.
The distances involved in this makes it very confounding in practical discourse.
Really well presented in an accessible and understandable way, even if my poor brain was hanging onto comprehension by its fingernails! 🤯Thank you for a great video
Please watch the older version of the cosmos with carl sagan. It has much more neatly packed information bits. This is just 3-4 times telling the same thing over and over to make youtube algo happy.
I have say she explained this terribly, bumerang really? Light's direction never changes rather universe is expanding slower and slower as the light is traveling so it eventually reaches us, it is like swimming against current that there is higher slope at the edge of observable universe so current is very strong. But still it isn't higher than light speed so it keeps traveling up the current and the slope decreases more and more so light travels faster even if the actual speed of light never changes. So even if actual speed difference between Earth and an galaxy at the edge of observeable universe is 3 times higher than light speed there is actually nothing moving faster than light speed rather current becomes longer as it is expanding in every point not just around that galaxy..
Fantastic video, thanks! I think a more complex graphic would have been really helpful in describing the travel of light from beyond the Hubble sphere - my mind is still trying to put it together!
On major flaw with the Hubble Sphere hypothesis, is that earth is in the center of the expansion
A simple concept for the expansion is from shooting at a moving target. Learning to lead your target and estimate the distance involved is a local example of the same process as galactic motion.
Very well put together, Thanks Dianna.
I really enjoy your videos and the fresh look at physics they provide. You're like the 'Taryn Southern' of the physics world.
Much love and positive energy to you!
Such as a flashlight reaching out to the expanse of space the further it goes the light frequency gets stretched out. The further in the light travels the frequency gets stretched out you would actually have to take in consideration of the stretch out and have that into the equation to when the light frequency is originally starts to where it gets to its distance
I've seen so many videos on this topic. And it still melts my mind
I appreciate this video a lot. When I think of the light of stars and galaxies taking so long to reach us, so long that they may no longer be here, it sometimes feels like looking at the ghosts of the universe.
It makes me kinda sad. Theoretically we could see those galaxies and stars but never know much about it. If that galaxy contained life we'd never know, and to other galaxies that far away our fate will eventually be the same. If there's life out all the way out there, either now our billions of years from now, we would never know each other existed.
Dianna, my 10 yr old son and I love your channel. I was always told that objects could not travel faster than the speed of light. I often argued this point with my physics prof (MANY years ago). I said, if the universe is expanding at the speed of light, doesn’t that mean that objects on the opposite side of the universe center are then expanding away from each other at twice this speed of light? Would you consider doing a video discussing the topic of the speed of light and how objects can travel faster than it, and what it means to the objects in our universe? Thanks!!
Still true, nothing exceeds the speed of light. And space doesn’t expand at the “speed of light”. It expands at a fixed speed per fixed distance, but it’s “cumulative”, that’s why things further away appear to be getting away faster.
But still nothing moves in space faster than light, there is no argument around it
@@HeliBenj That is the video she does did! She explained that it is not the objects that are moving faster the speed of light, but the universe itself within which they object is moving, that is moving faster than the speed of light. I thought she explained this very well. Still a difficult concept to gets one's head around.
I followed till expanding universe and hubble sphere/expansion, but when she explains light initially moving away from us and then entering back hubble sphere broke my head lol, well she assured us it doesn't make sense ha ha, so that's there. Love her videos, I hope she sees a speedy recovery. We need more content creators like this.
For the light that moves away from us and then back toward us, I'm imagining photons running at a constant speed on a treadmill that slows down over time.
I've wondered this, thanks for explaining in greater detail than my thought!
The way I understand this concept based on your explanation is that every point in space is the center of its own Hubble sphere, & some galaxies outside of our Hubble sphere have a Hubble sphere that overlaps ours. So although a galaxy itself may be moving away from us at the speed of light, its own light can reach our Hubble sphere, since the perimeter of our sphere is within its sphere; at which point we have the possibility of receiving that light.
Please get better. Please come back.
What
@@michaelcangelosi1684 You need clarification?
You're amazing! I can't get enough of your content.
I love it when you blow my mind. Going to have to watch this again but it’s filled with fascinating concepts.
Physics Girl, your video made me ponder, not only my lack of knowledge about science but also this topic about objects far away moving even further away from us at the speed of light. A question occurred to me.
We say that the universe is expanding. Yet, clearly, not EVERYTHING in space, the things that are somewhat close to us, is expanding away from us. For example, if Alpha Centauri was flying away from our solar system at the speed of light, I’m sure I would have heard about it. So, why isn't it?
That begs the question: does that means that there’s some sort of demarcation line, a precise distance away where all matter beyond it is travelling away from us? But if you moved a foot closer to us from this line, matter would stay where it is and our relative positions would be stable?
This stuff makes my head ache.
Thanks,
Scott
Gahanna, Ohio
What this example is missing, relativistic time dilation. We might know that the distance the light travelled was 30+ billion lightyears and the light started the journey 13.4 billion years ago relative to us... But at lightspeed, that distance would be instant (at perspective of that light).
If we could travel at the speed of light, any distance would be instant. Closer the speed of light you'll travel, less time goes forward relative to others. It's possible to travel interstellar distances in a short amount of time, but you would need to travel at massive speed.
It might have taken over 13 billion years from some old light from a galaxy/star/explosion to hit our telescope, but it didn't take that time to travel here. Relativistic time dilation is just so facinating and weird.
Light cannot travel over a light year away instantly. That's why it's called a lightyear. "Time it takes light to travel in a year."
And it did take the light that long to travel here. Everything we see a lightyear away we see it as it was a year ago. That's why when we see a distant super nova that super nova is actually already done and over with. If we see a super nova "Happening" 30 billion light years away. If you instantly teleported to that spot that super nova would have already ben done and finished. But earth would still be seeing it. Even astrologists say the same thing.
@@mrwang420 Maybe you should learn more about relativistic time dilation from Einsteins theory of special relativity. There's no scientist that have yet disproved his theory. Light doesn’t experience time at all.
@@mrwang420 Also, one more thing with relativistic time dilation. We on earth can easily test the speed of light, and get real light speed values. But we still have to adjust time/atomic clocks even when using the GPS system. This is because GPS satellites travel at higher relative speed than people on earth. The faster something goes, time slows down relative to the observer. If I could travel one year at 99.99% speed of light, in my perspective, the trip would last one year. When I came back, 70 years would have passed for others on earth.
Moving at different velocities or located in different regions of a gravitational field, time ticks at different rates. Light speed is the limit when any distance would be instant.
Signed my kids up for STEM classes and we had so much fun making chemical clocks and elephant toothpaste last weekend. Can't wait for the next one. I love seeing the excitement in my kid's eyes when they get their kits in the mail.
Thanks for doing stuff like this for your kids. My parents did the same thing and it's part of the reason why I'm pursuing a career in physics.
How do you sign up for this and how much does it cost? I'm on a budget bUt my daughter and I enjoy home projects so depending on how expensive it is I will find a way lol.
We watched videos on elephant toothpaste and she loves it. If I make one more bowl of slime I will go crazy.
I do like the video and your presentation. It's truly down to earth. I remember when I was young of hearing that 60 miles an hour was the limit to the speed man to travel. If someone could travel faster than 60 MPH they wouldn't be able to breathe the air. It seems that man has been breaking barriers as long as we've been conscious. Thank You for giving me more to think about than I had before. Imagination is the key to all things.
Thank you! This is a decent explanation why the Hubble sphere is NOT a horizon, although you could have used a slightly more accurate figure of 14.5Gly (z=1.48).
However, @11:12 Gravity does NOT overcome the expansion of space. There is not tug-of-war between gravity and expansion. Space simply does NOT expand where it is curved (described by a metric other than the FLRW). The cosmological constant (expansion) is contained only in the FLRW metric which describes flat spacetime.
It's s matter of definitions: for starts there is the cosmic speed limit which refers to the maximal velocity objects can move in regular space and absolute vacuum. Light is one example of a boson that can move in this velocity through space due to zero rest mass.
The space continuum itself expands so you get galaxies that are moving fast away from us "faster than the cosmic speed limit". It's still maintaining the principle of relativity that nothing can surpass the cosmic speed limit.
Love this format. Very smart for building emotional connection!
Thank you. You really did explain this well, much better than most, not to take anything away from all the other great content creators. Mind blown.
When people talk about space itself expanding, I feel there's always something missing from the explanation and I'm left with further questions.
Let's start with the basic point: is space, as in the vacuum itself, regarded as made up of something? Of units of something? Is it imagined there is some sort of a "vacuum particle"?
And in case that is the case, then what is suggested to occur during its expansion? Are the units of space multiplying or just getting further away from one another? Because if it's the second option, why would that even be perceptual to us or to our instruments, considering that only points of actual space should be able to occupy matter and energy, and thus points of "space between the space"-a no-space of sorts-should have no effect on the incoming light that doesn't actually interact with them - because there's nothing to interact with?
Unless there's a third option, the belief that two points of space getting further away from each other indeed _won't_ allow light to actually occupy any new point in-between them, but that an increasing (or decreasing for that matter) distance _does_ change the (*relative) time it takes a photon to proceed from one "space particle" to another?
_*Relative_ of course referring to the fact that if such phenomenon does actually exist, its effect should only be perceptible when looking at light coming through mediums of space-densities different to ours, as space within a locality being scaled up or down possibly scales all local physics in a way that keeps perception parallel.
I hark back to my physics class - 50 years ago. My physics instructor asked us - move relative to what? At 3:46 it says that 97% of the objects are moving away from us. Does that make us the center of the universe? What would the Catholic Church and Copernicus say about that? My physics class was long ago, but Copernicus was NOT a personal acquaintance.
As we look all the way back to the beginning (big bang), shouldn’t we be able to look any other direction and see the “other side” of it? Which would be exactly the same thing? I guess I’m saying that any direction we look all the way to the “edge of the universe = the Big Bang,” wouldn’t it all look the same?
I saw Destin’s visit. May God bless you on your path to recovery.