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 wanted to call this series "In here 🧠 Out there 🌿"

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

Listening to you and watching your videos are just so captivating

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

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 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 explaining top him and awnsering his questions made it way more easy to understand . great teaching technique .

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.

Your editor sounds really smart

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.

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.

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."

Mr. Editor: you didn’t give her the slide transition! Awwwww.

You are so good at this. Your delivery is so absorbing. Well done

Very clear and truly astonishing! thanks so much for helping us understand more.

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 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.

Thank you for helping me finally get my head around this really tricky topic!

Ran across this video from a couple years ago. Please recover quickly! Looking forward to your full recovery.

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!

She's so giddy when she talks about things she loves 😍 That's so cool and inspiring!

Thanks for your video!! Great explanation!! Great work!!!

For the first time in my KZfaq activity, I watched a sponsor time in its entirety! That new 3M tape is actually pretty awesome! About the video itself, amazing content as always! Mind-bending science always amazes me! Thank you!

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?

She’s so passionate about what she is explaining; I love it.

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. ♥

Wow, You just made the LED light in my head go on! Thank you Physics Girl. You helped me understand the relationship between observed distance based on light speed travel time and the adjusted distance based on the expansion! Cool video! (Yes, 6 months late in responding but I just discovered you on KZfaq). Catching up. (I think I may understand that Cosmic Event Horizon now: The Hubble Sphere is like a faster “shock wave” overtaking the slower “shock wave” of the CEH yet never catching up with it, yielding the effect of light in the CEH appearing to move away initially but eventually appearing to move towards us? Is that a change in the red shift? Or am I way off the mark?

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.

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

This is the first time I've come across one of your videos and I'm loving your enthusiasm here

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 👍❤❤

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.

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.

Lovely everything :) Explanations and the whole vibe / setup :)

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.

This is the first time ever I hear a physicist saying that engineers are the best scientists. THANKS 3M!

11:02 I find it especially touching that Diana appears to value the camera more than physics demonstrations and, possibly, her editor...

Hope everything is getting better!!!!

Much love and positive energy to you!

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.

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 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 recently found you, and i love love love your videos!

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.

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.

These explanations are amazing..how can you not fall in love with the science..

Tanks for explaining such a difficult concept. Thats as I understood it. Best wishes and waiting for your next video.

I ABSOLUTELY LOVE YOU YOUR CONTENT!!!! and so does my granddaughter!!! She’s 5 and we love doing your experiments at home. YOU ROCK!!!

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!

Does each planet in the universe have its own hubble sphere? In other words, if we were on a distant planet outside of Earth's Hubble sphere, would Earth appear to be the one that was moving away faster than the speed of light?

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.

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 !

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.

Just discovered you. I will follow you from now🥰 Amazing video

Get well soon You’re very loved Thank you for all of the awesome videos

Besides having 3m products within arm's reach, all of us have some 3m products inside our bodies. Forever. Thanks Dupont!

This format is really great, you should do more of it!

"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.

I like the way you explain science concepts Physics Girl. I like it very much

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!

I've seen so many videos on this topic. And it still melts my mind

Seriously LOVE the way you explain these things! It makes sense that galaxies are moving through space but I have never understood the concept of ‘space itself is expanding’. How does that work? And how can I ever have a sealed container if the space within it is what is supposed to be expanding? I wish I could have lunch with you to pick your brain! When you are looking into space and see reflections and distortions caused by gravitational lensing, how do you know what is real and what is a reflection? Some of the images from Hubble that show gravitational lensing seem to have near symmetry, but lensing makes it difficult to know, when just looking at the images. Could/does gravitational lensing cause us to misunderstand what we are seeing so much so that we conclude that everything is moving away at an increasing rate and almost everything is morning ‘away’ so even the fabric of space must be expanding? Or is there possibly a large ‘lens’ (maybe due to the sun, galactic center, dark matter, etc.) see is reflection of reality? Just like when a car drives by a distorted window and the image gets stretched out and quickly wraps around the arc of the distortion in the glass…Hypothetically, if some of the galaxies we see are reflections like I mention above, how does that change our perception of doppler shift? Ok ok maybeeee 12 lunches =]

I miss her regular videos. Get well soon physics girl! The world is praying for you

I've wondered this, thanks for explaining in greater detail than my thought!

Absolutely brilliant format. Really enjoyed this video!

You explain things very digestively easy to fall keep it looking great work thank you

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.

I wish I had nerdy friends like this to hike with while talking about crazy physics.

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

I'm not a physist so . But I listen to all the big names in this field and this mind blower is new to me. My humble point is I didn't know this and thanks for bringing it to my attention. Awsome,, Alex kowaliuk from America 🇺🇸 👌

This is a very informative episode. It caused me to question the calculations of time and space. The missing ingredient as it relates light and time is an equation called "The Inverse Square law of Light". Which is explained as: Light intensity decreases with distance from source to receiving surface (sink), and the rate of decrease is in proportion to the square of the distance between emitter and receiver. This is called the Inverse Square Law. How do you think this has an effect on the entire question?

I really enjoy your videos and the fresh look at physics they provide. You're like the 'Taryn Southern' of the physics world.

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...😎

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.

0:54 , my take: The 'universe' is a giant explosion; everything is in constant fluctuation, nothing is stagnant. the light that started moving towards us X billion years ago, carrying an image of what it had bounced off of (which is crazy, if you think about it.) might be reaching us now; but whatever it is showing us, has moved, since then (relatively - since the universe is in expansion. - it may have stayed 'in orbit' during that time. ) - and has been doing so for the same number of years the light we see has been travelling. (An aside thought; if the space between two objects expands, is that any different from them carrying a velocity that moved them 'apart'? - and if it was, could you tell? ... Curious.)

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.

Sometimes I wanna cry feeling how little I know. We feel lucky to get such a mentor like you @Physics Girl.

This is more easily understood with the classic from the General Theory of Relativity: “Space-time tells matter how to move; matter tells space-time how to curve”.

Go girl like your video so much makes alot of sense

Very well put together, Thanks Dianna.

Love your work. It's rare that someone like yourself is charismatic and devoted towards higher learning. Very cool.

I am an old person ... the fact that you are in love is so great that makes all your information greater ... go girl!

I’m watching this again after a year and my head still hurts trying to grasp Get better!! I miss your videos

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 🤩

I love it when you blow my mind. Going to have to watch this again but it’s filled with fascinating concepts.

Here’s a question for you. Is there a fixed amount of matter in universe? If matter is expanding at a speed of x, then aren’t we also moving at a speed of x? Or, if there was a big bang, a point from which everything started moving away from one another then how is anything moving faster than light? Isn’t it just somethings, relative to earth, are moving directly away from us, somethings move with us and some things move at an angle from us. But everything should either be moving at the same “bang” rate- of-speed or something has to account for why some matter moves faster or lower than other matter and why matter expanding further and further apart is either doing so at a constant, slower or faster rate? Is something pulling it or restricting it or in an empty vacuum does it move effortlessly at a constant rate forever?

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.

My brain had a hard time understanding the vastness of our universe. I love how you genuinely get excited talking about this topic!

Love this format. Very smart for building emotional connection!

I wish YOU'D been my h/s science teacher. Thx for presenting the facts in an ez to follow format

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.

You're amazing! I can't get enough of your content.

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.

Diana, Your videos are precious as are you. I hope your health is improving.

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

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.

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.

this is so amazing and mind blowing

"Turns out the universe was bigger than we thought" That's my quote for today. You blow my mind everytime I listen to you. All I need to know about the universe is that I am the center of it all 😋