What Does Dark Energy Really Do?

Рет қаралды 1,017,590

8 жыл бұрын

Dark energy, what exactly does it do? Find out in this episode of Space Time! Part 3 in our Dark Energy series.
Part 1: • Will the Universe Expa...
Part 2: • Why the Universe Needs...
____________________________________________________________
Get your own Space Time tshirt at bit.ly/1QlzoBi
Tweet at us! @pbsspacetime
Facebook: pbsspacetime
Email us! pbsspacetime [at] gmail [dot] com
Comment on Reddit: / pbsspacetime
Support us on Patreon! / pbsspacetime
Help translate our videos! kzfaq.info_cs_p...
How does dark energy affect the universe's expansion? Measuring past expansion history should tell us the future expansion without ever having to count any galaxies. To measure this we need to measure the redshift-distance relationship, which we will talk about in detail in this episode.
Written and hosted by Matt O’Dowd
Made by Kornhaber Brown (www.kornhaberbrown.com)
Comments
Pravar Parekh
• Why the Universe Needs...
Yeshwanth Vejendla
• Why the Universe Needs...
Thomas Waclav (Ceasar)
• Why the Universe Needs...
Austin Pinheiro
• Why the Universe Needs...
____________________________________________________________
White dwarf supernova simulation from "Three-Dimensional Simulations of the Deflagration Phase of the Gravitationally Confined Detonation Model of Type Ia Supernovae", Jordan et al., 2007, arxiv.org/abs/astro-ph/0703573
Supernova Cosmology Project: Perlmutter et al. 1999, arxiv.org/abs/astro-ph/9812133
High-Z Supernova Search Team: Riess et al. 1998, arxiv.org/abs/astro-ph/9805201

Пікірлер: 1 800

@pgoconn 8 жыл бұрын

"Thanks to you for being honest about the strength of the evidence behind your belief structure." Beautiful.

@Alkaloid-Odin 8 жыл бұрын

lol right

@kefkaZZZ 5 жыл бұрын

I would give you a like but... 69 upvotes - Nice!

@CautiousMeat 8 жыл бұрын

This is the greatest science show ever. Everything on here goes way over my head, but that's why I like it. I have to re-watch these videos to understand them. Thank you for not simplifying everything just to cater to the average person.

@Asimovum 8 жыл бұрын

This guy could convince me that i'm actually a carrot

8 жыл бұрын

+Asimovum Well, the science community needs more credit than most people give it. It is a lot easier to convince people of something when you have a lot of evidence. :-) He does do an awesome job of explaining things for lay-people, though.

@donfox1036 6 жыл бұрын

Asimovum Are u a carrot?

@brendanotoole5871 6 жыл бұрын

kzfaq.info/get/bejne/bNt7Zbp-yJ-waJc.html

@jamesbrown7347 6 жыл бұрын

Goku, is that you?

@thehellyousay 5 жыл бұрын

technically speaking, the differences betwixt you and a carrot are nearly negligible, although cabbages are probably more closely related...

@AndrewK209 8 жыл бұрын

I don't understand any of this, and yet, I still watch.

@mac5794 8 жыл бұрын

ah it's just them metaphors, don't take em seriously

@hephaestus1956 8 жыл бұрын

+Andrew Krause You're not alone.

@ILoveBluePeople 5 жыл бұрын

40% Don't understand... 50% misunderstand and come up with wild theories of their own... and 10% actually understand...

@michaelsouthard2181 5 жыл бұрын

@@ILoveBluePeople And some of that 10% only understand partially, at various degrees.

@noifurze6397 5 жыл бұрын

John Tobin I think that's most of us lol

@izvarzone 8 жыл бұрын

In old times it was called Universe Expansion Now its called Universe DLC

@deadbyte8086 8 жыл бұрын

Lol

@kennethpryde966 8 жыл бұрын

+izvarzone Next the universe will go free to play, but have micro transactions that act as a paywall if you wan to get off your planet.

@deadbyte8086 8 жыл бұрын

+Kenneth Pryde so, the universe will be pay to win

@ryanriverside 8 жыл бұрын

+King Chuck Isn't it, though?

@chrisv4496 8 жыл бұрын

+King Chuck Will be? Pretty sure it already is.

@youduntknowmyname 8 жыл бұрын

If I ever do an astrophysics course I know where to get my summaries.

@Algebrodadio 8 жыл бұрын

Thank you +PBS Space Time for making GR accessible to a general audience.

@GuyWithAnAmazingHat 8 жыл бұрын

I hear people get notifications for new uploads, but nope not me, I do it the old school way, I refresh my subscriptions non stop. And seeing an episode of Space Time is the most delightful thing for me.

@bobdude5282 8 жыл бұрын

If you go to the pbs spacetime account on a mobile device and click on the bell icon you should get notifications.

@NikolasHonnef 8 жыл бұрын

+GuyWithAnAmazingHat You can click on the cogwheel next to the subscribe button to activate notifications.

@DefinedEdits 8 жыл бұрын

When playstation exists but I spend my free time watching videos on theoretical physics.

@firelow 8 жыл бұрын

nerd.

@aemonge88 8 жыл бұрын

+William Pereira Gomes I didn't got the joke ........

@spams9359 8 жыл бұрын

+Defined Edits When sociology final exists, but I spend my time watching videos on theoretical physics.

@aemonge88 8 жыл бұрын

lol, ok. I think I've got it. Thanks Beefy

@TheRealHelvetica 8 жыл бұрын

+Defined Edits I don't blame you the Playstation has no games.

@Robot_Overlord 8 жыл бұрын

simply ..... a great series. keep them coming.

@symbioticcoherence8435 8 жыл бұрын

If there is a company called Apple, there can be a company called Peanut Butter Sandwich Digital Studios.

@prabhchahal4492 8 жыл бұрын

Nice try there coherence

@symbioticcoherence8435 8 жыл бұрын

Prabh Chahal thx :)

@AustinPinheiro_uniquetexthere 8 жыл бұрын

one day in the future there will

@SonicRooncoPrime 8 жыл бұрын

Another excellent video from Peanut Butter Sandwich Digital Studios.

@coquio 8 жыл бұрын

Is it me, or are Mathew's shirts getting tighter with every episode?

@GENIUSAMI100 8 жыл бұрын

+Alfalfa Male Actually he is getting bigger through workouts n supplements

@MaDrung 8 жыл бұрын

+Amitesh Singh Exactly. He is nearing exponential growth.

@GENIUSAMI100 8 жыл бұрын

haha Mathew^x is an ever increasing function..

@pbsspacetime 8 жыл бұрын

+MaDrung Turns out that the effect dark energy and cheeseburgers are both well described by a positive cosmological constant.

@coquio 8 жыл бұрын

+PBS Space Time Curious since there is evidence to suggest that cheeseburgers have actually shrunk in size over time, as demonstrated here. i.imgur.com/bRXrFk2.jpg I hereby declare your theory peer reviewed. -drops mic-

@EugeneKhutoryansky 8 жыл бұрын

My view is that "dark energy" in General Relativity will turn out to be analogous to the precession of the planet Mercury in Newtonian physics. That is, it is an indication that our present model for the fundamental laws of physics is incomplete, and that the true nature of the Universe is far more mysterious and remarkable than we had ever previously imagined.

@ogs_Boga1900 8 жыл бұрын

+Physics Videos by Eugene Khutoryansky i bet it has something to do with infinte states all occuring at the same time. but this might be hogwash

@garethdean6382 8 жыл бұрын

+Physics Videos by Eugene Khutoryansky And, quite likely, relativity will still stand up well enough to be a useful theory a century after its dethroning.

@kindlin 6 жыл бұрын

Just like how we still newtonian mechanics to send spaceships through space.

@Dee-nonamnamrson8718 6 жыл бұрын

Melchior Magni I had a physics teacher that was working on a theory that could have fixed the problem, according to him. He believed the expansion of the universe was the constant and light stands still. It appears to be traveling at the speed of light because we were expanding to it at the speed of light.

@KenMabie 6 жыл бұрын

i think the universe started out as a black hole and that due to hawking radiation it is evaporating off and the less mass it has the faster it radiates .. this is why primordial black holes can only last seconds and stellar mass black holes can last eons and super massive black holes can last eternities ... i mean think about it .. if the universe is expanding .. what is is expanding into? space itself is expanding stretching light causing red shift so space can not be expanding into itself .. so therefore it must be expanding into something whether that something be nothingness itself or the void or what ever .. black holes radiate out into space so what is space itself radiating out into?

@GFJDean35 8 жыл бұрын

I hate that I have to wait a week after the cliffhanger of each episode! Someone needs to throw money at this channel so they can release such good content more than once a week.

@kennethpryde966 8 жыл бұрын

+GFJDean35 Or put it on Netflix so we can binge watch.

@MrMakae90 8 жыл бұрын

I'm in love with this channel.

@MrMayur1210 8 жыл бұрын

Are you love? Hello love, I am mayur. Nice to meet you.

@sam08g16 8 жыл бұрын

+mayur Shah be more respectful with Mr. With This Channel

@LuisSierra42 3 жыл бұрын

@@sam08g16 No

@RockBandRS 8 жыл бұрын

Listening to science in your accent is so relaxing.

@avi_mukesh 8 жыл бұрын

One day... One day I'll be able to understand everything on this channel (I hope :/)...

@travischance5332 8 жыл бұрын

+Tech A.M As long as your passion for it sticks, you can keep moving forward.

@fivish 5 жыл бұрын

When you understand what he is saying it will dawn on you that none of it can be true.

@blakemccreery864 4 жыл бұрын

John King you don’t get it yet then

@winter32842 8 жыл бұрын

I hope you guys win the Webby award. I voted for you guys.

@diurdi 8 жыл бұрын

These episodes just keep on getting better. Having some math together with the intuitive explanation makes it much easier to understand - and remember.

@stevenbain8798 8 жыл бұрын

Still my favorite channel!! Thank you for sharing!!

@CarBENbased 8 жыл бұрын

"Thanks to you for being honest about the strength of the evidence behind your belief structure" Oh snap, shots fired! lol

@nuaw 8 жыл бұрын

I really love your videos! I am an undergraduate student of physics in Venezuela and your videos inspire me every week to study more and more about the misteries of our universe. Keep doing this great job!

@Andy-cn1cu 8 жыл бұрын

Hi guys! I am from Argentina ( Sorry if my English is rusty). I always watch your videos and i think that the effort and quality you put on each one is amazing. You seem to be brilliant people in every aspect, direction, visuals, accurate science topics ha! Congratulations to all of you and thank you for bringing to us this amazing show!

@disculpa 8 жыл бұрын

favorite channel on KZfaq. love the videos!!!

@merkovomerk6802 8 жыл бұрын

Great video as usual. You guys deserve way more subscribers, your content is amazing, and interesting.

@Nehmo 8 жыл бұрын

+Merkovo Merk -- Half a million subs' in April 2016 about, mostly of the English speaking. Considering how important the subject is, that is low. Some people will disagree on the importance, but they simply are wrong. Lot at another way. We are the only ones who know what's happening!

@emsmamma 8 жыл бұрын

I totally agree, I was just looking at the number of subscribers myself and was puzzled by how few there are...very strange.

@ernest7301 8 жыл бұрын

These shows are perfect for napping - I drift away in 1 minute.

@unvergebeneid 8 жыл бұрын

1:41 Oh that must be those panspermia I've been hearing about!

@VideoDroidORG 8 жыл бұрын

+Penny Lane thanks for sharing your vocal cavalry. If i heard one more Tranns and Sperm story this year i would have to firewall Cait Jenner. many terrific articles learned upon a www.google.com/search?q=panspermia

@adamtaylor1739 8 жыл бұрын

Your hair is like a luscious lions mane

@l3ete1geuse 8 жыл бұрын

Can't get enough of this channel. :)

@ItohKuni 8 жыл бұрын

Man, your videos are always REALLY fun and exciting to listen to and watch. Love it every time you guys upload something new. It's also really awesome to see things I've always been interested in like space and time and stars presented in such a fun way :) Keep up the great work guys!

@GusSchultz 8 жыл бұрын

That last line was savage. I love this show so much. When are we going to get a Space Time road show so we can come out and see you give a presentation live?

@GreyFang9 8 жыл бұрын

mmm...I'm going with *P* izza *B* ased *S* cience. All knowledge can be teased out over a hot slice!

@garethdean6382 8 жыл бұрын

+GreyFang9 And pizzas are flat... Whoah.

@GamesFromSpace 8 жыл бұрын

I feel like this series must be sponsored by dark energy, because it keeps expanding longer than anyone would expect.

@smolboyi 8 жыл бұрын

this is my favorite KZfaq show, please continue making videos for the rest of space-time

@NickRoman 8 жыл бұрын

Thanks for giving me this great entertaining (through being informing) show every Wednesday. I always look forward to it.

@Sleepy.Time. 8 жыл бұрын

this channel is outstanding

@Ishn01 8 жыл бұрын

This channel is awesome, and I appreciate all that you guys do to edutain me. Can you explain Milgrom’s Modified Newtonian Dynamics and how it applies to the topic you've been discussing for the past few weeks?

@halulife35 8 жыл бұрын

love the show btw. been watching for months and always look forward to the next one

@uniphobia 8 жыл бұрын

I'm such a big fan of your show! Keep it coming Professor!

@pokoirlyase5931 8 жыл бұрын

Awesome as always

@StephenGillie 8 жыл бұрын

Redshifting is a loss of energy of a photon. As the photon moves through space, it slowly loses energy to the expansion of the universe over time. Which is odd, because photons don't experience time, since they move at light speed. This coupled with the concept that the universe is just World Lines in 4D Spacetime, and time is an illusion begs the question of how the universe is expanding over time, if time is just an illusion. Is the 4D Spacetime larger at one end than the other? Or is this just a conceptual illusion like the Observable Universe?

@Exascale 8 жыл бұрын

The loss of energy of the photons is what is causing the universe to accelerate. Eventually the red shift of everything gets so extreme and at some point everything is deep redshifted photons. These photons eventually redshift until their wavelength is the size of the universe. That is the singular vibration that starts the next universe.

@StephenGillie 8 жыл бұрын

That would have been a lot easier back when the universe was the size of a grain of rice.

@tonywells7512 8 жыл бұрын

Loss of energy of photons has nothing to do with universal acceleration. The energy of CMB photons (and the total energy of all photons in the universe) is tiny in comparison.

@docstomp5524 8 жыл бұрын

Isn't the redshift in the spectrum caused be the observed object moving away relative to observer? I've never heard of another explanation for the cause

@StephenGillie 8 жыл бұрын

@steadric 7 жыл бұрын

Really enjoying this playlist, thanks for the amazing content and quality!!

@renatodavalos1439 8 жыл бұрын

I love that you have been introducing math for physics dummies like myself. Great show, great explanations.

@jarodtall7876 8 жыл бұрын

He just roasted religion with his final comment. Classic stuff.

@TheCosmosWins 8 жыл бұрын

+Jarod Tall he sure did lmao

@poketopa1234 8 жыл бұрын

+Jarod Tall Kinda uncalled for tho

@cristianvargas7112 8 жыл бұрын

+Jarod Tall was fucking savage lol

@spams9359 8 жыл бұрын

+Jarod Tall No chill

@darknrg3174 6 жыл бұрын

the LORD moves in mysterious ways hehe

@gasdive 8 жыл бұрын

I was actually eating a peanut butter sandwich when I watched this. From my sample size of one, I can easily conclude that mysterious forces are at work. Well I would except that significance contains the term n-1

@rebelScience 8 жыл бұрын

I love that cool retro video filter you have in this video.

@chriskelly6574 2 жыл бұрын

I think you are rather slick. Both you and Sabine. Keep up the great work and thanks for taking the time.

@ewanhassall7350 8 жыл бұрын

Can't decide whether that was a dis on religion. 12:23

@sweetjaysus4507 8 жыл бұрын

+ewan hassall oh it was ,it was subtle but respective enough i think

@Vanukass 8 жыл бұрын

+ewan hassall I hope it was. T'was brilliant.

@just_ed4794 8 жыл бұрын

yup

@AMW1able 8 жыл бұрын

+ewan hassall absolutely, and done so craftily the religious dimwits wouldn't pick up on it. No danger of that as they wouldn't watch these videos anyway

@PyrrhoVonHyperborea 8 жыл бұрын

+ewan hassall Religion needs no diss; it's already a massive diss on itself. It's merely coincidence, that the diss above and the self-diss that is religion, coincide... It's like throwing a punch in the air, and some random moron - out of the blue - jumps in front of it, to catch it with his face; that's no fault of the fist, is it?

@EdouardOlszewski 8 жыл бұрын

Is the "Vacuum energy" you mentioned around 7:40 anyhow related to the Casimir effect? It seems to talk about something somehow similar...

@pbsspacetime 8 жыл бұрын

+Edouard Olszewski It MAY be related. The Casimir Effect results from a the zero-point energy of quantized elementary fields. The virtual particles constituting those fields don't "fit" between very close conductive plates. When you try to make the quantum zero-point energy work for dark energy you actually get a bit too much dark energy. 120 orders of magnitude too much! So there's definitely something wrong there, and when theorists understand the normalization problem, this may still be a contender.

@frankschneider6156 8 жыл бұрын

+Edouard Olszewski The casimir effect results from continuous creation of virtual matter-anti matter pairs and is a quantum mechanical attribute of space, while dark energy is a relativistic attribute of space resulting in the expansion of the universe, so something completely different. BUT .... I never thought of this before, but as both seem to be attributes of space itself I wouldn't bet that there is no connection at all.

@iprimoonanollie2598 8 жыл бұрын

+PBS Space Time I'm not sure if you're ever gonna read this comment, but I saw that response, and it's way easier to hear you speak then you writing lol, write in English lol

@198EE4 8 жыл бұрын

My thought as well. Will be interested to see if there is any relation. What an exciting time to live in that we get to search for answers that, until recently, no one even knew were questions.

@gavinkemp7920 8 жыл бұрын

+Edouard Olszewski actually i think the casimir effect is linked more to dark matter. nasa is studying the effect to see if i can be used for a form of warp drive

@jbdds.9727 3 жыл бұрын

I love that PBS Space Time actually gives you good cosmology instead of most "space shows" on TV that are basically geared towards first-graders

@atlantisvelforening 3 ай бұрын

I can hardly express my gratitude for this channel 😊

@ameetdmello2525 8 жыл бұрын

Was dark energy present before the big bang or is it the attribute of the existing universe? could it be integrated with the other fundamental forces as a fifth force? if it is created with the current universe would it be possible that it is negative in nature and can cancel out the potential energy stored in e=mc2 type of energy? Matt i need to know how can we balance the equation to get "absolute nothing" (the logical point/ movement of beginning)?

@hamzawaheed2625 8 жыл бұрын

The awkward moment u realize the first question was from "Trafalgar D Law" xD

@JosefHabdank 8 жыл бұрын

amazing video, packed with deep knowledge. thousands thanks!

@rogerdiogo6893 6 жыл бұрын

I like this guy, the only one on KZfaq that does not confuse "dark matter" with "dark energy".

@TheNeilDarby 8 жыл бұрын

I AM A BRAIN IN SPACE ON THE INTERNET.

@japooskas 5 жыл бұрын

@Joseph K but if a particular brain thinks itself unique, it is.. no matter what constraints or illusions leads to it doing so.

@Eassstt 8 жыл бұрын

+PBS Space Time Is it possible for you guys to give us the titles of the background tracks? You got some awesome study-viable music right there!

@nachannachle2706 6 жыл бұрын

This is BY FAR the most challenging episode of the Space Time series I've watched. It is so technical in content and so compact in delivery. I need to sleep on it to make sense of the details. Dark energy seems to be the new hot item in Physics. I can already tell that in 20 years or so we will have to completely review key concepts such as "redshift", "expansion" and "cosmological distances": they sit pretty wobbly at the moment.

@TheActionBastard 5 жыл бұрын

This is a solid half of my day... I watch youtube videos about physics and electronics. Please keep making these... I'm broke or I'd just do something to help rather than ask. ;)

@sidkapoor9085 8 жыл бұрын

Can u please do a video on energy? On Wat it really is/ what it is physically??

@jacobcluff6382 8 жыл бұрын

+Sid Kapoor mass is bound energy. Mass with no kinetic energy = E/c^2.

@sidkapoor9085 8 жыл бұрын

+Jacob Cluff yeah but it's way more than that. The actual conversion process and how it manifests itself...

@chbrules 8 жыл бұрын

I love Peanut Butter Sandwich Space Time

@sonnick 8 жыл бұрын

This is so beyond my understanding.....but incredibly interesting and equally awesome!

@alexcayer9377 8 жыл бұрын

Favorite channel ever!

@Poop_Deck_Pappy 8 жыл бұрын

And still the best thing on the interwebs.

@MusiCaninesTheMusicalDogs 8 жыл бұрын

Not long ago I saw that type 1a supernovae are not such perfect standard candles as previously thought. Does anyone have any comments about it!?

@TsoiIzAlive 8 жыл бұрын

Pancakes

@11superchelseafc 8 жыл бұрын

+L Galicki yeah I think you're referring to the "weirdos", Type 1a supernovae that are either much more or much less massive than the Chandrasekhar limit.

@pseudorandomly 8 жыл бұрын

+L Galicki There appear to be two scenarios that result in supernovae that are classed as Type Ia -- the scenario described in the video and a "double degenerate" scenario that is the merger of two white dwarfs. There is ongoing research to determine the possible observational differences between the two scenarios and whether the dichotomy significantly impacts the use of Type Ia SNE as standard candles. The Wikipedia article titled _Type Ia supernova_ has more information.

@senorbeast09 8 жыл бұрын

+Brandon Martin ah yes, it must be "weirdos" when science doesn't make sense just call it weird.

@garethdean6382 8 жыл бұрын

+L Galicki The issue is how standard the candles are, nothing is ever perfectly identical, perfectly repeatable. It's been known since their discovery that such supernovae have some variability, the issue was that it was surprisingly low, it could be ignored so long as your desired accuracy was at most as good as the supernovae variability. What recent discoveries show is that such supernovae are slightly more variable than thought, enough to add uncertainty to any measurements made using them but not in this case to affect the outcome. For that you would need something that systematically affected the brightnesses over time, 'faking' an accelerated expansion effect.

@charleskingReal 8 жыл бұрын

Dark Energy is a scalar field, a strange type of field whose density doesn't change with its size. Now, the Higgs field that creates the mass of the quark is also a scalar field, as is the inflaton field that's thought to be repsonsible for Inflation. Are these fields related? Are they the same? Since the answer is almost certainly, 'We don't know,' how would we find out?

@pbsspacetime 8 жыл бұрын

+Charles King Yup, everything you said is right, including the "we don't know" part. Well, the scalar field responsible for inflation is at a vastly higher energy scale than that responsible for dark energy, so that means they aren't trivially identical. But are they related? Could be, since we don't know what causes either. We'll definitely get back to this in a future episide.

@bobsmith-ov3kn 8 жыл бұрын

+Charles King Your mom is a scalar field

@delawarecop 8 жыл бұрын

+Charles King All current cosmological models are inherently flawed because they are based upon the false assumptions made by Einstein wrt General Relativity and the One Way Sped of Light. Einsteins theories are inherently flawed because he wrongly assumed that Quantum Entanglement was IMPOSSIBLE because it would mean 'spooky action from a distance', but Entanglement has subsequently been proven as scientific fact. So if we go back to the fundamentals of Quantum Theory where light propagation results from electron potential drops, by INSTANTANEOUS physical displacement in space-time, then Quantum Entanglement suggests that the resulting photon must also traverse space-time instantaneously by the same displacement - until it is observed/measured at any point in time, just as suggested by the Wheelers delayed choice quantum thought experiment as recently confirmed by Professor Andrew Truscott of ANU. Thus cosmology needs to be re-written to accommodate INSTANTANEOUS light propagation - until the wave collapse is initiated by the interaction of Intelligent Consciousness, none of which has any time constraints.

@charleskingReal 8 жыл бұрын

+PBS Space Time Thanks. That's a good point, the theories should place bounds on the densities of these fields that distinguish them. I brought this up because, while the scalar fields have been around for a long time as mathematical ideas or effective field theories, it's only with the discovery of the Higgs boson that we've had proof that a fundamental physical field is actually scalar. (At least, this is how I interperet it, correct me if I'm wrong.) They're pretty hard to understand intuitively, but we can no longer regard scalar fields as just something put in to make the maths work nicely. [Gotta love youtube comments like the one below, which start off by telling us Einstein was wrong.]

@PyrrhoVonHyperborea 8 жыл бұрын

+Charles King "a strange type of field whose density doesn't change with its size." - there's a word for that sort of thing: nonsense! If an energy-field doesn't change it's density in response to a widening, we are faced with a blatant violation of the principle of conservation of energy, as it's overall energy-content actually increases over time. Thus you contradict one of the most basic premises of physics!

@247gatorfan 8 жыл бұрын

As usual, all of this is way over my head. But I always feel smarter afterwards!

@AstroTorch 8 жыл бұрын

These videos seem to be following my astro course suspiciously closely..

@foobargorch 8 жыл бұрын

+Evan. www.tylervigen.com/spurious-correlations

@PyrrhoVonHyperborea 8 жыл бұрын

+foobargorch xD Thanks for that link :'D

@feynstein1004 8 жыл бұрын

+PyrrhoVonHyperborea It was really interesting.

@luvr381 8 жыл бұрын

If space is made up of a welter of virtual particles, does expansion mean an increase of virtual particles?

@xXboingXx 8 жыл бұрын

Huge high five for producing Space Time, it's by far my favorite KZfaq show. My questions for this episode are: If dark matter attracts and binds mass together (separate of gravity), while dark energy dynamically expands space itself (at an accelerating rate), are there any observable relations between the two in the history of space expansion? My guess is that there is no correlational data to suggest they interact with each other in any way. It's almost as if dark matter affects the main stage of reality from backstage, and dark energy is the fabric of space itself.

@garethdean6382 8 жыл бұрын

+WeeBoingBoing Pretty much, dark matter delayed dark energy's dominance by billions of years but in the end it was little more of a barrier than normal matter.

@musicmakesyoustrong 8 жыл бұрын

Your channel is amazing! :)

@hajorm.a3474 8 жыл бұрын

NOT first. amazing episode

@bigeteum 8 жыл бұрын

sometimes i wonders if there is alternative explanation for the redshift, like if its cause was not due to expansion of the universe but because another strange property of matter or space.

@neeneko 8 жыл бұрын

+Marco aurelio Guerra this is possible, but in order for it to be the case, all sorts of other things would also have to be wrong. Redshift is derived, if it was not ocuring, all the physical laws that lead up to it would have to be revised too.

@vladimirseven777 8 жыл бұрын

Redshift taken from sound physic and applied to light (and it suppose to be not exactly the same). By applying it back someone can say that our Earth grows with every thunderclap. Also to be affected by growing space photon should have length (what is photon exactly?). To be absolutely sure that we see proper effect we also should be sure that it is the same photon emitted by let say Helium atom (not re-emitted by anything) - we must be sure that during all several billions light years between us and emitter photon was affected only by growing space (absolutely empty plain space for several billion light years). And we see those red far away galaxy in several billion years not because we can't see blue one nearby due to properties of red and blue light - we saw red Sun every evening and morning and that doesn't mean Universe grows every morning and evening. I'm OK with any theory but I would like to be sure that every possible explanation counts, not some first one "It can be explained by theory of Space Worms" - "OK, that's enough".

@PaxTorumin 8 жыл бұрын

+Vladimir Olegovich You raise some excellent points. It could be magic. Or maybe god did it? Or perhaps it is all an Illuminati conspiracy to control our minds? Expanding space is just one theory with the most evidence that makes the most sense, but a good scientist like you must give equal thought to all possibilities, no matter how much or how little evidence there are for any of them.

@AlexPaincakes 8 жыл бұрын

I really love this channel.

@isaiasovelar4434 7 жыл бұрын

I really have no clue what this guy is talking about, but it is so entertaining listen to him talk

@CasinomanCT 8 жыл бұрын

Man, I wish I was smarter

@garethdean6382 8 жыл бұрын

+CMCT - Slot Machine Wins! Learn something, doesn't matter what or how little every day. You'll get there eventually.

@J0kecaster 8 жыл бұрын

+CMCT - Slot Machine Wins! I love these videos, because sometimes I can trick myself into thinking I'm pretty smart. Politics, law, philosophy, medicine, art, music none of these subjects make me feel as intellectually intimidated as SPACE TIME! It's a great feeling.

@SineOccasu 8 жыл бұрын

I look forward to Wednesdays on KZfaq

@KarnKaul 8 жыл бұрын

I like how the videos contain typos that are later corrected via annotations: it shows that they treat their subscribers more like beta testers than end customers: content, delivery, and timeliness are more important than meta-factual nitpicking.

@mrityunjaysah178 6 жыл бұрын

I really love this channel thank you

@kwinvdv 8 жыл бұрын

How does the relation of the apparent brightness and distance to us of these standard candles (white dwarf supernova) account for unknown amounts of dust/gas between us an it?

@Stevo1361 8 жыл бұрын

The brightness of the supernova is only a baseline of which to measure the red/blue shift accurately. So because the standard candle brightness is always the same, they can relate the faintness of the supernova brightness to distance and the amount of red/blue shift of the photons to an accurate rate of expansion between us and the supernova. Photons redshifting means it's moving away from us at an accelerated rate. Because these standard candle photons are redshifting it means there is a "force"/energy which is "fueling" that expansion. Scientists are able to calculate that the force isn't anything we can currently see or measure directly because the known "forces" do not equate to the rate of observed expansion. Therefore an unknown "dark" energy needs to be inserted into the equation. Does that help?

@kwinvdv 8 жыл бұрын

No, because I asked about how sure the relation of faintness and distance is, if there would be an unknown amount of dust or gas between us and it, which would also alter the perceived brightness.

@Stevo1361 8 жыл бұрын

Kwin van der Veen, i get what you mean. I would guess that if the photons were affected by any matter whether it be gas or dust that they would not reach the Earth. Remember that photons travelling at C (the speed of light) do so in a straight line. So if a bunch of photons/light were to be ejected from a supernova and there was a gas cloud between it and the earth then some of the photons would be colliding with the gas and others would pass right through and continue onto Earth unaffected.

@pseudorandomly 8 жыл бұрын

+Kwin van der Veen These are, of course, things that astronomers are concerned about. Various observational and analytical techniques have been developed to address this very problem. You might find this interesting: arxiv.org/abs/1601.05659

@michaelsommers2356 8 жыл бұрын

+Kwin van der Veen You are correct that such things must be taken into account. Differences in the light curves of the supernovas must also be taken in to account. It's more complicated than just measuring the peak brightness of the SN.

@sammysalter 8 жыл бұрын

I'm willing to put a cheeky 20p bet that the whole dark matter and dark energy things are the modern day equivalents of the luminiferous aether - a logical outworking of our contemporary understanding that long term will be explained by some fundamental shift in our understanding of physics.

@sammysalter 8 жыл бұрын

That was roughly my point, except it was about the luminiferous aether rather than phlogiston.

@pseudorandomly 8 жыл бұрын

+Sammy Salter You may, of course, be right, but at least for dark matter, there is an accumulating pile of observational evidence that it is quite real. And there are ongoing searches to identify the dark matter particle. Currently, it looks very much like you'd lose the dark-matter half of that bet. You have a much better chance with dark energy, though the fact that it is neatly accounted for by the simple addition of a constant term to the equations of general relativity, and has a ready explanation in terms of vacuum energy (though we don't understand how yet) seems to indicate that a "fundamental shift" isn't going to be necessary. Quantizing gravity may do the trick. (A "fundamental shift" would be exciting, though!)

@PyrrhoVonHyperborea 8 жыл бұрын

+Sammy Salter Michelson-Morley-Experiment! - I found it :) The problematic assumption being, that a certain interpretation of how the dubious "aether" would work was tested, instead of the possibility for any such medium *_at all_* - which basically amounts to strawmanning (for comparison: I am an atheist, but I wouldn't ever go as far as to say, that the rebuttal of a single "proof of god" would justify the conclusion that "therefore" any idea/possibility of god[s] was refuted; that would be a non sequitur! - as logical, thoughtful debaters, we have to do better than falling for such fallacies!). With GR, we are actually given a theory, that describes space as an impressionable, curve-able medium (the fabrics of space-time) - something that may actually remind us of [the] "aether[-theory]" (the earliest attempts to develop a theory as such?... am I even right to assume, that that is your perspective onto that?) of days past, in contrast to the even [much] older idea of complete, absolute emptiness (some sort of divine grid (matrix) for everything to exist within)!

@PyrrhoVonHyperborea 8 жыл бұрын

+Pseudorandomly "[...] though the fact that it is neatly accounted for by the simple addition of a constant term to the equations of general relativity,[...]" - that's not a logical argument. But I addressed that already in a comment of my own underneath this very video (more than an hour ago), and I'd prefer not to repeat it here, for fear of falling victim to some potential auto-spamfilter for matters of repetition (and be ghosted for that reason). Furthermore: if vacuum energy is a sort of energy at all, it would logcally follow, that it must be finite, and thus could not provide for eternal, continuous expansion. If it drives expansion, then it must deplete for that reason; something's gotta give! _"quantizing gravity_ (i) _may do the trick",_ to lead exactly to the _fundamental shift_ Sammy was hinting at... Furthermore, that dark-matter thingy is also dubious; a more thorough understanding of how cosmic expansion works may also grant us the key to solve the dark-matter problem as well, w/o the introduction of that modern obscure phlogiston (like WIMPs) you are hinting at. - - - (i) a better understanding thereof

@pseudorandomly 8 жыл бұрын

PyrrhoVonHyperborea "If it drives expansion, then it must deplete ..." No. Vacuum energy is a property of space. More space due to expansion == more vacuum energy. Quantizing gravity is unlikely to alter general relativity any more than quantizing electromagnetism altered Maxwell's equations. I can't see that as a "fundamental shift", though it might explain why the vacuum energy is so much smaller than naive calculations indicate. "... that dark-matter thingy is also dubious ..." Time will tell; it'll be a lot less dubious if and when the dark-matter particle is discovered. In the meantime, there is mounting evidence from galaxy cluster collisions that dark matter is quite real. It's also quite compelling that the same amount of dark matter solves problems in a number of very different astrophysical situations.

@siliconstate 8 жыл бұрын

I just love this!

@yeshwanthvejendla8385 8 жыл бұрын

Thank you for answering my question

@jesusbarron1351 8 жыл бұрын

yall needa respeck space

@nathangek 8 жыл бұрын

+jesus barron R.. E.. S.. P.. E.. C.. T.. RESPECT.. *buzzer* WRONG!

@CBOLES 8 жыл бұрын

"All tree of yall. I ain't gonna say it no more"

@jayb8491 8 жыл бұрын

Im 14 so most of this goes over my head but is still interesting nonetheless

@jayb8491 8 жыл бұрын

Bob O. thank you Bob i will start doing that :)

@Michb3ck 8 жыл бұрын

+harjay bajwa I am 29 and I still do that. Very good advice.

@frankschneider6156 8 жыл бұрын

+Bob O. Have you seen Lincoln in person ?

@frankschneider6156 8 жыл бұрын

Bob O. But you served in the civil war, didn't you ?

@jayb8491 8 жыл бұрын

Bob O. you have the experience so ill take it

@Forced2 7 жыл бұрын

These videos are great man, I think alot more people should take some time of their life everyday to watch some and get educated on our universe.

@tweiss229 8 жыл бұрын

Where do you get you music for the episodes? I love this channel! Thank you so much!

@mortadhaalaa5907 8 жыл бұрын

A possibly irrelevant question: When photons travel through the expanding universe and get red-shifted, where does the lost energy go?

@HoD999x 8 жыл бұрын

+Mortadha Alaa i would assume that a short blue ray of light turns into a long red one, but physicsgirl disagrees

@kapoioBCS 8 жыл бұрын

+Mortadha Alaa To the expansion of spacetime

@ShapeDoppelganger 8 жыл бұрын

+Mortadha Alaa Talking about physics girl channel, she hinted on her channel that this would be one of the few ( or only, can't recall now) ways of losing energy on the Universe. So when a photon is red-shifted it's energy is gone. Now how this works I have no clue yet. But it's plausible.

@omegasrevenge 8 жыл бұрын

No energy is lost. The entire packet of energy is simply distributed over a larger space.

@MrPipsLab 8 жыл бұрын

+Mortadha Alaa I believe the answer to this is: It goes into potential energy. The photon's total energy includes its gravitational potential energy. So as it moves away from a massive object the energy gets moved from the photon's energy into potential energy, red shifting the light. The opposite happens when EM waves travel towards massive objects and they blue shift.

@OnGamerLINE 8 жыл бұрын

If the rate of expansion is growing, at a given moment in time does the expansion rate could be faster than the speed of light, redshift would be infinite and light couldn't reach anything?

@LorenzoCianiS 8 жыл бұрын

correct

@DeFraans 8 жыл бұрын

+‫הלל שרביט‬‎ I'll give you this: the expansion is independent of your position in space. Things that are further away, move away faster from you, like little chuncks in a growing bread in an oven. In the Universe, there is a point where that expansion already reaches the speed of light. That's the edge of the visible Universe, therefore there is a difference between visible and physical Universe,

@frankschneider6156 8 жыл бұрын

+‫הלל שרביט‬‎ Actually there are galaxies already receding from us faster than the speed of light. So the space between us and them grows by more than a light year per year. If we just wait some time, we won't see any galaxies anymore, except for those of our local group where gravity overcomes the expansion.

@BosonCollider 8 жыл бұрын

+‫הלל שרביט‬‎ The rate of expansion has units of 1/time and cannot be larger than a speed. However, expansion rate times some reference distance has units of speed and can be bigger than the speed of light. But this depends on the reference distance you pick, not on the expansion rate (apart from whether it is positive or negative). If the expansion rate is positive and the universe infinite, you can always find two points such that the proper distance (as defined in earlier PBS videos) increases with time faster than the speed of light, no matter how small the expansion rate is. However, this is more subtle than "if the proper distance to a point increases faster than the speed of light I can't reach it". If the expansion rate were constant with time rather than exponential you would still be able to reach any point from any point. Whether or not you can do that depends whether the integral of dt/a(t) converges or diverges, where a(t) is the scale factor at any time.

@omegasrevenge 8 жыл бұрын

We call the observable universe "observable" and not the "entire" universe because it is already expanding faster than the speed of light at the edges of the observable universe.

@MatthewStauffer 8 жыл бұрын

Oh my god, the last line had me ROLLING for no apparent reason.

@Anjrelito 8 жыл бұрын

Can't wait for the new video every time lol!

@texaninvasian 8 жыл бұрын

How is light waves shifting into longer wave lengths not an evolution of the particle? Since light is mass less and therefore timeless I thought it could not experience evolution in the way massive particles can? What separates this process from something like electrons changing chirality?

@patrickramos1748 8 жыл бұрын

light is soooo strange ;-;

@ShapeDoppelganger 8 жыл бұрын

+texaninvasian It does not experience evolution, but it's loss of energy is caused by the expanding space itself. I think that soon the physics girl channel will take on this topic, as she hinted it on her last episode.

@ShapeDoppelganger 8 жыл бұрын

+texaninvasian Just to add, we can measure both Red and Blue shifts, and have many different sources that makes us certain that it is not a evolution of a photon, but of space-time.

@omegasrevenge 8 жыл бұрын

They don't undergo this process by themselves, but the space they occupy stretches, and the stretching of a photon with a static amount of energy over a bigger amount of space is the redshift.

@ShapeDoppelganger 8 жыл бұрын

abschussrampe I thought the same, but then the photon is not a point like going up and down? I mean, how big is a photon to experience an event like that, it's so strange. This is those times when that wave-particle duality makes us crazy.