PBS Space Time - 2022-02-23
Take the Space Time Fan Survey Here: https://forms.gle/wS4bj9o3rvyhfKzUA PBS Member Stations rely on viewers like you. To support your local station, go to:http://to.pbs.org/DonateSPACE ***** Sign Up on Patreon to get access to the Space Time Discord! https://www.patreon.com/pbsspacetime Reality has cracks in it. Universe-spanning filaments of ancient Big Bang energy, formed from topological defects in the quantum fields, aka cosmic strings. They have subatomic thickness but prodigious mass and they lash through space at a close to the speed of light. They could be the most bizarre undiscovered entities that actually exist. Check out the Space Time Merch Store https://www.pbsspacetime.com/shop Sign up for the mailing list to get episode notifications and hear special announcements! https://mailchi.mp/1a6eb8f2717d/spacetime Hosted by Matt O'Dowd Written by Jason Segall & Matt O'Dowd Post Production by Leonardo Scholzer, Yago Ballarini, Pedro Osinski, Adriano Leal & Stephanie Faria GFX Visualizations: Ajay Manuel Directed by Andrew Kornhaber Assistant Producer: Setare Gholipour Executive Producers: Eric Brown & Andrew Kornhaber Executives in Charge (PBS): Adam Dylewski, Maribel Lopez Director of Programming (PBS): Gabrielle Ewing Spacetime is produced by Kornhaber Brown for PBS Digital Studios. This program is produced by Kornhaber Brown, which is solely responsible for its content. © 2021 PBS. All rights reserved. End Credits Music by J.R.S. Schattenberg: https://www.youtube.com/user/MultiDroideka Special Thanks to Our Patreon Supporters Big Bang Mark Evans David Taiclet Ben Dimock Daniel Alexiuc Nenado763 Peter Barrett Nils Anderson David Neumann Charlie Leo Koguan Sandy Wu Matthew Miller Ahmad Jodeh Alexander Tamas Morgan Hough Juan Benet Vinnie Falco Fabrice Eap Mark Rosenthal David Nicklas Henry Van Styn Quasar Supporters Alex Kinsey Alex Kern Ethan Cohen Stephen Wilcox Christina Oegren Mark Heising Hank S Hypernova Supporters william bryan Sergio Bonfiglio drollere Joe Moreira Marc Armstrong Scott Gorlick Paul Stehr-Green Adam Walters Russell Pope Ben Delo Scott Gray Антон Кочков John R. Slavik Mathew Donal Botkin John Pollock Edmund Fokschaner Joseph Salomone chuck zegar Jordan Young m0nk Daniel Muzquiz Gamma Ray Burst Tony Affinito Lillith Montgomery Avi Yashchin MHL SHS Kory Kirk Joshua Friede Terje Vold Anatoliy Nagornyy Sam Kirkpatrick comboy Brett Baker Jeremy Soller Jonathan Conerly Andre Stechert Ross Bohner Paul Wood Kent Durham jim bartosh Nubble Chris Navrides Scott R Calkins The Mad Mechanic Ellis Hall John H. Austin, Jr. Diana S Ben Campbell Lawrence Tholl, DVM Faraz Khan Almog Cohen Alex Edwards Ádám Kettinger MD3 Endre Pech Daniel Jennings Cameron Sampson Pratik Mukherjee Geoffrey Clarion Nate Darren Duncan Russ Creech Jeremy Reed Eric Webster David Johnston J. King Michael Barton James Ramsey Justin Jermyn Mr T Andrew Mann Isaac Suttell Devon Rosenthal Oliver Flanagan Bleys Goodson Robert Walter Bruce B Simon Oliphant Mirik Gogri Mark Delagasse Mark Daniel Cohen Brandon Lattin Nickolas Andrew Freeman Shane Calimlim Tybie Fitzhugh Robert Ilardi Eric Kiebler Craig Stonaha Martin Skans The Art of Sin Graydon Goss Frederic Simon Tonyface John Robinson A G David Neal Kevin Lee justahat John Funai Cass Costello Tristan Bradley Jenkins Kyle Hofer Daniel Stříbrný Luaan AlecZero Vlad Shipulin Cody Malte Ubl King Zeckendorff Nick Virtue Scott Gossett Dan Warren Patrick Sutton Daniel Lyons DFaulk Kevin Warne
As an old retired welding metallurgist it finally occurred to me on watching this episode that the topological defects you describe are very much like the grain boundaries that form when a weld or a freshly-poured steel ingot cool and solidify. So, more and more it seems that the early formation of the universe was more like a solidification/precipitation event, rather than a "big bang" from a single point. There are many other analogs between the universe formation mechanics you describe and solidification mechanics of metals - grain boundary energy, crystallographic phase orientation angles, and such. If I was younger I might almost feel compelled to investigate quantum mechanical relationships in metallurgical solidification phenomena - as it is, I am just happy to continue growing with your show.
it can still be perceived as a "big bang". imagine a drop of molten metal falling upon a hard surface from the perspective of the hard surface - the metal / heat spreads out in all directions, seemingly appearing at a single point, cooling at a rate consistent with the amount of material in any given area. areas where the metal is thinnest/shallowest cool fastest, others retain heat for longer. and as you say, grain boundaries everywhere.
Big brain analogy.
Grain boundaries are indeed one type of topological defect. Steve Mould has a video about this on his channel
@C Stockman It’s not a defect. A string is not a defect. It’s a normal part of the universe.
Things tend to repeat themselves or mirror themselves in nature, we can understand the big picture by looking in the microscope.
I can't explain how much I love this show. It's beyond my ability to convey.
Thanks PBS and Matt - you all continue to elevate us all above the minimums of our past.
Hey fam, I hope that you and your loved ones are well. I would like to ask you the most important question ever asked:
Who is Jesus? Not who is He to you. Rather, who is He really?
Jesus is the Son of God, who came to the world as a man. He lived a perfect and sinless life . Even though He was perfect and sinless, on the cross of Calvary God wrathfully punished Him for the sins of the world. 3 days later He rose from death. Now He is seated at the right hand of God, ruling as King over Heaven and Earth.
On the judgment day He will judge you, me and every human being that has ever lived. Those who believed in Him will enter eternal joy with Him, but those who did not believe in Jesus will be sent to eternal condemnation.
So turn from your sins and believe in the Jesus, that you can be forgiven for all your sins, because of His death and resurrection.
Acts 15:11
”On the contrary, we believe it is through the grace of the Lord Jesus that we are saved, just as they are."
Ephesians 1:7
”In Him, we have redemption through His blood, the forgiveness of our trespasses, according to the riches of His grace"
Ephesians 2:8
”For it is by grace you have been saved through faith, and this not from yourselves; it is the gift of God,”
John 11:25-26: "Jesus said to her, 'I am the resurrection and the life. The one who believes in me will live, even though they die; and whoever lives by believing in me will never die. Do you believe this?'
1 Corinthians 6:14: "And God raised the Lord and will also raise us up by his power."
Romans 6:9: "We know that Christ, being raised from the dead, will never die again; death no longer has dominion over him."
The way Matt explains stuff always makes me feel like I'm in the future listening to someone talk about all this.
Science-Watch-Suggesss - want some?
Why in the future?
@Ashley Because it seems like the kind of knowledge on display is beyond the level that we know to exist in society, but in fact these understandings already do exist
This is shockingly comprehensible and well-explained, even for us non-physicists.
Dan Nguyen You say that like you can ever completely know something, or like it's possible to be certain you completely understand anything. Knowledge is relative and fluid. Knowing the limitations of your understanding is a mark of intelligence. Every topic can be taught at varying and ascending levels of complexity. I am sure there are biological concepts I understand at a deeper level than the elementary understanding attained by scientists outside of the field, in just the same way that my surface-level understanding of physics is sufficient for me and my purposes. For me to go around saying that people only "think they understand" DNA transcription because they don't have an expert-level mastery of the topic would be as pointless and unhelpful as it is condescending and arrogant.
These videos are aimed at “non-physicists”
Holy Dunning-Kruger Batman!
@Donald Parker Did you read the comment thread? I'm not claiming to have anything beyond an entry-level understanding. I do not understand why y'all are being so elitist about this stuff. Science isn't about gatekeeping.
Dan Nguyen Why do you even watch these videos if your goal is not to try to understand them? I mean did you just show up to belittle strangers on the internet?
I don't speak English natively and I never converse with it with my family and friends, plus I fail math, physics, chemistry so badly at school—but I understand 60-100% of things explained in this channel, and I generally understand math better with English. This language is so efficient for such purposes and thus I can prove to myself that school doesn't define my intelligence at all.
School is only supposed to teach you how to learn, how to think (not what to think), basic language speaking/writing skills, basic mathematical skills, basic societal group/obedience to social norms skills (yeah, they are skills). Like many skills, some folks are more talented than others in specific area, and thus, develop them more quickly and completely with proper education.
Children, like every other intelligent creature n the his planet, want to learn. School is supposed to give them the tools, skillsets, discipline (let a kid discover and then learn about what they are interested in, and they focus like lasers) and the encouragement to strive to better themselves, and their hey will. Children inherently want to be adults.
Funny how society don't want them to be, yeah? Almost like the corporatists know you cannot sell an adult anything they don't already want or need, but you can sell a child anything you want whether they need it or not.
Knowledge is power. Ignorance is slavery.
Finally, a video that doesn't just explain what a topological defect is, but also explains which specific phases of what were transitioned between.
Agree, that's why I live pbs space time. They not only give broad explanation for a layman but also give some theoretical background. Episode about magnetic monopoles was also brilliant. The only thing I'm waiting for is how does the freakin' Z boson work. Anytime someone talks about weak force it is always through W boson. The only one explanation I found was when Susskind was giving lecture about Higgs mechanism but he called it 'ziggs'.
Back to the topic, shouldn't cosmic strings also have some form of event horizon and as a consequence emit hawking radiation?
@Oskar Skalski An episode on neutrino detection would be cool. As far as I know, neutrinos only interact via the Z boson.
I already have proof and also the machine tesla spoke of ..not the death ray that's silly ...but the oscillator machine the real one originally intended ... not the public available design ....don't belive me check out a few of my viedos ....
mind you its made literally bits of everything .....but is really easy to make one and works great once scaled ⚖to the right size.... but even with the one I have you could easily achieve free energy.... I don't have an efficient enough generator, for the size as there is not quite enough torque... and when you see the video you'll know why also it has to be primed and externaly started but once up to speed all is 100%+
This is one of my favorite videos from you all so far, definitely top 10! The fact that you wrap up seemingly separate concepts (vacuum decay, cosmic strings, and gravitational waves), and do so really elegantly, is that perfect blend of entertaining and educating.
That was one of the best Space Time episodes I've seen. Keep up the stellar work!
Pun intended?
@Golden Warrior No, just an astronomical coincidence.
This is one of the best, if not the best, descriptions I've run across about how cosmic strings came into being, what they do, and what we would need to see as evidence for them. Thanks for what you do, Matt, et al!
What lucid descriptions and depictions Matt and the Spacetime graphic artists provide! I get it! Thanks for making so much tractable to this lay audience of one!
The visual of the cylindrical vortex finally made the strings concept click in my head. Calling back to the monopole made that one click as well. Thanks for doing such a great job!
The videos this channel puts out has kept me sane for the past two years. Can't thank you guys enough
In order to make a nice clear argument in support of string theory, scientists must make at least one video daily, extolling the virtues of a theory which can never be tested. If they were to miss a day for any reason, people might start thinking for themselves.
@mrquicky so what are you saying exactly? I'm not thinking for myself because I watched a video that featured a mention of string theory in it?
@mrquicky Can't be tested yet.
@fgutz1970 maybe we should stick with experiments that CAN be performed.
@mrquicky Huh. Well, Einstein had theories of gravitational fields and curved space time that weren't proven until after he was dead. Sometimes the theories come first and the ability to test them comes later. Restricting ourselves as you suggest limits the boundaries of creativity and imagination. The practical and everyday application of some of Einstein's theories are now used for things as basic as GPS satellites.
If I could have explained these tough concepts as well as Matt I would have stayed a teacher. The SpaceTime team is remarkable, thanks for all the hard work
I'm curious how these knots in the higgs field might interact with black holes? Would the black hole destroy the string, or would the cracked higgs field affect the black hole in some way?
We would probably need a theory of quantum gravity to know that. Not sure if Classical GR+QFT in curved spacetime cuts it.
@Codetoil if gravity could be considered a force I imagine all other forces are affected and stopped from transmitting information out of a blackhole meaning it at least gets snapped in half
i must wonder if some advanced civilization could manipulate massive objects as they fell into a blackhole in order to transmit information out of it using gravitational waves
@1000 subs with no content snapped in half or bent around it?
I guess, going way back to the Space Time video on blackhole Hawking radiation, we can sort of assume that 1) the string would get pulled in and treat the blackhole's space time like regular space time (so, it wouldn't break, but maybe swirl around "the" singularity/discontinuity in the black hole). 2) There would be a kind vibration on the cosmic string propagating from the event horizon, much like Hawking radiating, due to the Fourier transform of the string's "state" being different than if the black hole wasn't there. I don't know where the energy would come from to make it happen though.
This is the very first time I've completely understood the subject. I love this channel so much.
Amazing, you've taken such a complex and abstract mathematical concept, and made it easy to visualize! Well done again :)
If there is no other intellegent life out there, its crazy to think that Matt is literally on of the smartest people in the Universe
Is the Higgs phase angle something that could theoretically be measured? Or are cosmic strings the only indication of a change in phase angle?
I kind of got from this that they’re looking for that in the junctures, that they’ll see what they’re expecting there to look for elsewhere, but I was thinking the same question and might have just heard the answer I was looking for.
An angle between what and what? What sets the "zero degrees" mark that it would be measured from?
@Stephen Ball A circle needs not start at any point for us to say that a certain point is 0. we can then assign + or - °s as we see fit.
If we can...
@Stephen Ball I'm not sure what you mean. Are you saying you need a fixed point? Can't you simply set a fixed point? For example; suppose you have two points in space. Is there an experiment that could determine if the higgs phase angles at these two points are the same direction? Or are you saying that choosing a reference point for phase angle doesn't make sense in this scenario?
@Brandon Munshaw the phase angle describes the angle away from 0°. You can arbitrarily assign where 0° is, because the universe doesn't assign one for you. So, there isn't a universal measure of phase angle. (If you had access to other higgs field regions in the universe, maybe you could determine their phase angle *difference*. But any assignment of value would be a human choice.)
What happens when a cosmic string lashes through an solid object like the earth, or an neutron star? Or a black hole?? 🤔
Anyone else just love this guys voice when he explains stuff? I know he could narrate like any show on space or nature.
Beautifully explained. Thank you so much for your insights, Dr. O'Dowd. <Hats off with a bow>
This is always so educational and well-structured. Although I very much likened the idea of this kind of thing, I was somewhere lost in the end, because it got a little abstract for me. But I think, thats just my limited imagination. :D
I like that I’m finally starting to understand all this because of you and this channel do such a great job of explaining the pieces and the importance of each part of all theories. 🙏🏼 🇨🇦 ✌🏼
Don't get too excited. A giant chunk of theoretical physics is, you guessed it; completely theoretical.
Basically, these people are making 2nd and 3rd order assumptions from real data regarding things there is no evidence for or real understanding of.
There isn't much difference between this guy's rant and a religious sermon. There a physicists who would tell you that 50% of what he just said is fiction.
We don't know nearly as much as certain physicists want you to believe they know.
Given how these cosmic strings behave and should affect space and gravity while also being not directly observable due to not existing in 3D space, I wonder if they'd be a candidate for explaining Dark Matter.
They aren't. We have yet to actually discover or detect dark matter (and it is still theoretical, if a very strong theory), but we do know a lot about the properties it has.
For example, it must be diffuse, and it can't interact with itself in any way other than gravitationally. Cosmic strings are basically the opposite of diffuse, and as discussed, they interact with themselves rather dramatically, chopping themselves into smaller bits.
The next logical question my mind jumped to was "What about those smaller loops, then?" But those would still be far too scarce and far too massive to act as dark matter (remember, only dozens in the entire observable universe, so even if each one split into a million smaller loops, they'd be ridiculously rare). Plus since they decay faster the smaller they are, if they did split up enough to be a plausible candidate for dark matter, they'd evaporate extremely quickly, which Dark Matter doesn't seem to be doing.
What I wonder is if they could be the foundational building block of some supermassive black holes, jump-starting their growth and development...
@Barefoot could they explain the great attractor instead?
@Barefoot Thank you! I was wondering this same thing, and you answered it perfectly.
Would the existence of these strings have had an observable affect on the structure of the matter on the largest scales? The diagram in the video reminded me of renders of the universe at the largest scale with tendrils of matter creating a connected web. I would think that because of their mass the cosmic strings would attract matter in the early universe and create a predictable pattern.
@Jameilious The great attractor is likely already explained as the Vela Supercluster - you can check out SEA's great video on it here: https://www.youtube.com/watch?v=0w4OTD4L0GQ
What do you mean they don't exist in 3D space? They do.
I’ve been reading or hearing about cosmic strings for close to 20 years but this was the clearest explanation I’ve ever seen. I finally feel like I have some understanding of what they are.
This channel routinely blows my mind in the best way possible. Thank you for the insight, both at a layman's level and a bit more technical. The latter I can't always follow fully, but you're very good at describing things so I at least can get the gist usually.
It is incredible how you can make this concepts so clear and simple to imagine and understands.
Thank you for explaining the difference between cosmic strings and cosmic super strings!
Really well explained video for such a complex topic! I wonder if the fundamental particles we're familiar with can be thought of as topological defects.
I've been intrigued by topology for quite a while now. It seems like one of those math fields that has little to no real-world application... but when applications are found, it somehow is not surprising -- it's too beautiful and compelling not to be 'real' in some sense or other.
Topology is super useful in physics and is the basically the backbone for analysis
@Tony I'd definitely be interested in seeing more videos about topology in physics. Everything I've seen and read about it has been in pure math.
@Poindexter Queue Topology enters the picture basically whenever you are doing anything that involves a notion of "closeness", i.e. can you descibe when things are close and can they separated in a way. Sounds super weird probably, but that is what point set topology is about. Then we have specific well understood examples of topology that give rise to incredibly rich theories. Originally, topological methods were developed to understand objects from geometry, but because analysis itself is way too "specfic" it seems like it is impossible to draw key distinctions.
It started with integration! Physicists and mathematicians alike tried to solve certain differential equations, but it turns out that there was something deeper about the underlying space on which you are sudying your fields. A fantastic example of this are Maxwell equations! Grassmann, Poincare, Cartan, de Rham and co. started developing a theory to understand this. Poincare started in analysis, but seemed to have gotten frustrated and attacked the problem from a different angle, i.e. he started thinking about loops in spaces and triangulations. He then invented homology, which is one of the big developed branches in algebraic topology. On the other hand, Cartan and de Rham pursued the analytic side of things and de Rham managed to prove that differentail froms, that Grassmann and Cartan developed, give rise to the same structure that Poincare's homology theory does!
In a vague sense, topology tries to abstract away very exact details about spaces and tries to focus on very important key disctincitons between them. This does NOT mean that we do not care about analysis anymore, but often some questions are so incredibly difficult and often you care about a certian "yes or no" question, so you want to do qualitative analysis, instead of quantitative. In fact, these days, topology is everywhere in math, to the point where one of the most essentail classes an undergraduate has to take is a beginner course in general topology. Studying graph theory? You can do topology on it. Studying how to provide good signal coverage for say LTE? Sheaf cohomology, a theory in algebraic topology, will save your day. Cancer research? Knot theory seems to be getting attention there. Doing algebraic geometry? Again, there is topology in there and homological methods appear, although in more abstracted algebraic ways. Smooth machine learning, where you want to teach the model to smoothly predict results? Yeah. A recent nobel prize has been awared for results in something called topological quantum condensed matter. There is also a super young field called topological data analysis. Some people are also working on trying to understand deeper philosophical ideas thorugh topology: e.g. Tai-Danae Bradley is doing some very interesting research in using category theory and topology to understand language, meaning and information.
But, classically, whenever your are doing analysis, there is a TON of topology. Like pretty much all the time, especially complex analysis, which is booming with geometry. Example, physicists love Lie Groups, because they perfectly describe continuous symmetries in their analytical models. Lie group theory involves quite a bit of topology, where in fact there is no upper ceiling, depending on how far you want to go. It was super useful to study lie algebras in the context of QFT, so physicists called them quantum groups(even though they are NOT groups lmao).
Yang-Mills, the theory that unifies electromagnetic and weak force, uses a lot of de Rham's ideas afaik and makes use of differential topology.
Hamiltonian mechanics are a geometrization of mechanics, where suddenly your mechanical systems isn't that "analytic" anymore, but becomes a question of geomtry, very vaguely similar to GR. The key mathematical context here is synthetic geometry, which is in a sense equivalent to contact topology. Lots of topology here as well and hamiltonian mechanics are at the center of modern physics. Also, noncommutative geometry is motivated by quantum mechanics and seems to be applicable there and it makes use of K-theory and foliations, as well as other topological theories.
Dynamical systems use tons of topology as well. E.g. control theory might make heavy use of foliations, which you can think of like a slicing of a space into leaves, which can be well understood. Some PDE's can be desribed in a way, where you are looking for a foliation that satisifes certain conditions.
I hope this convinces you that this is a massive field that has tons and tons of applicaitons.
Sabine Hossenfelder says that a theory that is beautiful is no guarantee of it being true or even useful.
@Chris GouletSabine says alot of stupid things, all theories are 'true' in their own 'universe of discussion' wether they apply to reality is not a guarantee but there is value in beautiful theories
One of the most fascinating videos I've ever watched. Thank you for this!
I only just now heard of superstrings and the immediate thought running through my head is: every time fundamental pieces of matter are combined in unusual ways we see unusual kinds of matter like neutron stars and quark-gluon plasma, so what would happen if there were just a bunch of superstrings that hadn't become everyday particles and stayed strings the whole time?
I appreciate the detail they go into here.
I am a bit confused regarding how a topological defect can "become weaker" and "evaporate". I thought the whole point of topological structures is that they are integer in nature: they either exists In some number or they don't, but nothing in between.
I don't think they can actually evaporate. But a string loop can lose its energy and shrink to Plank size. Another candidate for dark matter.
When a string loses energy it becomes straighter. When a loop loses energy it becomes smaller. Loops can smooth themselves out and vanish, but strings cannot.
Remember that a string is made from the cylindrical knot at the center of a rotating field. A loop would be the core of a torus. You can't straighten the field in one dimension to fix the string, but you can straighten it in two to fix the torus, because the ends of the field connect to themselves and can wrap around to unkink.
Someones grasping at straws. Your not alone in feeling frustrated.
@Stefan Schleps learn where the apostrophe goes, smart **
The energy state becomes more uniform. That is what is being said. The string points to events that kept uniformity from happening. When a string dissolves uniformity has been achieved.
Hey Matt! You should do more of these. Before I started trying to understand Quantum Physics 10-15 years ago, I thought "entanglement" was about stuffing 35 college kids into a VW. I've had a pretty extensive background in engineering and hands-on technology, some of it in nuclear power work. I went to school in the 60's and 70's but nobody (except maybe the chairman of the Physics Dept.) had any clue about this stuff. My main trouble in understanding (and probably a lot of others) is that this stuff has almost nothing in common with our everyday environment which forces us out of our comfort zone and into a whole new world of strange behavior. Relating the quantum level to our everyday level probably isn't accurate but might be enlightening. Love the series!
The real question I have is at what point do our existing forces break down into multiple even simpler sub forces and when will the universe expand enough to distribute that energy thin enough for that to happen naturally?
I wish Pbs would do a video on Julian Barbours Hypothesis. I know he published a book but I heard it is a horrible more philosophical than phisical reading.
How he exactly imagines that "reversing enthropy" and denying both Big Bang begining and heat death?
@Mr Sunshine My go to example is the electromagnetic field - the 2 forces are intrinsically linked so anywhere you have force acting one the other reacts to it. In theory if the other forces separated due to the early expansion of the universe, these ones could eventually do the same, changing the physics as we understand and use them. we are talking on timelines that make Heat death is a much more present and looming threat sure, but its interesting to think about anyway.
@Mr Sunshine But it's exciting to imagine that we could cease to exist anytime by random fluctuation.
Although Nuclear War and Ukrainian Crisis is also sufficient
Just felt everything explain in that video sums too the breakdown being done I side a black hole .
We’re already in it .
Cmb is the event horizon and everything break downs toward lower vacuum energy Into to another blank hole .
If physics teachers had taught quantum theory when I was in high school, my life might have gone in a very different direction. This is absolutely fascinating.
This is not just quantum theory unfortunately. This is easily at grad level. To even begin to understand it at textbook level you need QFT(and 2 semester of it) while in second semester you might be taught higgs field. Then a lot of stat mech is needed to understand phase transitions. After you have background you then begin a self study of 4-5 months on top of this to even begin to comprehend these at a true level.
I was taught quantum theory in undergrad, it was horrible and I hated it. It's not taught like this in schools. It's just chalk boards, and solving equations.
He purposely keeps out the math but keeps the fun concepts, but it's ONLY math when you're learning it "for real."
Hi Matt and PBS Staff! First of all, thank you very much for all you.. each one of your videos is so full of incredible content and information, and Matt you are a great presenter! (:
I was reading around the internet about the research work of Yusef-Zadeh and his team at Northwestern University, they talk about incredibly long strands of cosmic ray electrons moving their magnetic fields at near the speed of light and it made me think about this last video on Cosmic Strings.. could those be the cosmic strings you were talking about here?
Thanks again for being such an amazing source of knowledge
Well, Sir, congratulations for, once again, cooking my brain. One question I have that arises from near the end of the episode is: how does one hope to detect these cosmic strings/super strings? Also, when you mentioned that they are under a bit of tension, I had a bit of a laugh. Yeah, I can imagine that being stretched to the size of the universe would apply a little tension 😂 Thanks for these awesome videos!!
One of the more simple ways is to look for gravitational lensing events. The strings are massive enough that they should do something if one is relatively nearby.
Dr. Ed Copeland is probably thrilled this episode has been made. Man loves his cosmic strings!
Could these strings be the foundation on which the cosmic web is built upon? Seems to me something with this much mass in it would have a huge impact on the large scale universe.
Could cosmic strings explain the filaments and voids of the large scale structure of the universe, i.e., the ‘cosmic web’? Even if the strings have decayed, the gravitational effect of their high energy would have created over densities of regular matter (& dark matter) and thus self-reinforcing? Would it leave imprints on the CMB? Also, for that matter (pun intended), could cosmic strings be a dark matter candidate?
More like dark matter... definitely 😁
Not unless those loops split exponentially and we have tiny loops that still weight metric boat loads flying all over the place. But then I suspect we'd being seeing actual impacts, somewhere, someway.
@Yathish s Still need to find Dark Energy then. Seems there are far less candidates for it than Dark Matter, but solving one would make solving the other easier.
@Saran no, cosmic strings as seeds of large scale structures have been largely ruled out sometime ago, due to their CMB imprints
Yes they should have an impact on the CMB but current observations place constraints on their masses because we haven’t seen them yet. And while they would have some effect on LSS formation, it would only be secondary. Original density perturbations from inflation is what seeded the cosmic web.
This one was surprisingly well explained, I'm happy that I understood such complicated subject.
Allow me to conjecture: if a cosmic string is created by the collision of different vacuum decays of the Higgs field, and it is similar in some ways to cosmic superstrings, then we might be able to reproduce quantum strings in a simulation by colliding the vacuum decay of different forces. (TOTALLY IMPRACTICABLE, I KNOW LOL)
Even before they showed the 3D cube graphic, I wondered if this mass could explain how galaxy clusters and filaments formed, and boy does that look EXTREMELY similar…
But the real question is: Are cosmic strings a viable candidate for dark matter?
(I'm guessing not: these things being as dense as they are at a mars mass every 100 meters gives them a lot of the same problems as primordial black holes. If there were enough cosmic strings to make up dark matter, we'd notice the gravitational lensing.)
We do see gravitational lensing from dark matter. If you mean localized lensing, the theoretical primordial black holes would be too far apart and rare for that to be likely to get noticed. The constraints on primordial black holes leave us with asteroid masses as the only feasible mass range for them, and that's not massive enough to create noticeable local lensing.
My first thought with this was that it could explain the way that at the very largest scales, superclusters and what not, the universe arranged itself in a very similar way to that network of strings in a cube that they showed in the video. Maybe they just haven't been thinking big enough in their considerations.
That was my thought too. I'm surprised he didn't discuss the possibility that these cosmic strings could be what dark matter is. He did discuss the obvious confusion people might have between these strings and String Theory strings. But for things that may not exist at all, they seem to know an awful lot about what cosmic strings WOULD be like.
@Dan Schwartz There's also a vast gulf we don't know about them, though. Critical to the question of them being part of dark matter is whether or not they have an irreducible core size. If so, they are a great candidate for at least part of dark matter. If not, they aren't such a great candidate. (To be clear - the "how" of cosmic strings having no irreducible core size is over my head, as is why that matters. I'm going off what scientists weighing in on them as an option have written.)
EDIT: To be clear, though, as a topological defect, they don't so much "contain energy" as a massive object might, so I do see how they aren't bound by a conservation law. I just can't fathom the mechanism.
@Merennulli Last time I checked, there was an on-going debate if dark matter really exist or if maybe just our gravitational formulas may be incorrect and just not work on a big scale. Lensing from dark matter would be a proof that it exists and I've never heard of any such proof up to now.
Hello Matt,
Several questions to peak into a mystery at question 3... Thanks in advance!
1) The Higgsfield#-energy peaks in the vortex centers, who's points aligning as 'cracks' (cosmic strings) through space with high localized Mars-like mass. Wouldn't that result in very 'small', that is low NA, lenses? Hence possibly very tiny (in arcsecs) images, escially for relative large (in arcsecs) galaxies behind them, almost impossible (?) to see? How do these compare?
2) Could the radiated Higgs-energy for sibling-cosmic-string via gravitational (maybe) waving-at-us ;-), also loose energy (just like proposed in cosmic inflation) via particle creation? What would be the theoretical rate of this particle creation? Could this lead to the ever expanding space, hence 'growing Higgs-cracks', to keep producing fundamental particles like electrons and quarks?
3) And if that is likely, could this mean that our 'touchable' universe not only keeps expanding from the inside out (i.e. every 'poins' of space 'grows'), but also (re)populates Itself with new particles along these cosmic stretching cracks? Would this save 'us' from the big freeze?
Thanks again, and hopefully you find these questions as intriguing as probably many of us do. ^^ Love to see you a an ep. on that! :~D
...haha, or hire a PhD to dive in! (~;
Warm regards.
nick
Wow! Didn't expect something as cool and exotic, yet as simple as this to be discovered.
I wonder what makes cosmic strings move and bend against their inner tension, so they can intersect? Since they have a lot of inner tension, why don't the loops just contract and collapse to a point? Do the domain boundary walls have any measureable physical properties?
If strings are discontinuities in the phase of the Higgs field that cannot smooth themselves out, how do they then vanish by radiating energy? I thought they only formed in the first place because they could not simply go away.
They can smooth themselves out via gravitational waves. It just takes a long time. In other words, we don't think there is a faster mechanism for them to evaporate. They formed and remain intact because not enough time has passed to erode them. Although, I'm not sure if non-loop cosmic strings will actually evaporate away, unless the nucleation bubbles somehow end up aligning themselves; does the mean-value theorem apply to this?
if you have a topological loop (like a vortex) you can gradually shrink it to zero radius and it would actually disappear. I guess they might shrink due to radiating their energy as gravitational waves.
only loops can disappear this way because they can shrink. a continuous string can only straighten out over time.
@Brandon Munshaw wouldn't the non-loop cosmic string only evaporate if there is a complete alignment of the higgs field tho?
@Alexander Sannikov that was what I was thinking yeah. but I know physics will behave in stranger ways then simple vector fields, so I'm not quite sure
Pretty sure the cosmic strings can bleed energy by producing loops. Given their literally cosmic length, it probably takes far longer than the universe has existed to dissipate to nothing.
FINALLY THIS IS THE THING I WAS LOOKING UP. One time I went down a Wikipedia hole and found this exact concept but when I went to search for it next time, no dice... I could've sworn I was searching for "cosmic strings," but even ignoring the stuff about string theory, I think all I got was micro-scale stuff... and I was like NO IT WAS LIKE A GIANT CRACK IN REALITY LIGHT-YEARS LONG AND I WANTED TO KEEP READING ABOUT IT but I never found it until now! Thank you PBS Space Time!!!
Maybe I was searching "cosmic threads"... whatevs.
Coal Key - 2022-02-24
Someday I imagine myself in an interview and I'll say, "Well, I'm not a credentialed physicist, but I've watched a lot of PBS Space Time," and then I'll be hired on the spot.
MrHominid2U - 2022-03-11
Or at least in a Comfort Inn commercial
Marcus Bergman - 2022-04-05
"I'm no expert... But I've seen one on TV."
WebX - 2022-05-15
Only thing that would be missing is the actual math.
Robert Kukla - 2022-05-25
Throw in a holiday inn express and you'll champion right through.
John Griffin - 2022-06-24
I'm not an actor, but I play one on TV🤔😅