How fast would I need to flap my arms for LIGO to detect the gravitational waves? If I went from stillness to flapping them at 99% the speed of light, would LIGO detect it?
I would assume that seismic detectors would be able to do this. Maybe on the other side of planet. Just by friction with air there could be enough energy produced for it to be like dropping a bomb.
You would need the same acceleration as any other RAMA, so 300 million meters per second squared, or about 30 million times the acceleration of Earth’s gravity at sea level
@@Beanskiiii They're clearly making his experience of the world better, and they clearly appreciate the compliment. Meanwhile, your horse is so high it shits mountains.
Never thought I'd hear about aliens yeeting themselves across the universe at a fraction of the speed of light, hooning about causing wibble wobbling in space time. Great video, seriously an awesome explanation of LIGO and what it's used for.
The simulated visuals of black hole mergers always make me do a double take, because the resulting black hole seems so much bigger than it should be. I know why it is: the equation for the Schwarzschild radius of a black hole has the counterintuitive feature of radius scaling *linearly* with mass, in contrast with our everyday experience of fluids with near-constant density and thus *volume* that scales linearly with mass. But seeing that play out in simulated mergers still gives the impression of the sum being much bigger than its parts, rather than the reality that a lot of mass has been lost to gravitational waves.
Because it seems to violate dimensional conservation, as if black holes are 1D. I could understand if black holes scaled like the mass was concentrated in an outer sphere, but instead they act like from the viewer's perspective the mass is concentrated in a circle (edge) instead. Also seems amazing that gravitational waves dissipate as if space is 2D (1-sphere) rather than going out in a 2-sphere, yet normal gravitation itself goes out in a 2-sphere (3 dimensions). 🤔
@@tonywells6990 yeah, that threw me for a loop for a while, but I figured out that EM waves are the same way-amplitude goes as 1/r, energy goes as 1/r^2. It’s just a quirk of the fact that we’re almost entirely transparent to gravitational waves, so we can’t build detectors that work like EM wave detectors. And in terms of energy, black hole mergers are unbelievably “bright”; it’s just that we can only interact with that energy in limited ways.
As is sometimes the case, some of these concepts have been used in Science Fiction. Joe Haldeman’s “Mindbridge” used such a gravity wave generating space drive for his aliens. Larry Niven’s “Shipstar” was a small planet sized spacecraft that harnessed some of its sun’s output for it’s propulsion. The chuckle inducing bit though, is the term “Rama-craft”. Someone was inspired by Arthur C Clarke’s “Rendezvous With Rama”
_small planet sized spacecraft_ lol i know you meant that it's the size of a small planet, but at first I read that as you saying that a planet-sized spaceship is small 😂 (and who knows, maybe that *is* small somewhere in the universe!)
Also I remember reading a novel from the 60s where the final twist was that quasars have their huge redshift because they are actually stars turned into propulsion devices for their entire solar systems, and advanced alien civilisations leaving the Milky Way galaxy with them, fleeing from some cosmic fate.
His specialty is presenting only the information a general audience can understand. If you're really interested, check out the Susskind theoretical minimum series for the next level. And if you're still interested, check out a textbook or an actual class on QM or GR from your local university!
I always loved physics, and finding Space Time is one of the best things that happened to me. I look forward to every new episode, I usually watch it first thing in the morning (living in Europe it's often to late for me to catch it in the evening), and I literally have an episode playing every time I go to sleep. It's not only interesting, it calms me down, even on the most stressful of days, and there are a lot of those. So I just wanted to say thank you, from the bottom of my heart, for putting so much effort and love into the series. You guys are simply awesome and you enrich my life ❤
I asked this exact question to Joseph Giaime at LIGO back in 2019. Here is his response: "It is not thought possible for a civilization with our current or near- to mid-future technical abilities to generate gravitational waves strong enough for us to detect. This is because spacetime is quite stiff, and difficult to significantly excite waves in, by moving things lighter than stars. In fact, it is a standard exercise for Ph.D. students in our field to attempt to design such a presently-impossible 'transmitter.' For similar reasons, I've never seen a plausible design to use GWs for propulsion. "
Here was my question: " There has been a lot of attention on the "Advanced Aerospace Propulsion" topic of recent, and I'd like to approach some experts in the field of Gravitational Waves via email. Two silly questions to sip coffee over on a Monday morning: - Suppose there was a vehicle that operated via producing "Gravitational Waves". Would such a craft be detectable via the Ligo Detectors? - What is the feasibility of smaller "Hobbyist Grade" detectors? '
Perhaps some Aliens use gravitational waves for communication, their ability to pass through basically anything can be very useful provided you have technology to detect tiny waves.
It would be like playing a massively long guitar string and you can play an endless amount of notes on just one string. So I could definitely see it being used for communication.
Maybe they use a combination of gravitational and electromagnetic waves. For instance I could imagine electromagnetic waves getting used for short distance communication and gravitational waves getting used for long distance communication.
You just need to have a way for gravitational waves to express theirselves within a closed system. I use magnetic nano particles in a meta material configuration to time develop my MRI like images realigning the each pixelated domain into holographic images of Dark Information Energy reaching forth beyond our spacetime. Sounds fantastic but fear not 🖖 I have made contact and I don’t know how to tell you this 🤷🏻♂️ They are on their way 🫡 th-cam.com/users/shortsubmkTQ6EyU4?feature=share
13:28 It's an apples to oranges comparison -- intensity is amplitude squared. Strain is the gravitational wave amplitude. So you're talking about the 1/r^2 *intensity* decay law for EM waves and comparing it to the 1/r *amplitude* decay law for gravity waves, and then concluding that gravitational waves decay slower. Good one
Hate to burst your bubble, but he really was not the first in many of his famous visions and bon-mots. Nor do I think he really pretended to be (although for my money I do think he was a stuck-up self-promoter, but that's just one man's opinion); those of us who knew 50s and 60s sci fi and popular mechanics type publications knew well enough that the stuff predated his, but then in the 90s this odd Arthur C. Clarke myth just slowly too over.
@@DrWhom I’d agree that Asimov was a better science writer and most of Clarkes ideas weren’t novel. But 2001 had a huge influence on me as a child and the philosophical and evolutionary ideas introduced to me still form me today, even directing career paths. I only have to hear also sprach Zarathustra still today and I perceive it is akin to a spiritual experience for a believer in a deity.
@@DrWhom i suspect they are referring to the fact that Arthur C Clarke wrote a series of books about a craft called Rama that was large and could achieve large acceleration (not the scales mentioned in this episode, but still).
I can't help but smile when the highly speculative nature of this topic is emphasized. I suspect people get the speculative nature when you are talking about aliens right off the get-go, my friend.
That could be. If we do find one it's going to be positively ancient, untold millions of years old. The civilization that built them would've probably collapsed to dust long ago. But that would mean a free planetcraft or attack moon for us if we could somehow get to it.
@@MiguelSedek anything lasting for millions of years is unlikely, but at the very least what we see is garaunteed to no longer exist, like early humans, we've evolved to a point where our past selves are not recognizable
RAMA ... lol, they are totally trolling everyone. I have the Rama series in my bookshelf, and yes that ship was massive and held entire civilizations as they flew through space as a kind of space ark.
I've learned a lot from this video. Lots of facts but the one that stood out to me was that Ligo can triangulate the location of multiple dancing chickens at any given time.
The AMPLITUDE of electromagnetic and gravitational waves decrease with 1/(distance). The power density decreases with 1/(distance^2) for both. The power of an electromagnetic wave or gravitational wave is proportional to the amplitude squared.
Salutations from Brazil! There are just some months since I found this channel in TH-cam, and it is already my favorite science channel alongside 3B1b, with the advantage of updating more or less regularly. The videos are probably the most precise in TH-cam on advanced physics, and watching them is the nearest experience to reading Feynman’s lectures that anyone may find here.
First, props to whoever came up with RAMAcraft. That's a good acronym/reference. Second, I'm really surprised that gravitational waves drop with an inverse law rather than an inverse square. How does that work? I thought that inverse square laws were a natural consequence of the way things expand into 3-dimensional space as 2-d surface.
The energy of gravitational waves do drop with the inverse squared law (like electromagnetism) but it is the 'strain' or amplitude or intensity of the waves that drops as inverse law, same as the amplitude of any wave. The difference is that we detect electromagnetic waves by absorbing their energy in discrete frequencies which are proportional to their energy, via photons. Fortunately for us the way that we detect gravitational waves is based on their amplitude (which is what stretches and compresses spacetime) and not on absorbing their energy.
If they're anything like us, at least some of their young adults with too much free time have fitted Mega-Grav spoilers on their sportsters to do donuts at 3 AM in a quiet solar system where people need to get up and go to work in the morning!
Considering all the reports of our neighbors crafts not producing any sound and that they don't seem to affect more than their immediate surroundings, - it is also quite likely that the craft wouldn't create gravitational wakes at all, or at least not to the extent their mass and acceleration would imply.
Yes, they use time. Crafts move relatively slow in space, but they just throw themselves into future/past as needed. From our perspective they move with absurd acceleration.
We always assume astronomical levels of technical and industrial capacity for alien civilizations. But you have to ask, "Why would any society build a planet sized space craft?"
Why do we always assume aliens will think like we do? Much less build things like we do, or even know our form of math. perhaps they know completely different ways of thinking that would be mind boggling to us.
It's not like we always assume that. We do. But you cannot design an experiment to detect something that we have never thought of. So we are limited to try ideas we humans can think of.
You are quite right, except about maths. (It is maths with an S, you silly American!) The maths is the one thing I know we will have in common with the aliens, as far as the one with the weaker maths goes, barring differences in notation (which can make a big difference).
LISA coming online and us discovering that there's not just signs of Ramacraft out there but lots of them implying a whole galactic civilization and what do we do then is a neat idea for a sci-fi series. :)
Alderaan: You can detect moon sized objects accelerating towards us? Tell me more. Matt: You need a Jupiter sized ship accelerating at 30% speed of light in a second. Buster Machine 3: Hold on my beer!
1:44 LOL. Gotta love the full frontal nerdity on display with the name here. Personally I'd have gone with a Heart of Gold reference, except that the full name's too long, the abbreviation is awkward, and that particular ship works by hacking QM, not GR.
@@emm6064 I mean, yes, but no. What if they're using something other than electricity for their propulsion? some sort of high energy propellent that we have yet to understand, or some bit of physics that we haven't discovered. This *is* a thought experiment after all.
Yes, if conventional then large amounts of energy will have to be ejected in our general direction to counter the existing momentum . But even if hypothetically FTL, I’d speculate we’d see rather bright streak of Cherenkov Radiation. In all cases where particles can temporarily move at speeds faster than the allowable relative lightspeed of the nearby medium, this emission has occurred. We observe this in isotopic interactions and from neutron stars, where light speed in the areas has been slowed down but the same rules should still apply for something transition from FTL to normal space too.
I'm glad that this is a topic that science is capable of taking reasonably seriously. Regardless of whatever alien life may or may not be out there for us to find, thought experiments like this are valuable and useful because they encourage us to constantly seek out new ideas of things to look for and how to see them. It's like militaries and disaster response agencies considering how they would respond to scenarios like "zombie apocalypse."
Lisa & Ligo song - to tune of A Few of my Favourite things. LIGO did land based, and LISA is in space. Little gold cubes, floating free in a space ship. One day we'll find out if gravitational waves, can be low frequency and also high! LIGO land bound, LISA space bound cubes floating free. Science is great, and science is good Knowledge for you; and me. :)
Well I guess it would depend on how far it was away. Like he said the main thing about other signals is that they fall off with a lot greater strength compared to gravity
That depends if it's accelerating through a nebula or through empty space. If it's accelerating inside a nebula it will compress the stellar gas in front of it immensely causing it to glow and maybe even forming a new star or two.
12:34 It's actually really interesting that the sensitivity to detect gravitational waves decreases linearly with distance instead of with the square of the distance like detecting light. Just on the face of it you would think that gravitational wave detectors would be subject to the same inverse square law, but as touched on briefly in the video telescopes measure the "intensity" of light while gravitational wave detectors are measuring the "amplitude" of the waves, not the intensity. And while intensity dissipates according to the inverse square law, the amplitude of waves does not. Or to put it another way, intensity of these waves is a function of the square of the amplitude, so since intensity dissipates using an inverse square law it follows that amplitude dissipates as a linear function of distance instead. (As an aside this is also, from what I can tell, true for sound waves, for instance. Our eardrums detect the intensity of sound waves, which disperse using an inverse square law. But if you want to emulate a similar effect in digital audio you need to adjust the amplitude of the wave linearly to make it "sound" like it's that same distance away to your ear.) Honestly the relationship between intensity and amplitude and the inverse square law could be an interesting topic for a future video maybe, just a thought.🙂
@@michaelmicek Not specifically no. I'm simply talking about how the energy of a wave is proportional to the square of its amplitude. Since energy dissipates with the square of the distance that means the amplitude dissipates linearly with the distance.
“Gravity is the weakest force” “One pair of merging black holes radiate more power than all the visible light radiated by all the stars in the visible universe”
Has gravity is the weakest force, and for instance magnetic force is a lot stronger. In theory, a huge magnetic field may be able to 'extract' mater from a back hole ? Or closer to us : using magnetic field, we could extract mater/gaz from Venus or Jupiter atmosphere from far enough away (for any purpose such as fulling ship tank for instance). Gaz that could be later used in a ion like engine
@@bernardsegonnes1335 Gravity is the weakest force (smallest coupling constant), but the masses involved are very large... What is holding matter (or whatever is left) inside an event horizon is not a 'force'; it's the fact that spacetime is moving 'inwards' faster than the speed of light.
Yes, gravity is the weakest force. Bugs barely notice it. We routinely win against it by lifting anything or ourselves with our seemingly puny muscles. Gravity is so weak because the medium on which it acts, spacetime, is so stiff. And why it acts at arbitrary distance. So stiff that it takes the most extreme event, the collision of black holes, to create barely detectable ripples.
@@infinitemonkey917 I said in theory... Anyway a more useful stuff would be to get gas from planet atmosphere using magnetic fields (Venus titan) to refill spaceship or probe tanks. It seems to me a lot easier than landing, mining, vaporize, and lift off to bring to orbit Of course we would need power... Nuclear reactor. But it is not the video topic. So about any force stronger thant gravity... What can we expect from that in 1000 years from now ?
Seems like extremely advanced aliens might create a gravitational wave beacon. Developing civilizations could then turn their radio telescopes to the beacon and tune in. It would be their way of getting subscribers.😂
@@billboyd4051 Maybe the situation would be similar to the book/movie Contact. They create the beacon to announce their presence in all directions, and we, a civilizations advanced enough to detect the beacon would figure they want to talk and we send a focused high energy radio communications back saying we are interested in talking. After a few thousand years, we get back a radio message that instructs us on how to link up with their network of wormholes or create a hyperspace radio, if such things are really possible. Hopefully they don't call themselves "The Borg".
RAMA spaceships aren't the only linear accelerators that would emit detectable gravitational waves. In a (very rare) head-on collision between two black holes the acceleration of each black hole would be linear. So when LIGO detects this signal, remember "it's never aliens."
@@Heisenberg2A : I partially agree with you: head-on collisions ought to be very rare. But that doesn't mean RAMA-capable aliens are more likely than head-on collisions... perhaps RAMA technology is impossible. (It's never aliens.)
@@brothermine2292 Aliens seem more likely than two arbitrarily small points hitting each other head-on in space. They would need to have literally zero lateral momentum.
@NotHeisenBear : The event horizons are much larger than points, so head-on black hole collisions don't require a collision of two point-like objects. Also, black holes spin, and Penrose calculated the singularity of a spinning black hole is ring-shaped, not a point.
if we had multiple interferometer observatories, with enough distance between them to determine the shape of the wave, as well as the difference in amplitude across the wave, we would be able to determine the source of the wave, cause each of the interactions described will create a wave with a slightly different profile, and with enough sensitivity, it would be possible to determine whether we were seeing a linearly oriented gravitational interaction, or the gravitational equivalent to a sonic boom.
The interesting thing is that such a thing would be trackable, at least to a degree. I mean, depending on how long they are actually accelerating, of course. Even a long shot is worth keeping in our minds.
4:34 WOAH! Mindblown! The gravity waves caused by merging black holes - only mass of our Sun - could be greater than energy of all the light emitted by the stars in the observable universe! That is SERIOUS stuff! Then supermassive black holes merging....
imagine a big space wave pool, maybe they use them for leisure. like instead of water they all hop in their ships and ride generated gravity waves for fun? that'd be cool
Gravitational waves 🌌🌊 could be used for a bunch of things like fast travel, a sensory apparatus, weapons, a by-product of doing something else fancy, etc.
@@laurenpinschannels alcubierre drive types of theories. Thats why he says gravitational waves bcuz your not going faster than the speed of light you're stretching on contracting space itself kinda like making a continuous wormhole. In this case it doesn't violate laws of physics. Yeah you need enormous amounts of energy but were talking about beings that possibly been around much longer than humanity.
Astronomers: "No UFO/UAP's are legit, aliens cant get to Earth, dont be preposterous, i wont look at this nonsense." Also Astronomers: "Could we use gravity waves to detect ET spaceships? How do we detect dyson spheres?" The public: "Ok dude."
“Astronomers: ‘No UFO/UAP's are legit, aliens cant get to Earth…’” - This is changing, fortunately. Many people would call it nonsense, but at the very least not _all._
The odds of ET coming HERE, to Earth, to roam our skies and show us how to pile rocks on top of each other is very low. The odds of ET going from anywhere to anywhere else in a fashion that we might detect is higher. Dyson spheres are much more likely than ET getting around in Jupiter-sized relativistic spaceships.
The video that might very well force a dual purpose for NASA (or similar). Not just signs of life such as microbiology, but a way to implement signs of advanced life. Awesome video!
You got right to the precipice of the point I've been interested in for years. Namely,if a highly advanced civilization wants to communicate they aren't going to opt for electromagnetic waves, but more likely some form of gravitational wave antenna or quantum communications system.. if we're ever going to intercept that communication, we need to assume that they have some clever way of leveraging quantum entanglement or gravitational radiation or some peculiar combination therein. Either way, great episode!!
Of course, begs the question: What would it take to upgrade the current LIGO system so it *could* detect a large ship at a reasonable distance? Assuming we're currently technologically able to do it at all.
There is way to produce gravitation wave with accelerating/decelerating rings. As gravitational wave is basically the oscillation "speed" of time (hard to explain). By creating high speed massive particles within short time creates a fluctuation in space time. Using many such a ring placed next to each other and accelerating particle in the right moments will increase the amplitude of the wave. As the time "speed" is oscillating it could have interesting effects. The major technology challenge is how you transfer the enormous amount of energy required from one ring to the other.
So you’re saying that aliens executing *Rendezvous with RAMAs* to visit a nearby star might-just barely-be detectable through their gravitational waves? ;)
As you mentioned, accelerating in such a way so that we produce gravitational waves just like normal accelerating mass will result in a huuuge loss of energy in these waves. So we can expect a civilization advanced enough to make a spacecraft with mass of Jupiter or a star, able to accelerate to good fraction of speed of sound, is quite likely to find a way to do this without emitting a gravitational wave, like the warp drive you mentioned
Matt, this topic reminded me about the Argus Array from Star Trek. It’s an impressive sub-space telescope that could study all subspace perturbations in the Milky Way. It was so important in Star Trek Universe that it was considered a military target during the Dominion War, because theoretically it could track warp ships through the Galaxy, including the Dominion Fleets. Maybe Ligo and her twins could be the primitive ancestors of some real life versions of the Argus Array. I wonder!
Gravity does NOT follow the inverse square law? 13:33. wow can you do an episode on that. I would think that the expanding surface of the spherical waves from the colliding BH would need to follow the inverse square law. really need this explained please. love your show for this exact reason.
Hearing a scientist say things like "the known warp field solutions" is the best.
it's like the old beer commercial: if you got the stress energy, we got the curvature.
Not to mention "yeeting themselves through the cosmos"
@@jeremyonfire1 that was hilarious
How's it any different if it comes from a character out of DC comics?
@@melaniecampbell7055 it isn't and i love both DC characters and Real Scientists
What Imperium Galactica 2 has taught me is that we need to divert 80% of resources to science for a couple of generations.
YES YES YESSS
Same for Master of Orion.
In other words, the cost of the Extra-Large Hadron Collider.
@@PoorMansChemist man I miss that game.
That means 80% of time towards studying
How fast would I need to flap my arms for LIGO to detect the gravitational waves? If I went from stillness to flapping them at 99% the speed of light, would LIGO detect it?
👍🏻
If you’re flapping, then your arms are still at the top and bottom of every cycle. How many flaps per second can you manage? Hummingbird speed?
I would assume that seismic detectors would be able to do this. Maybe on the other side of planet. Just by friction with air there could be enough energy produced for it to be like dropping a bomb.
XKCD should cover this.
You would need the same acceleration as any other RAMA, so 300 million meters per second squared, or about 30 million times the acceleration of Earth’s gravity at sea level
What a team. Thanks for making the world better.
Travel as fare back in time as time is moving forward
@@osmosisjones4912 Time does not move
So cringe. How are they making the world better lol
@@Beanskiiii Wide-flung cosmic elucidation, duh. A candle in the dark of our demon-haunted world.
@@Beanskiiii They're clearly making his experience of the world better, and they clearly appreciate the compliment. Meanwhile, your horse is so high it shits mountains.
i like how Dr O'Dowd always brings it altogether with the words Space Time at the end of each vid
Always wondered if it was inspired by yes minister/yes prime minister
I like how his elbows always seem to be attached to his torso. He's basically a T-Rex.
Never thought I'd hear about aliens yeeting themselves across the universe at a fraction of the speed of light, hooning about causing wibble wobbling in space time.
Great video, seriously an awesome explanation of LIGO and what it's used for.
The last thing I want to hear from a LIGO person: "That's no moon."
The simulated visuals of black hole mergers always make me do a double take, because the resulting black hole seems so much bigger than it should be. I know why it is: the equation for the Schwarzschild radius of a black hole has the counterintuitive feature of radius scaling *linearly* with mass, in contrast with our everyday experience of fluids with near-constant density and thus *volume* that scales linearly with mass. But seeing that play out in simulated mergers still gives the impression of the sum being much bigger than its parts, rather than the reality that a lot of mass has been lost to gravitational waves.
Because it seems to violate dimensional conservation, as if black holes are 1D. I could understand if black holes scaled like the mass was concentrated in an outer sphere, but instead they act like from the viewer's perspective the mass is concentrated in a circle (edge) instead.
Also seems amazing that gravitational waves dissipate as if space is 2D (1-sphere) rather than going out in a 2-sphere, yet normal gravitation itself goes out in a 2-sphere (3 dimensions). 🤔
@@lyrimetacurl0 Gravitational wave energy still dissipates as 1/distance^2.
entropy goes as the area, so I guess it goes up.
@@tonywells6990 yeah, that threw me for a loop for a while, but I figured out that EM waves are the same way-amplitude goes as 1/r, energy goes as 1/r^2. It’s just a quirk of the fact that we’re almost entirely transparent to gravitational waves, so we can’t build detectors that work like EM wave detectors. And in terms of energy, black hole mergers are unbelievably “bright”; it’s just that we can only interact with that energy in limited ways.
@@moocowpong1 thank you! That was exactly the question I came to the comments looking for an answer to!
As is sometimes the case, some of these concepts have been used in Science Fiction. Joe Haldeman’s “Mindbridge” used such a gravity wave generating space drive for his aliens. Larry Niven’s “Shipstar” was a small planet sized spacecraft that harnessed some of its sun’s output for it’s propulsion. The chuckle inducing bit though, is the term “Rama-craft”. Someone was inspired by Arthur C Clarke’s “Rendezvous With Rama”
It's a really good book, would recommend.
Lol, as soon as I heard the acronym, I came down to find comments about it xD I was like, hey, I remember that book!
And Larry Niven's "The Hole Man" describes an alien communication device that uses small black hole to generate gravitational waves.
_small planet sized spacecraft_
lol i know you meant that it's the size of a small planet, but at first I read that as you saying that a planet-sized spaceship is small 😂
(and who knows, maybe that *is* small somewhere in the universe!)
Also I remember reading a novel from the 60s where the final twist was that quasars have their huge redshift because they are actually stars turned into propulsion devices for their entire solar systems, and advanced alien civilisations leaving the Milky Way galaxy with them, fleeing from some cosmic fate.
Alien: "Oh please. We use worm holes now. Sub-speed-of-light travel is soooo last universe."
Amazing content as always. Not sure if it's just me, but I feel like I actually understood close to 100% of the presentation here, so bravo Dr. Matt!
Yeah this one wasn't too difficult to understand like others lol
Likewise! Great stuff…
True ...im guessing this topic isnt as hatd to grasp as the others...but also well put by Dr. Matt.. Love the 9:08!!!
His specialty is presenting only the information a general audience can understand. If you're really interested, check out the Susskind theoretical minimum series for the next level. And if you're still interested, check out a textbook or an actual class on QM or GR from your local university!
I'm amazed I understood the whole video!
Doesn't happen often.
But they are still very cool to watch.
I love these videos! The part about gravitational waves propagating at the inverse of distance as to distance squared I found especially intriguing.
I always loved physics, and finding Space Time is one of the best things that happened to me. I look forward to every new episode, I usually watch it first thing in the morning (living in Europe it's often to late for me to catch it in the evening), and I literally have an episode playing every time I go to sleep. It's not only interesting, it calms me down, even on the most stressful of days, and there are a lot of those. So I just wanted to say thank you, from the bottom of my heart, for putting so much effort and love into the series. You guys are simply awesome and you enrich my life ❤
That was wholesome AF. Cheers from Canada!
I asked this exact question to Joseph Giaime at LIGO back in 2019. Here is his response:
"It is not thought possible for a civilization with our current or near- to mid-future technical abilities to generate gravitational waves strong enough for us to detect. This is because spacetime is quite stiff, and difficult to significantly excite waves in, by moving things lighter than stars. In fact, it is a standard exercise for Ph.D. students in our field to attempt to design such a presently-impossible 'transmitter.'
For similar reasons, I've never seen a plausible design to use GWs for propulsion.
"
Here was my question:
"
There has been a lot of attention on the "Advanced Aerospace Propulsion" topic of recent, and I'd like to approach some experts in the field of Gravitational Waves via email.
Two silly questions to sip coffee over on a Monday morning:
- Suppose there was a vehicle that operated via producing "Gravitational Waves". Would such a craft be detectable via the Ligo Detectors?
- What is the feasibility of smaller "Hobbyist Grade" detectors?
'
"quite stiff" is the studied understatement of a physics educator - stirring basalt with a paper coffee stirrer is a walk in the park by comparison
I was more than 10 minutes in before I realized that RAMAcraft is almost certainly a reference to Rendezvous With Rama.
Perhaps some Aliens use gravitational waves for communication, their ability to pass through basically anything can be very useful provided you have technology to detect tiny waves.
Aliens 👾👽 are using subquantum waves 🌊 for nearly instant communication. But these are astonishingly advanced 👽.
@@frun That is completely unproven and it would probably be better not to present it like a proven fact
It would be like playing a massively long guitar string and you can play an endless amount of notes on just one string. So I could definitely see it being used for communication.
Maybe they use a combination of gravitational and electromagnetic waves. For instance I could imagine electromagnetic waves getting used for short distance communication and gravitational waves getting used for long distance communication.
You just need to have a way for gravitational waves to express theirselves within a closed system.
I use magnetic nano particles in a meta material configuration to time develop my MRI like images realigning the each pixelated domain
into holographic images of Dark Information Energy reaching forth beyond our spacetime.
Sounds fantastic but fear not 🖖
I have made contact and I don’t know how to tell you this 🤷🏻♂️
They are on their way 🫡
th-cam.com/users/shortsubmkTQ6EyU4?feature=share
Ah, yes. Installing gravitational subspace sensors in Stellaris always feels good! Not as good as the tachyon sensors though...
13:28 It's an apples to oranges comparison -- intensity is amplitude squared. Strain is the gravitational wave amplitude. So you're talking about the 1/r^2 *intensity* decay law for EM waves and comparing it to the 1/r *amplitude* decay law for gravity waves, and then concluding that gravitational waves decay slower.
Good one
Arthur C Clarke still having influence from beyond the grave. A true visionary.
Hate to burst your bubble, but he really was not the first in many of his famous visions and bon-mots. Nor do I think he really pretended to be (although for my money I do think he was a stuck-up self-promoter, but that's just one man's opinion); those of us who knew 50s and 60s sci fi and popular mechanics type publications knew well enough that the stuff predated his, but then in the 90s this odd Arthur C. Clarke myth just slowly too over.
@@DrWhom I’d agree that Asimov was a better science writer and most of Clarkes ideas weren’t novel. But 2001 had a huge influence on me as a child and the philosophical and evolutionary ideas introduced to me still form me today, even directing career paths. I only have to hear also sprach Zarathustra still today and I perceive it is akin to a spiritual experience for a believer in a deity.
@@DrWhom i suspect they are referring to the fact that Arthur C Clarke wrote a series of books about a craft called Rama that was large and could achieve large acceleration (not the scales mentioned in this episode, but still).
5:07 it's funny how he gets a lisp for 1 moment and never has is before or after
i feel my heart skip a beat everytime pbs space time uploads
I can't help but smile when the highly speculative nature of this topic is emphasized. I suspect people get the speculative nature when you are talking about aliens right off the get-go, my friend.
I dunno.
Love how matt is wearing the “it’s never aliens” shirt lol
Neat. Maybe we can find the Puppeteer Fleet of Worlds.
Sick reference, bro.
What's crazy is if we detect such a craft in another galaxy,that species may very well be extinct
That could be. If we do find one it's going to be positively ancient, untold millions of years old. The civilization that built them would've probably collapsed to dust long ago. But that would mean a free planetcraft or attack moon for us if we could somehow get to it.
What makes you think that a civilization that has the abilty to build such tech would be extinct? Lol
Maybe due to speciation or genetic drift. 😮
@@MiguelSedek anything lasting for millions of years is unlikely, but at the very least what we see is garaunteed to no longer exist, like early humans, we've evolved to a point where our past selves are not recognizable
16:18 planet sized spacecraft “hooning” around out there… a great Aussie way to put it
Tremendous how vast the universe is 😳
RAMA ... lol, they are totally trolling everyone. I have the Rama series in my bookshelf, and yes that ship was massive and held entire civilizations as they flew through space as a kind of space ark.
Thank you. Glad someone else caught the reference
I would really like to rendezvous with such a RAMA
I've learned a lot from this video. Lots of facts but the one that stood out to me was that Ligo can triangulate the location of multiple dancing chickens at any given time.
I just want to see a real Alien before i die, come on universe, make it happen 🙏🙏🙏
You are an alien, just for somebody else.
Would it disappoint you it if was just bacteria of some sort?
@@nullbeyondo no it will confirm that life outside earth exists
The AMPLITUDE of electromagnetic and gravitational waves decrease with 1/(distance). The power density decreases with 1/(distance^2) for both. The power of an electromagnetic wave or gravitational wave is proportional to the amplitude squared.
Salutations from Brazil! There are just some months since I found this channel in TH-cam, and it is already my favorite science channel alongside 3B1b, with the advantage of updating more or less regularly. The videos are probably the most precise in TH-cam on advanced physics, and watching them is the nearest experience to reading Feynman’s lectures that anyone may find here.
Fan fact, 3 people in the production of PBS Space Time are from Brazil and 2 from Portugal.
Ooh you would probably like the channel ScienceClicEnglish! They have their videos in other languages too! Such as french and Spanish!
Listening to this in the background at work, and that blackhole noise scared the heck out of me lol
First, props to whoever came up with RAMAcraft. That's a good acronym/reference. Second, I'm really surprised that gravitational waves drop with an inverse law rather than an inverse square. How does that work? I thought that inverse square laws were a natural consequence of the way things expand into 3-dimensional space as 2-d surface.
The energy of gravitational waves do drop with the inverse squared law (like electromagnetism) but it is the 'strain' or amplitude or intensity of the waves that drops as inverse law, same as the amplitude of any wave. The difference is that we detect electromagnetic waves by absorbing their energy in discrete frequencies which are proportional to their energy, via photons. Fortunately for us the way that we detect gravitational waves is based on their amplitude (which is what stretches and compresses spacetime) and not on absorbing their energy.
@14:00, thanks for pointing out the magnitude of the effect has been exaggerated! 😂
If they're anything like us, at least some of their young adults with too much free time have fitted Mega-Grav spoilers on their sportsters to do donuts at 3 AM in a quiet solar system where people need to get up and go to work in the morning!
😂
Yay, unique "no questions" messages are back!
Considering all the reports of our neighbors crafts not producing any sound and that they don't seem to affect more than their immediate surroundings, - it is also quite likely that the craft wouldn't create gravitational wakes at all, or at least not to the extent their mass and acceleration would imply.
This right here.
Reports? There are no reports. Just nutters and liars.
Seen them. They don’t use gravitics.
Yes, they use time. Crafts move relatively slow in space, but they just throw themselves into future/past as needed. From our perspective they move with absurd acceleration.
We always assume astronomical levels of technical and industrial capacity for alien civilizations. But you have to ask, "Why would any society build a planet sized space craft?"
To flee the dark forest before it consumes them.
Why do we always assume aliens will think like we do? Much less build things like we do, or even know our form of math. perhaps they know completely different ways of thinking that would be mind boggling to us.
It's not like we always assume that. We do. But you cannot design an experiment to detect something that we have never thought of. So we are limited to try ideas we humans can think of.
You are quite right, except about maths. (It is maths with an S, you silly American!) The maths is the one thing I know we will have in common with the aliens, as far as the one with the weaker maths goes, barring differences in notation (which can make a big difference).
LISA coming online and us discovering that there's not just signs of Ramacraft out there but lots of them implying a whole galactic civilization and what do we do then is a neat idea for a sci-fi series. :)
Or we turn it on and see nothing but breaking waves approaching the Sol system >_>
Alderaan: You can detect moon sized objects accelerating towards us? Tell me more.
Matt: You need a Jupiter sized ship accelerating at 30% speed of light in a second.
Buster Machine 3: Hold on my beer!
1:44 LOL. Gotta love the full frontal nerdity on display with the name here. Personally I'd have gone with a Heart of Gold reference, except that the full name's too long, the abbreviation is awkward, and that particular ship works by hacking QM, not GR.
Could we detect Deceleration as well? also, how large would a craft have to be within our own star system?
I'm fairly certain anyone accelerating like that _within_ the solar system would be waaaaay more easily detectable with the EM spectrum.
@@emm6064 I mean, yes, but no. What if they're using something other than electricity for their propulsion? some sort of high energy propellent that we have yet to understand, or some bit of physics that we haven't discovered. This *is* a thought experiment after all.
Yes, if conventional then large amounts of energy will have to be ejected in our general direction to counter the existing momentum .
But even if hypothetically FTL, I’d speculate we’d see rather bright streak of Cherenkov Radiation. In all cases where particles can temporarily move at speeds faster than the allowable relative lightspeed of the nearby medium, this emission has occurred. We observe this in isotopic interactions and from neutron stars, where light speed in the areas has been slowed down but the same rules should still apply for something transition from FTL to normal space too.
Rendezvous with Rama - a classic story :)
The idea of a super advanced aliens getting together with their friends doing burnouts was a wonderful image to end on :)
They do put on a great show at times, but their burnouts are silent.
@@billboyd4051 In space, no one can hear you hoon
@@swannie1503 OOOOOOmmmmmmmmmmmm
I'm glad that this is a topic that science is capable of taking reasonably seriously. Regardless of whatever alien life may or may not be out there for us to find, thought experiments like this are valuable and useful because they encourage us to constantly seek out new ideas of things to look for and how to see them. It's like militaries and disaster response agencies considering how they would respond to scenarios like "zombie apocalypse."
One of the most understandable episodes. Thanks.
Lisa & Ligo song - to tune of A Few of my Favourite things.
LIGO did land based,
and LISA is in space.
Little gold cubes,
floating free in a space ship.
One day we'll find out if
gravitational waves,
can be low frequency
and also high!
LIGO land bound,
LISA space bound
cubes floating free.
Science is great,
and science is good
Knowledge for you; and me. :)
If a RAMACraft was accelerating with that much energy inside our galaxy, wouldn't we see it with more traditional methods?
Well I guess it would depend on how far it was away. Like he said the main thing about other signals is that they fall off with a lot greater strength compared to gravity
That depends if it's accelerating through a nebula or through empty space. If it's accelerating inside a nebula it will compress the stellar gas in front of it immensely causing it to glow and maybe even forming a new star or two.
@@killman369547 you assume it is coming straight at us, if not, the engine exhaust should easily be visible
12:34 It's actually really interesting that the sensitivity to detect gravitational waves decreases linearly with distance instead of with the square of the distance like detecting light. Just on the face of it you would think that gravitational wave detectors would be subject to the same inverse square law, but as touched on briefly in the video telescopes measure the "intensity" of light while gravitational wave detectors are measuring the "amplitude" of the waves, not the intensity. And while intensity dissipates according to the inverse square law, the amplitude of waves does not. Or to put it another way, intensity of these waves is a function of the square of the amplitude, so since intensity dissipates using an inverse square law it follows that amplitude dissipates as a linear function of distance instead.
(As an aside this is also, from what I can tell, true for sound waves, for instance. Our eardrums detect the intensity of sound waves, which disperse using an inverse square law. But if you want to emulate a similar effect in digital audio you need to adjust the amplitude of the wave linearly to make it "sound" like it's that same distance away to your ear.)
Honestly the relationship between intensity and amplitude and the inverse square law could be an interesting topic for a future video maybe, just a thought.🙂
That's because we are probably living in a simulation. Hello fellow NPC!
Are you accounting for the logarithmic nature of sound perception?
@@michaelmicek Not specifically no. I'm simply talking about how the energy of a wave is proportional to the square of its amplitude. Since energy dissipates with the square of the distance that means the amplitude dissipates linearly with the distance.
“Gravity is the weakest force”
“One pair of merging black holes radiate more power than all the visible light radiated by all the stars in the visible universe”
Has gravity is the weakest force, and for instance magnetic force is a lot stronger. In theory, a huge magnetic field may be able to 'extract' mater from a back hole ?
Or closer to us : using magnetic field, we could extract mater/gaz from Venus or Jupiter atmosphere from far enough away (for any purpose such as fulling ship tank for instance). Gaz that could be later used in a ion like engine
@@bernardsegonnes1335 Gravity is the weakest force (smallest coupling constant), but the masses involved are very large...
What is holding matter (or whatever is left) inside an event horizon is not a 'force'; it's the fact that spacetime is moving 'inwards' faster than the speed of light.
Yes, gravity is the weakest force. Bugs barely notice it. We routinely win against it by lifting anything or ourselves with our seemingly puny muscles.
Gravity is so weak because the medium on which it acts, spacetime, is so stiff. And why it acts at arbitrary distance. So stiff that it takes the most extreme event, the collision of black holes, to create barely detectable ripples.
@@bernardsegonnes1335 How do you plan to extract something from beyond the event horizon where nothing can escape ? Invent new physics I suppose.
@@infinitemonkey917 I said in theory...
Anyway a more useful stuff would be to get gas from planet atmosphere using magnetic fields (Venus titan) to refill spaceship or probe tanks. It seems to me a lot easier than landing, mining, vaporize, and lift off to bring to orbit
Of course we would need power... Nuclear reactor.
But it is not the video topic. So about any force stronger thant gravity... What can we expect from that in 1000 years from now ?
Videos about aliens are my favorite.
Matt is here to tell us to expect the aliens to come in from a direction we're not currently watching in
Now we just need to start planning for a rendevous with RAMA - craft.
Seems like extremely advanced aliens might create a gravitational wave beacon. Developing civilizations could then turn their radio telescopes to the beacon and tune in. It would be their way of getting subscribers.😂
For a civilization to develop, it must first stop shooting each other, out of fear, greed, racism, hatred and religious beliefs.
clickbait 😁
Actually true though
The time delay still exists, a very long delay.
@@billboyd4051 Maybe the situation would be similar to the book/movie Contact. They create the beacon to announce their presence in all directions, and we, a civilizations advanced enough to detect the beacon would figure they want to talk and we send a focused high energy radio communications back saying we are interested in talking. After a few thousand years, we get back a radio message that instructs us on how to link up with their network of wormholes or create a hyperspace radio, if such things are really possible. Hopefully they don't call themselves "The Borg".
At 15:29 the proper expression (especially in this context) is "on the gripping hand".
RAMA spaceships aren't the only linear accelerators that would emit detectable gravitational waves. In a (very rare) head-on collision between two black holes the acceleration of each black hole would be linear. So when LIGO detects this signal, remember "it's never aliens."
I'm guessing aliens would be more likely. An aligned, head-on collision, of tiny radius singularities seems nearly impossible.
@@Heisenberg2A : I partially agree with you: head-on collisions ought to be very rare. But that doesn't mean RAMA-capable aliens are more likely than head-on collisions... perhaps RAMA technology is impossible. (It's never aliens.)
That is essentially the conclusion to the video...
@@brothermine2292 Aliens seem more likely than two arbitrarily small points hitting each other head-on in space. They would need to have literally zero lateral momentum.
@NotHeisenBear : The event horizons are much larger than points, so head-on black hole collisions don't require a collision of two point-like objects.
Also, black holes spin, and Penrose calculated the singularity of a spinning black hole is ring-shaped, not a point.
5:45 aliens yeeting themselves got me cracking up 🤣🤣
me too, this came to my mind while i was thinking about the sentence :) : th-cam.com/video/nNTVzwjEyb4/w-d-xo.html
Three Body Problem series readers: _flashbacks_
if we had multiple interferometer observatories, with enough distance between them to determine the shape of the wave, as well as the difference in amplitude across the wave, we would be able to determine the source of the wave, cause each of the interactions described will create a wave with a slightly different profile, and with enough sensitivity, it would be possible to determine whether we were seeing a linearly oriented gravitational interaction, or the gravitational equivalent to a sonic boom.
The interesting thing is that such a thing would be trackable, at least to a degree. I mean, depending on how long they are actually accelerating, of course. Even a long shot is worth keeping in our minds.
It would be scary if it was on Earth 🌍. 😱😱😱
@@UniDocs_Mahapushpa_Cyavana Well, I'm only talking about detecting. It's clearly not an effective means of travel.
@@silversonic1 Detecting such a thing on Earth 🌍 *is* the scary 😱 part.
Damn, the first second of of the spiriling black hole sound triggered me as I though my cockapoo was barking. Do I need help? 🤣🤣
It's aliens, I knew it.
4:34 WOAH! Mindblown! The gravity waves caused by merging black holes - only mass of our Sun - could be greater than energy of all the light emitted by the stars in the observable universe! That is SERIOUS stuff! Then supermassive black holes merging....
imagine a big space wave pool, maybe they use them for leisure. like instead of water they all hop in their ships and ride generated gravity waves for fun? that'd be cool
An ultralight spaceship, batteries not included.
Why is strain a linear decay while flux decays at inverse square
Gravitational waves 🌌🌊 could be used for a bunch of things like fast travel, a sensory apparatus, weapons, a by-product of doing something else fancy, etc.
Not by any means we can conceive of.
Gravitational Sonic BOOM = Aftermath of Authentic 2 lb Mexican Burrito. Because.... SCIENCE!
There is of course the chance that the aliens design some kind of 'gravitational wave suppressor' in order to make their ships undetectable.
do we have any hint of an inkling of physics that would permit this?
That requires them wanting to hide from other aliens 👽.
Yeah, a warp bubble. Even mentioned in the video. But they’d still need negative mass and an ungodly amount of energy.
maybe they use two faze gravity anti gravity and gravity to pinball there way around the galaxy. They are pretty smart critters.
@@laurenpinschannels alcubierre drive types of theories. Thats why he says gravitational waves bcuz your not going faster than the speed of light you're stretching on contracting space itself kinda like making a continuous wormhole. In this case it doesn't violate laws of physics. Yeah you need enormous amounts of energy but were talking about beings that possibly been around much longer than humanity.
It's ok, Rama spacecrafts always come in threes so we get a few shots at detecting them.
If we find aliens, it will probably be a repeat of Avatar where a human betrays mankind to clap an alien
I volunteer myself as tribute
I would for sure be that guy
Or worse, the ETO from Three Body Problem/Dark Forest
If we find aliens, they sure AF won't look anything like us.
thanks Matt, your show de-stresses my day.
Astronomers: "No UFO/UAP's are legit, aliens cant get to Earth, dont be preposterous, i wont look at this nonsense."
Also Astronomers: "Could we use gravity waves to detect ET spaceships? How do we detect dyson spheres?"
The public: "Ok dude."
“Astronomers: ‘No UFO/UAP's are legit, aliens cant get to Earth…’” - This is changing, fortunately. Many people would call it nonsense, but at the very least not _all._
The odds of ET coming HERE, to Earth, to roam our skies and show us how to pile rocks on top of each other is very low. The odds of ET going from anywhere to anywhere else in a fashion that we might detect is higher. Dyson spheres are much more likely than ET getting around in Jupiter-sized relativistic spaceships.
@@CarFreeSegnitz Don't spill the beans!!!
@@CarFreeSegnitz They are here already, and if you take the time to watch the skies you can see them.
@@billboyd4051 Don't you need to snort a copious amount of drugs to see them though?
I WANT THAT T-SHIRT!!!!
Never mind. All is well. I bought it.
The video that might very well force a dual purpose for NASA (or similar). Not just signs of life such as microbiology, but a way to implement signs of advanced life.
Awesome video!
Rendezvous with Rama is unironically a fantastic science fiction book about a huge mysterious object entering the solar system.
You got right to the precipice of the point I've been interested in for years. Namely,if a highly advanced civilization wants to communicate they aren't going to opt for electromagnetic waves, but more likely some form of gravitational wave antenna or quantum communications system.. if we're ever going to intercept that communication, we need to assume that they have some clever way of leveraging quantum entanglement or gravitational radiation or some peculiar combination therein. Either way, great episode!!
I wonder if the authors were also interested in plotting the Rendezvous with RAMA craft.
If it passes peer review, it's quite a step-up for science fiction.
You could literally detect the deathstar from everywhere. Lots of lives could've been saved.
Of course, begs the question: What would it take to upgrade the current LIGO system so it *could* detect a large ship at a reasonable distance? Assuming we're currently technologically able to do it at all.
Ripples in space time, what a concept : )
There is way to produce gravitation wave with accelerating/decelerating rings. As gravitational wave is basically the oscillation "speed" of time (hard to explain). By creating high speed massive particles within short time creates a fluctuation in space time. Using many such a ring placed next to each other and accelerating particle in the right moments will increase the amplitude of the wave.
As the time "speed" is oscillating it could have interesting effects.
The major technology challenge is how you transfer the enormous amount of energy required from one ring to the other.
the thought of our entire planet "wobbling wobbling a bit" is all but comforting
So you’re saying that aliens executing *Rendezvous with RAMAs* to visit a nearby star might-just barely-be detectable through their gravitational waves? ;)
As you mentioned, accelerating in such a way so that we produce gravitational waves just like normal accelerating mass will result in a huuuge loss of energy in these waves. So we can expect a civilization advanced enough to make a spacecraft with mass of Jupiter or a star, able to accelerate to good fraction of speed of sound, is quite likely to find a way to do this without emitting a gravitational wave, like the warp drive you mentioned
I do look forward to when spaceX reveals their interplanetary "yeet" drive.
On behalf of the LISA Social Media team ... thanks for remembering us.
4:13 Perfect opportunity for a “yo mama” joke
You missed a perfect opportunity to say "on the gripping hand"!
Great video
Matt, this topic reminded me about the Argus Array from Star Trek.
It’s an impressive sub-space telescope that could study all subspace perturbations in the Milky Way.
It was so important in Star Trek Universe that it was considered a military target during the Dominion War, because theoretically it could track warp ships through the Galaxy, including the Dominion Fleets.
Maybe Ligo and her twins could be the primitive ancestors of some real life versions of the Argus Array.
I wonder!
Alderaan is looking forward LIGO
@@XimCines, I believe that it’s a little late for Alderaan. Hahahahaha…
I suppose that Star Wars doesn’t apply time travel to save the planet.
Then look for Buster Machine 3. 😊
A Jupiter sized vessel, the use of such a mounstruosity I won't tell to avoid spoilers.
Surely they would mask their trails when they could
Yeeting themselves through the cosmos. I too, am a fellow young person, how do you do my dude? 😂 I'm just kidding I also have a young one.
Rama craft? Love it. Arthur c Clark still working from beyond the grave, lol.
This reminds me of the three body problem series
Hide well, cleanse well.
Gravity does NOT follow the inverse square law? 13:33. wow can you do an episode on that. I would think that the expanding surface of the spherical waves from the colliding BH would need to follow the inverse square law. really need this explained please. love your show for this exact reason.
I think Gene Roddenberry is a time traveler.
I like how they incorporated Rama 😊
I hope they use the word 'yeet' in the paper