7 ms·

The first gravitational wave detected (GW150914 in 2015) was from a collision 1.3 billion years away. IIRC ~5 Solar masses was converted into energy in a matter

by cletus 2y ago

The first gravitational wave detected (GW150914 in 2015) was from a collision 1.3 billion years away. IIRC ~5 Solar masses was converted into energy in a matter of seconds. This is a mind-bogglingly large energy event. Yet to detect is LIGO has to be unbelievably sensitive. I've heard it described as measuring the distance to Alpha Centauri with the variation of the width of a human hair. I still don't believe warp drives (in this case Alcubierre drive [1] isn't viable. It's an exercise in hopium. People want to live in Star Trek or Star Wars so want it to be true. It's an object lesson in not understanding the domain of a function. Warp drive concepts rely on concepts like negative mass and/or energy. I can plug negative (or even complex) numbers into quantities like velocity or acceleration but again I've just violated the function domain even though various formulas will spit out (nonsencial) values. Garbage in, garbage out. But let's just say this is possible (which, again, IMHO it isn't), then we get to the energy budget required for any of these FTL concepts. The amount of energy to reach even our nearest stellar neighbour is mind-bogglingly large. Some estimates I've seen for various warp drive concepts involve things like 1 Solar mass of energy. [1]: https://en.wikipedia.org/wiki/Alcubierre_drive https://en.wikipedia.org/wiki/Alcubierre_drive

canada_engineer 2y ago
Its negativity like this that holds us back.
- guerrilla 2y ago
  It may or may not be. It's negative like that that holds us back from finding out whether it's possible or not though.
  - oopsallmagic 2y ago
    [flagged]
  - oopsallmagic 2y ago
    [dead]
- hdivider 2y ago
  On HN, comments meant to stimulate optimism and willpower don't tend to get encouraged. Cynicism, skepticism, figuring out how things will fail -- as they inevitably will, of course -- or how if they succeed, they're corrupt or broken in some way...that is increasingly the coin of the realm here. :) In reality, your sentiment is correct. Sure, there are laws of physics. But they are also unknown, as the ones humans understand don't describe all observed phenomena by a long shot. There are still restrictions even so, but incredible unknowns await us. As they always have. What engineering-minded folks frequently don't understand is the need to apply sheer old willpower, after using all that intellect. Ending with a positive, with the notion that it can be done; we just have to figure out how.
  - Zenzero 2y ago
    The unfortunate thing is many people seem to equate cynicism with demonstration of intelligence. While you generally need to be smart to come up with reasons why something might not work, it becomes a lazy way of thinking. Experience in life has taught me that it is far simpler to sit back and poke holes in things than to construct something new.
    - hdivider 2y ago
      Indeed! And as a European, I find it even more curious when Americans take this more cynical stance. I mean, what have we come to, when a European will go and take a risk, for a chance at an awesome discovery, and an American dare not? ;) The explorers who first went sailed into the deep Atlantic, with unknown seas and lands beyond, were full of doubts too -- but they did it anyway. Because they had to. In our time, we humans have to continually rekindle our explorer spirit, no matter how settled or distraught our ambient culture becomes. We must explore, with optimism and willpower -- and yes, with plenty of intellect and skepticism too, but end with optimism -- precisely in order to solve the actual problems our world faces.
    - somenameforme 2y ago
      It also works better for people's egos. Saying and trying things that might end up being wrong means a willingness to not only accept failure, but failure that might end up making you look stupid. By contrast appeal to 'what everybody knows' in a given time and you can never be wrong. Because even when you are wrong it can easily be hand-waved away as, once again, 'well everybody thought...' Though, thankfully for humanity - not "everybody"!
ceejayoz 2y ago
You might be right. You might be making a very old mistake. https://en.wikipedia.org/wiki/Flying_Machines_Which_Do_Not_Fly https://en.wikipedia.org/wiki/Flying_Machines_Which_Do_Not_F...
- osigurdson 2y ago
  Agree, but I suspect at that time the opinions regarding the impossibility of flight, though popular, must have been highly uninformed. There were no violations of long established physics to achieve flight, "only" engineering challenges to make it possible. I still don't see any point in claiming that a given thing can never be done. What does it help? Our knowledge of the universe isn't complete and I don't think people are starving because others are thinking about warp drives.
  - csunbird 2y ago
    Plus, there were live examples of stuff flying around (birds). I do not see anything going FTL anywhere right now.
    - snowwrestler 2y ago
      > I do not see anything going FTL anywhere right now. Yes, well, you wouldn’t see it, would you?
      - SideburnsOfDoom 2y ago
        You would see it soon. Too soon. https://www.goodreads.com/quotes/672472-there-was-a-young-lady-named-bright-whose-speed-was https://www.goodreads.com/quotes/672472-there-was-a-young-la...
    - vardump 2y ago
      > I do not see anything going FTL anywhere right now. Other than distant galaxies from each other.
throwaway63467 2y ago
Not even 100 years ago computers could do a few operations per second, today you can put a 100,000,000,000,000 operations per seconds computer in you pocket. I agree though that Alcubierre drive is probably a dud, no one with serious physics education takes that as a real possibility, there are always some crackpots but seeing the math and looking at the standard model it’s very unlikely such a thing exists. Close to speed of light travel is probably good enough though, people are hung up on the idea humans will take to the stars but that’s just very unlikely. AI on the other hand seems almost plausible with our current technological basis already.
- hcarvalhoalves 2y ago
  > Not even 100 years ago computers could do a few operations per second, today you can put a 100,000,000,000,000 operations per seconds computer in you pocket. These computers still obey the same fundamentals though, in fact we’ll reach the Moore limit soon and it’ll take a breakthrough to advance further. Steady progress inside what’s possible is different than the argument of OP about the physics of WD being fundamentally flawed.
  - throwaway63467 2y ago
    Theory of low-dimensional semiconductors and many other theories underlying modern computers were largely incomplete or non-existent 100 years ago, general relativity isn’t that old either and there are substantial gaps in the extremes (e.g. huge masses/curvatures on the quantum scale), there’s definitely stuff lurking there waiting to be discovered. Just because we kno a lot doesn’t mean we know everything, there are ridiculous gaps in our understanding e.g. mass-energy density of the universe, I expect our understanding of the world to fundamentally change again this century, maybe more than once.
  - somenameforme 2y ago
    Just expanding on a peer comment in a different direction, but no - modern computers are fundamentally different. Earlier computers used relatively simple vacuum tubes for switches. Imagining billions of these fitting in your pocket, let alone being able to be powered by a tiny battery, would have seemed completely nonsensical. Modern computing required the development of entirely new technology that people had no real reason to think would ever exist. The Golden Age sci-fi got so much right, yet basically nobody predicted miniaturization on anything like the scale we achieved. Because they wanted to remain within the domain hard sci-fi, and not what would have been perceived as fantasy at the time.
somenameforme 2y ago
And would you not say that this pessimism is a recurring theme in humanity? In 1903 the NYTimes predicted that human flight would be impossible, that it's been a complete waste of resources to pursue - resources that could be put to much better and realistic use elsewhere, and that it was ultimately a childish fantasy. They had typically great timing as it was only 9 weeks later than the Wright Bros completed their inaugural flight. Then once it was completed they insisted it was pointless anyhow, because it would only ever be possible for but a handful of rich elites to actually utilize. By 1920 they'd be back boldly claiming that human spaceflight would be impossible. This time with even more scorn, mockery, and appeal to expertise: "That [rocket pioneer Robert] Goddard… does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react — to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high schools." [2] Everybody with a basic knowledge of Newtonian laws knows you need something to react against to move, and there's nothing in space to react against. What imbeciles to think otherwise! The problem we face is that it's impossible to meaningfully predict the future when there may yet remain many revolutionary or otherwise unimaginable discoveries yet to be made. In general I see room for extreme optimism because in terms of basic knowledge of the universe we knew next to nothing but a century ago. And we remain a people stranded on a single planet relying on imprecise limited instrumentation, lots of assumptions, and some math to try to figure out what's happening in the other 99.999999999% (one should add quite a few more nines there) of the universe. To assume we've just figured it all out in this century seems improbable, to put it very mildly. [1] - https://bigthink.com/pessimists-archive/air-space-flight-impossible/ https://bigthink.com/pessimists-archive/air-space-flight-imp... [2] - https://www.vice.com/en/article/kbzd3a/the-new-york-times-1920-editorial-mocking-space-travel-remains-a-classic https://www.vice.com/en/article/kbzd3a/the-new-york-times-19...
- kiba 2y ago
  All these people didn't make a prediction based on physics. Of course, it also doesn't help if you misunderstand physics. Physics will determine a lot of what's actually possible and not possible to build, and there's a lot of things we could build even without FTL. FTL is understood as mostly impossible because it violates causality.
deleted 2y ago
[deleted]
MattPalmer1086 2y ago
There are now positive energy soliton solutions to the warp drive[1] Still not exactly practical, but one less fundamental problem to solve. [1] https://arxiv.org/abs/2201.00652 https://arxiv.org/abs/2201.00652
- cletus 2y ago
  I'm aware of this proposal and it's really just as impractical. More detail [1]. [1]: https://www.scientificamerican.com/article/star-treks-warp-drive-leads-to-new-physics/ https://www.scientificamerican.com/article/star-treks-warp-d...
osigurdson 2y ago
I think we have all plugged v > c into 1 / sqrt (1 - v^2 / c^2) and observed that the math works but aren't clear about what it means. However, I feel our understanding of the universe is not nearly complete. There may be ways to travel > c, we may discover them or we may not.
- cletus 2y ago
  Forgive me if I get this wrong as I'm exceeding the limits of my physics knowledge here but what you're talking about sounds like what I would call a special relativity model of thinking. The general relativity model is where everything has a constant spacetime velocity vector. So time dilation just expresses that higher velocity through space necessarily lowers time "velocity". So the special relativity view is to think of a straight line as the shortest distance between two points where the general relativity view is the longest proper time between two events in spacetime. So if we're just going to talk about velocity through space (rather than a constant spacetime velocity), it's best to think of velocity as a value with domain [0,c] rather than an unbounded real number because that's what we're used to dealing with.
otikik 2y ago
> The amount of energy to reach even our nearest stellar neighbour is mind-bogglingly large. Some estimates I've seen for various warp drive concepts involve things like 1 Solar mass of energy. Nothing a couple Dilithium crystals can't solve.
- paulkrush 2y ago
  From the article:"In other words, it’s a long shot—but that’s always the case when it comes to faster-than-light ravel."
- ido 2y ago
  I believe it’s matter/anti-matter reaction that provides the energy and the dilithium simply regulates the process.
Amezarak 2y ago
> . People want to live in Star Trek or Star Wars so want it to be true. I think it's more than just wanting it: a century of scifi has convinced people that "cheap" (in terms of energy and time dilation) FTL travel does exist and we just have to figure it out, when there's no a priori reason to think so at all. The same with most other aspects of space travel. There's no reason to believe anything recognizably human will be engaging in interstellar space travel, and if it's not human, I personally don't care. I don't feel some sort of religious mandate to invent machines or bioengineered entities to take over the universe. We've really underestimated the power of media programming.
throwawaymaths 2y ago
Probably worth mentioning that to date (IIRC) this is the only gravitational wave observed that correlates with an em spectrum event. Which seems super weird. Yes, I'm suggesting LIGO might be a scam. (The pulsar timing network seems solid, though).

by cletus 2y ago

canada_engineer 2y ago

Its negativity like this that holds us back.

guerrilla 2y ago
It may or may not be. It's negative like that that holds us back from finding out whether it's possible or not though.
- oopsallmagic 2y ago
  [flagged]
- oopsallmagic 2y ago
  [dead]
hdivider 2y ago
On HN, comments meant to stimulate optimism and willpower don't tend to get encouraged. Cynicism, skepticism, figuring out how things will fail -- as they inevitably will, of course -- or how if they succeed, they're corrupt or broken in some way...that is increasingly the coin of the realm here. :) In reality, your sentiment is correct. Sure, there are laws of physics. But they are also unknown, as the ones humans understand don't describe all observed phenomena by a long shot. There are still restrictions even so, but incredible unknowns await us. As they always have. What engineering-minded folks frequently don't understand is the need to apply sheer old willpower, after using all that intellect. Ending with a positive, with the notion that it can be done; we just have to figure out how.
- Zenzero 2y ago
  The unfortunate thing is many people seem to equate cynicism with demonstration of intelligence. While you generally need to be smart to come up with reasons why something might not work, it becomes a lazy way of thinking. Experience in life has taught me that it is far simpler to sit back and poke holes in things than to construct something new.
  - hdivider 2y ago
    Indeed! And as a European, I find it even more curious when Americans take this more cynical stance. I mean, what have we come to, when a European will go and take a risk, for a chance at an awesome discovery, and an American dare not? ;) The explorers who first went sailed into the deep Atlantic, with unknown seas and lands beyond, were full of doubts too -- but they did it anyway. Because they had to. In our time, we humans have to continually rekindle our explorer spirit, no matter how settled or distraught our ambient culture becomes. We must explore, with optimism and willpower -- and yes, with plenty of intellect and skepticism too, but end with optimism -- precisely in order to solve the actual problems our world faces.
  - somenameforme 2y ago
    It also works better for people's egos. Saying and trying things that might end up being wrong means a willingness to not only accept failure, but failure that might end up making you look stupid. By contrast appeal to 'what everybody knows' in a given time and you can never be wrong. Because even when you are wrong it can easily be hand-waved away as, once again, 'well everybody thought...' Though, thankfully for humanity - not "everybody"!

ceejayoz 2y ago

You might be right. You might be making a very old mistake. https://en.wikipedia.org/wiki/Flying_Machines_Which_Do_Not_Fly https://en.wikipedia.org/wiki/Flying_Machines_Which_Do_Not_F...

osigurdson 2y ago
Agree, but I suspect at that time the opinions regarding the impossibility of flight, though popular, must have been highly uninformed. There were no violations of long established physics to achieve flight, "only" engineering challenges to make it possible. I still don't see any point in claiming that a given thing can never be done. What does it help? Our knowledge of the universe isn't complete and I don't think people are starving because others are thinking about warp drives.
- csunbird 2y ago
  Plus, there were live examples of stuff flying around (birds). I do not see anything going FTL anywhere right now.
  - snowwrestler 2y ago
    > I do not see anything going FTL anywhere right now. Yes, well, you wouldn’t see it, would you?
    - SideburnsOfDoom 2y ago
      You would see it soon. Too soon. https://www.goodreads.com/quotes/672472-there-was-a-young-lady-named-bright-whose-speed-was https://www.goodreads.com/quotes/672472-there-was-a-young-la...
  - vardump 2y ago
    > I do not see anything going FTL anywhere right now. Other than distant galaxies from each other.

throwaway63467 2y ago

Not even 100 years ago computers could do a few operations per second, today you can put a 100,000,000,000,000 operations per seconds computer in you pocket. I agree though that Alcubierre drive is probably a dud, no one with serious physics education takes that as a real possibility, there are always some crackpots but seeing the math and looking at the standard model it’s very unlikely such a thing exists. Close to speed of light travel is probably good enough though, people are hung up on the idea humans will take to the stars but that’s just very unlikely. AI on the other hand seems almost plausible with our current technological basis already.

hcarvalhoalves 2y ago
> Not even 100 years ago computers could do a few operations per second, today you can put a 100,000,000,000,000 operations per seconds computer in you pocket. These computers still obey the same fundamentals though, in fact we’ll reach the Moore limit soon and it’ll take a breakthrough to advance further. Steady progress inside what’s possible is different than the argument of OP about the physics of WD being fundamentally flawed.
- throwaway63467 2y ago
  Theory of low-dimensional semiconductors and many other theories underlying modern computers were largely incomplete or non-existent 100 years ago, general relativity isn’t that old either and there are substantial gaps in the extremes (e.g. huge masses/curvatures on the quantum scale), there’s definitely stuff lurking there waiting to be discovered. Just because we kno a lot doesn’t mean we know everything, there are ridiculous gaps in our understanding e.g. mass-energy density of the universe, I expect our understanding of the world to fundamentally change again this century, maybe more than once.
- somenameforme 2y ago
  Just expanding on a peer comment in a different direction, but no - modern computers are fundamentally different. Earlier computers used relatively simple vacuum tubes for switches. Imagining billions of these fitting in your pocket, let alone being able to be powered by a tiny battery, would have seemed completely nonsensical. Modern computing required the development of entirely new technology that people had no real reason to think would ever exist. The Golden Age sci-fi got so much right, yet basically nobody predicted miniaturization on anything like the scale we achieved. Because they wanted to remain within the domain hard sci-fi, and not what would have been perceived as fantasy at the time.

somenameforme 2y ago

And would you not say that this pessimism is a recurring theme in humanity? In 1903 the NYTimes predicted that human flight would be impossible, that it's been a complete waste of resources to pursue - resources that could be put to much better and realistic use elsewhere, and that it was ultimately a childish fantasy. They had typically great timing as it was only 9 weeks later than the Wright Bros completed their inaugural flight. Then once it was completed they insisted it was pointless anyhow, because it would only ever be possible for but a handful of rich elites to actually utilize. By 1920 they'd be back boldly claiming that human spaceflight would be impossible. This time with even more scorn, mockery, and appeal to expertise: "That [rocket pioneer Robert] Goddard… does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react — to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high schools." [2] Everybody with a basic knowledge of Newtonian laws knows you need something to react against to move, and there's nothing in space to react against. What imbeciles to think otherwise! The problem we face is that it's impossible to meaningfully predict the future when there may yet remain many revolutionary or otherwise unimaginable discoveries yet to be made. In general I see room for extreme optimism because in terms of basic knowledge of the universe we knew next to nothing but a century ago. And we remain a people stranded on a single planet relying on imprecise limited instrumentation, lots of assumptions, and some math to try to figure out what's happening in the other 99.999999999% (one should add quite a few more nines there) of the universe. To assume we've just figured it all out in this century seems improbable, to put it very mildly. [1] - https://bigthink.com/pessimists-archive/air-space-flight-impossible/ https://bigthink.com/pessimists-archive/air-space-flight-imp... [2] - https://www.vice.com/en/article/kbzd3a/the-new-york-times-1920-editorial-mocking-space-travel-remains-a-classic https://www.vice.com/en/article/kbzd3a/the-new-york-times-19...

kiba 2y ago
All these people didn't make a prediction based on physics. Of course, it also doesn't help if you misunderstand physics. Physics will determine a lot of what's actually possible and not possible to build, and there's a lot of things we could build even without FTL. FTL is understood as mostly impossible because it violates causality.

deleted 2y ago

[deleted]

MattPalmer1086 2y ago

There are now positive energy soliton solutions to the warp drive[1] Still not exactly practical, but one less fundamental problem to solve. [1] https://arxiv.org/abs/2201.00652 https://arxiv.org/abs/2201.00652

cletus 2y ago
I'm aware of this proposal and it's really just as impractical. More detail [1]. [1]: https://www.scientificamerican.com/article/star-treks-warp-drive-leads-to-new-physics/ https://www.scientificamerican.com/article/star-treks-warp-d...

osigurdson 2y ago

I think we have all plugged v > c into 1 / sqrt (1 - v^2 / c^2) and observed that the math works but aren't clear about what it means. However, I feel our understanding of the universe is not nearly complete. There may be ways to travel > c, we may discover them or we may not.

cletus 2y ago
Forgive me if I get this wrong as I'm exceeding the limits of my physics knowledge here but what you're talking about sounds like what I would call a special relativity model of thinking. The general relativity model is where everything has a constant spacetime velocity vector. So time dilation just expresses that higher velocity through space necessarily lowers time "velocity". So the special relativity view is to think of a straight line as the shortest distance between two points where the general relativity view is the longest proper time between two events in spacetime. So if we're just going to talk about velocity through space (rather than a constant spacetime velocity), it's best to think of velocity as a value with domain [0,c] rather than an unbounded real number because that's what we're used to dealing with.

otikik 2y ago

> The amount of energy to reach even our nearest stellar neighbour is mind-bogglingly large. Some estimates I've seen for various warp drive concepts involve things like 1 Solar mass of energy. Nothing a couple Dilithium crystals can't solve.

paulkrush 2y ago
From the article:"In other words, it’s a long shot—but that’s always the case when it comes to faster-than-light ravel."
ido 2y ago
I believe it’s matter/anti-matter reaction that provides the energy and the dilithium simply regulates the process.

Amezarak 2y ago

> . People want to live in Star Trek or Star Wars so want it to be true. I think it's more than just wanting it: a century of scifi has convinced people that "cheap" (in terms of energy and time dilation) FTL travel does exist and we just have to figure it out, when there's no a priori reason to think so at all. The same with most other aspects of space travel. There's no reason to believe anything recognizably human will be engaging in interstellar space travel, and if it's not human, I personally don't care. I don't feel some sort of religious mandate to invent machines or bioengineered entities to take over the universe. We've really underestimated the power of media programming.

throwawaymaths 2y ago

Probably worth mentioning that to date (IIRC) this is the only gravitational wave observed that correlates with an em spectrum event. Which seems super weird. Yes, I'm suggesting LIGO might be a scam. (The pulsar timing network seems solid, though).