The Absurdity of Detecting Gravitational Waves (2017) [video]
youtube.com
youtube.com
One of my favorite videos is on his alternate channel, 2veritasum. Survivor Bias: https://www.youtube.com/watch?v=_Qd3erAPI9w
He recently made a full length movie:
It’s an awesome experiment. And it requires huge computational resources to process all the data they take in.
I wonder this because it occurs to me that one possible answer to Fermi's paradox is that aliens don't use Radio or other EM to chat.
And maybe they don't leak it because they move energy and information around more efficiently than we do.
Separating something from noise is a challenge on itself especially if signals are compressed or encrypted
And the most disappointing/intriguing part is there's a good chance humanity will never, ever know the answers and will never have any confirmation or denial of any of those possibilities. Or if they do, it might be so far into the future that humanity as a concept will cease to exist. The universe is just too big.
But then it struck me, maybe there will be one advantage, EM can be absorbed, blocked and warped while gravitational waves are not affected by anything, thus guaranteed to deliver the message(?)
...But man-made gravitational waves are, without some scientific advance eclipsing the discovery of electricity, completely beyond any human capability of being produced at the levels required for extra terrestrial communication.
Wait, what? How? The wavefront still spreads out over the quadratically increasing surface of a sphere, right, just like EM waves?
https://en.wikipedia.org/wiki/Inverse-square_law#Gravitation
If you like that sort of sci-fi, read the book; it's worth it !
Of course for us we’d never detect those point to point transmissions unless we were incredibly lucky to be along the vector between two aliens communicating.
At first glance, this seems to be a useless theory, since it's not refutable. But it lends itself to a belief system: by studying the universe, we gain an understanding of whatever created it. This is helpful as a motive: a reason for studying any of this at all, in absence of economic or social incentives.
This seems important. As the centuries tick by, and as we confirm and re-confirm that we are indeed alone and that we do indeed have a mostly-complete model of physics, there will become less and less incentive to analyze the corner cases. It's costly, and takes decades. But at one time, it was costly and took decades to build a cathedral. Yet we accomplished these impressive feats due to a shared belief system.
The reason I brought this up is that we often like to believe there is an advanced alien civilization tucked away in some corner of some galaxy, sending out messages via gravitational waves or neutrinos. But why do humans find this idea so seductive? It's because of an underlying loneliness: we want to believe that we are connected with the universe in some fashion, that our existence has a point, and that there is reason to do anything at all in a universe that will exist long after we've gone, long after our solar system and sun has gone. Because if there were an alien civilization, at least we would not be so alone.
In that context, a solution to Fermi's paradox is simply to believe that our very universe exists due to some higher-order phenomena not knowable within our reality. And by studying the laws of physics, we gain a glimpse into the boundary between our universe and its hypervisor.
No. It's simply that statistically, we can't believe we are the first, nor that we are unique. It would be (statistically) extremely odd if we were, and there is a bias against anthropo-centric theories.
Heck, I'd be happier if we are alone (less risk and more free land), but if we appear to be, that seems odd, and worthy of investigation. No?
EDIT: Why do you claim to speak for all our hopes/dreams/desires? "We need this" or "We want that". Frankly, that's a little collectivist and creepy.
Fermi's paradox does not ask about civilisations like ours. It asks about interstellar travelling or at least interstellar communicating species. We have not achieved this level yet so we are not the 'first' as you say. You might claim that our radio signals should be able to be detected, but they are so weak and have been travelling for such a short period of time that they may as well not exist to an outside observer. There may be millions of our type of civilisation out there presently and throughout history but they would all be undetectable to us and hence our civilisation doesn't play into the paradox.
And you seem to ignore it, but the other part of the paradox is if we can achieve interstellar travel in millions of years, that's like no time at all on a galactic scale. So it would be a major coincidence if we are within 1 million years of the first.
Even so, my point is that human technology tells us nothing about the probility of a civilisation ever developing interstellar communication because we haven't seen it happen yet. We are still at the 0 stage when going from 0 to 1. It doesn't make sense to extrapolate from our position on the technological timeline. It makes more sense to assume tabula rasa that aliens have developed this technology and then explore the implications of that.
Someone did a Bayesian analysis using probability distributions and found that, given what we observe (no aliens), there is a substantial probability we are the first civilization in the universe, or else the only one within galactic distances. They also inferred that whatever makes spacefaring life unlikely is probably in the past, not the future, which seems optimistic if you're worried about AGW or nuclear war.
"The Fermi question is not a paradox: it just looks like one if one is overconfident in how well we know the Drake equation parameters."
"The Fermi observation makes the most uncertain priors move strongly, reinforcing the rare life guess and an early great filter."
They end up with a 40% chance we are alone in the universe and about a 55% chance we are alone in our galaxy.
http://www.jodrellbank.manchester.ac.uk/media/eps/jodrell-ba...
Personally, I think no matter how often matter-energy arrange themselves into life in the universe life remains vanishingly rare. For that reason, life should be as harmonious with itself as possible - diverse and varied but self supporting. The rest of the universe is rarely calm and stable enough for life to exist.
As for why we haven’t found life yet: we are very new to this game. We just in this last decade started being able to resolve properties of exoplanets. I don’t think we have the information to even posit a question like the Fermi paradox with any level of confidence.
0: technically a uniform dim infrared of waste heat
The only stuff I can imagine needing such energy levels would be wormhole gates or Alcubiere drives. Powering the former with a Dyson sphere might make sense but the latter would have to fit on a ship.
The interstellar aliens I find more realistic would be those that just mastered cryo sleep or general AI and built seed ships. We don't really have any way of detecting those, do we?
Even if you've established communication with another civilization, using gravitational waves to carry on chatting seems like an awful waste of resources. The only scenario that seems plausible for using them is some kind of an SOS signal in which case you ensure that it will reach the vastness of the universe and hope that one of the receiving folks would be able to decode it. But then again that would take billion of years.
Could you go into more detail? How do they differ from EM waves?
Though - at that point, why not just send EM waves? They travel the same speed. Maybe gravitational waves could penetrate anything, if you're willing to spend planetary amounts of energy to do it?
https://losc.ligo.org/s/events/GW170104/LOSC_Event_tutorial_...
Note that there's quite a bit of interference from the Earth. (trucks driving about, etc)
[1] https://m.youtube.com/watch?v=iphcyNWFD10&t=376s (6min 16sec into the video)
The fixed channel remains the same, and covers the unstretched distance, so the light, traveling at the same constant speed reaches the end of the unchanged channel within less time than the other channel.
Or invert the same effect for cases where one channel is compressed to a shorter length, since waves oscillate. So both circumstances may be encountered. Some photons will traverse a compressed distance at a fixed speed, other photons will traverse a stretched distance. Meanwhile, the other perpedicular path is neither stretched nor squashed, and the photons in that channel demostrate the difference when compared to the effected channel.
So no matter what happens, the rate of travel is locked at the upper limit of 186,000 miles per second, whether all of space, energy and matter is squashed in a slightly smaller volume, or expanded to fill a slightly larger volume, the relativistic distances do not change, and the rate of passage of time does not change.
Imagine you are in the weightlessness of space, and you measure distances by taking a ruler and placing unconnected beads 10 cms apart.
Now a gravitational wave passes through, what do you see? Nothing. The beads don't move. The intervals you use to measure the distance are stretched in the same way as the space you want to measure in the first place.
So what you can do is, every milisecond or so you lay a new string of beads into empty space. And now when a gravitational wave passes through you'll see that when you lay the string of beads at the moment the gravitational wave passes it doesn't line up with the previous ones.
That you can measure. And by observing the miniscule misalignment of the beads you can see stretching that is much smaller than the 10cm intervals.
So the strings of beads are light rays, and their intervals are the wavelength. The difference is that they don't last, but if there is a light ray in there right as the tube is stretched, it get's stretched along with the tube and you would not see a difference with that, whereas the light that's coming right after it will place new beads/amplitude peaks and actually see the stretched distance.
Is Gravity Quantum?
https://www.scientificamerican.com/article/is-gravity-quantu...
[1] https://journals.aps.org/prd/abstract/10.1103/PhysRevD.90.10...