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[wierd]

That would mean the aliens would need to have a reason to communicate with us.  More than likely, for the same reasons we now try to avoid contacting indigenous peoples who have never been contacted by modern civilization here on earth (like undiscovered amazonian tribes, island tribes, et al-- namely, to avoid cultural destruction through the creation of cargo cults, and through disease contamination), it is possible that any ETs consider it taboo to contact us. (Indeed, may already have determined that contacting us is a bad idea, because we dont understand them-- see for instance, people making crop circles-- compare that with the fake runways created by island cargo cults.)

Passive examination of our current communications should be more than sufficient for any nearby vessels to determine that we are just not worth contacting at this time. Without "cellphones", we wont hear them phoning home to their superiors, reporting in on their passive observation based anthropology any time soon.

That is assuming they are even bothering to be watching us at all, for that matter.

[Khan Boyzitbig]

Given how warlike our species is they would likely be observing incase we go beyond our system and cause trouble. Much like if there were 40k Orks on a planet, as long as they stay there, there isn't a problem. But if they get off world someone is going to have a bad day, and its unlikely to be the Orks.

We can wipe out all life on an entire planet if we wanted to. Thats a good enough reason to keep a watchful eye on us.

[Max™]

Setting aside magictech workarounds, reaching this system from another in a reasonable amount of time means you're going to be relativistic for a long time, if they want to stop and look around that means they're gonna need to shine a really fucking bright flashlight at us to drop relative velocity, at high enough fractions of c we might see cosmic rays from dust hitting the front guard of whatever form they use.

[Starver]

Back to the Caveman analogy, those people from New York certainly couldn't get to our cave-village any other way than on the narrow track between the turbulent river and the unclimbable cliff, it's not like they can fly, parachute, abseil, jetboat, etc into our front yard... Deliberately or otherwise.

(Some methods are noisy, but if we don't expect someone to have trekked onto the inaccessible peak/god-mountain that overlooks us then base-jumped down into our secluded grove on a freak gust of wind then we're probably both going to be surprised by the resulting encounter.)

Also, assumes lifespans like ours. With more longevity (and/or any of the pause-and-revive, or scan and duplicate at need, methods, or just a Generational Ship) a casual non-relativistic passage between stars might be easily their type of jaunt.


Not that I think it has happened/is happening, but there are more things in heaven and earth, Horatio, than are dreamt of in your philosophy...

[ChairmanPoo]

Everybody knows advanced spacefaring civilizations communicate via a combination of farting and interpretative dance

[Max™]

Back to the Caveman analogy, those people from New York certainly couldn't get to our cave-village any other way than on the narrow track between the turbulent river and the unclimbable cliff, it's not like they can fly, parachute, abseil, jetboat, etc into our front yard... Deliberately or otherwise.

The relativistic brachistochrone at 95~99% of c is dropping down out of nowhere in a jetpack, we're talking about vastly superior understanding and exploitation of the laws of physics, plus probably needing some sort of fuckery from beyond the standard model like conversion of dark matter into a usable form for thrust, or maybe doing some sort of might-as-well-be-magic nonsense involving quark-gluon plasma analogues for susy-partners or something, because otherwise you hit a "please purchase the full version of physics to continue playing" screen.

Basic "20th century world travelers" from the "we're cavemen" perspective means they can do stuff like fusion torches or valkyrie drives to push up into the 10~25% of c range because that's the point where you start being able to really plan out trips to another star. We can have super clever cavemen figure out possible ways to do this, but we can't do it right now.

That would be "wow, look at that huge canoe, how do you move it?" type of encounters, and noticeable from a good distance.

The "ok, technically that should maybe be possible, but how did you get around ____?" types would be noticeable from much further because there's no such thing as stealth in space, much less at high fractions of c. The engines to achieve that make all of our WMD's look positively adorable by comparison, and best of all: they can serve as a WMD from a whole other star system since the only way to possibly launch some sort of sneak attack is to ramp your ship up as fast as it can go... and then simply leave out the "turn and slow down" portion of the trip.

The gamma-ray shine of the decelerating half was also detectable, but it made no difference. One of the iron rules of relativistic bombardment was that if you could see something approaching at 92 percent of light speed, it was never where you saw it when you saw it, but was practically upon you...
...
In the forests below, lakes caught the first rays of the rising Sun and threw them back into space. Abandoning the two-dimensional sprawl of twentieth-century cities, Sri Lanka Tower, and others like it, had been erected in the world's rain forests and farmlands, leaving the countryside virtually uninhabited. Even in Africa, where more than a hundred city arcologies had risen, nature was beginning to renew itself. It was a good day to be alive, she told herself, taking in the peace of the garden. Then, looking east, she saw it coming -- at least her eyes began to register it -- but her optic nerves did not last long enough to transmit what the eyes had seen.

It was quite small for what it could do -- small enough to fit into an average-sized living room -- but it was moving at 92 percent of light speed when it touched Earth's atmosphere. A spear point of light appeared, so intense that the air below snapped away from it, creating a low-density tunnel through which the object descended. The walls of the tunnel were a plasma boundary layer, six and a half kilometers wide and more than 160 deep -- the flaming spear that Virginia's eyes began to register -- with every square foot of its surface radiating a trillion watts, and still its destructive potential was but fractionally spent.

Thirty-three kilometers above the Indian Ocean, the point began to encounter too much air. It tunneled down only eight kilometers more, then stalled and detonated, less than two-thousandths of a second after crossing the orbits of Earth's nearest artificial satellites.

Virginia was more than three hundred kilometers away when the light burst toward her. Every nerve ending in her body began to record a strange, prickling sensation -- the sheer pressure of photons trying to push her backward. No shadows were cast anywhere in the tower, so bright was the glare. It pierced walls, ceramic beams, notepads, and people -- four hundred thousand people. The maglev terminal connecting Sri Lanka Tower to London and Sydney, the waste treatment centers that sustained the lakes and farms, all the shops, theaters, and apartments liquefied instantly. The structure began to slip and crash like a giant waterfall, but gravity could not yank it down fast enough. The Tower became vapor before it could fall half a meter. At the vanished city's feet, the trees of the forest were no longer able to cast shadows; they had themselves become long shadows of carbonized dust on the ground.

In Kandy and Columbo, where sidewalks steamed, the relativistic onslaught was unfinished. The electromagnetic pulse alone killed every living thing as far away as Bombay and the Maldives. All of India south of the Godavari River became an instant microwave oven. Nearer the epicenter, Demon Rock glowed with a fierce red heat, then fractured down its center, as if to herald the second coming of the tyrant it memorialized. The air blast followed, surging out of the Indian Ocean -- faster than sound -- flattening whatever still stood. As it slashed north through Jaffna and Madurai, the wave front was met and overpowered by shocks rushing out from strikes in central and southern India.

Across the face of the planet, without warning, thousands of flaming swords pierced the sky...

Sleep tight!

[Reelya]

Unless they make a deliberate attempt at communicating in a way we would understand. Such an attempt would likely be from close by (I.E. Inside the Sol System) and very obvious.

Or ... their knowledge is so advanced that they don't really need to dial each other on the phone so much. Consider that we can already detect planets 100s of lightyears away with our shitty tech, then super-advanced aliens would have already mapped out whole solar systems thousands of years before they decided to go there, there might be almost no reason to even have probes, and even then, a tight beam signal back taking eons might not seem like a problem for them. After all if there's something cool somewhere then it will take eons to get there, and you can scan and probe an unlimited number of star systems at once. It's not like you're going to be in too much of a hurry, and once probes arrive and detect anything interesting (that you didn't already know about from your deep-space scanners) then you're going to be getting more interesting places to visit than you can keep up with.

(consider that if you send a probe somewhere 1000 light years away and you can do e.g. 10% light speed on average, then it will take 10000 years for the probe to arrive, and then if the probe finds something, another 10000 years for you to get there. 1000 years to hear back from the probe at light speed then isn't much overhead).

[wierd]

Max:

The author neglected to describe what would have happened after the object's shockwave penetrated the Earth's crust-- which it would have.  It would have still created a crater of impossible size, just from the energy emitted from it detonating in the atmosphere. The vaporized gas pressure alone would have impacted the Earth's surface with so much force, that a kaiser bomb would look quaint. It would shatter the mantle at that location, cause intense pressure waves within the Earth, and rain lavabombs all over the planet.  Just something the size described, travelling at 92% of C, would have more impact than over 100 T-K boundry events. It would end all life on earth, even microbial. It could even blow the Earth apart.

[martinuzz]

What is a kaiser bomb? Google has no info on it, except that there's bacon and sauce on it and it's supposedly delicious, or it has something to do with baseball.

[wierd]

largest bomb ever created by the USSR.
https://en.wikipedia.org/wiki/Tsar_Bomba

Misremembered the name. that's all.  It was the largest nuclear device ever detonated.

[MetalSlimeHunt]

No, you remembered the name right, you were just intersecting with a wierd from an alternate universe.

[Sergarr]

92% of lightspeed only corresponds to about arctanh(0.92)=1.5890269151739728098234708006485 c apparent velocity. Not all that high. Artistic liberties, I guess.

[ChairmanPoo]

truly advanced cultures favor ludicrous speed for space travel

[inteuniso]

truly advanced cultures favor ludicrous speed for space travel

I wonder if we cna use rockets in warp bubbles.

[Telgin]

If warp bubbles can really be made, I think the prevailing fringe theories are that you wouldn't need any kind of conventional propulsion to move.  The warping of spacetime itself would move the ship.  In fact, using a rocket while inside of a warp bubble might cause issues, but I'm hardly versed in the math involved.

That's all if warp bubbles can be made in the first place.  I don't think anyone seriously claims to know how they'd work even if they're possible.  Creating negative mass or energy is kind of a problem in that we don't know such a thing exists and really don't have any reason to believe it does as far as I know.