Try wrapping your brain around this: Cosmologists detected 2 supermassive black holes at the far side of the universe and they were orbiting each other. One was 29 solar masses, and the other was 36 solar masses. HUGE! They were very close and about to merge and as they grew closer they were orbiting each other at 6000 RPM!!!!!! ONE HUNDRED ORBITS PER SECOND. They subsequently merged into one.
Well, it turns out that outer space is a near perfect vacuum. We sent out voyager I and II. There isn't any projection that they will EVER come closer than a few light years from another star.
Voyger I and II are not seen as likely to approach stars inside the Milky Way galaxy. And, there would have to be some sort of major interaction for either object to get tossed out of our galaxy. And, if that happened, we'd be into the billion year range.
https://www.space.com/22783-voyager-1-interstellar-space-star-flyby.html Now that NASA's Voyager 1 probe has left the solar system, its next big spaceflight milestone comes with the flyby of another star — in 40,000 years. Voyager 1 entered interstellar space in August 2012, nearly 35 years after blasting off, scientists announced Thursday (Sept. 12). As it leaves our solar system behind, the robotic spacecraft is streaking toward an encounter with a star called AC +79 3888, which lies 17.6 light-years from Earth. "Voyager's on its way to a close approach with it in about 40,000 years," Voyager project manager Suzanne Dodd, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., told reporters Thursday. "It's going to come within 1.7 light-years of this star — and it'll swing by it, and it will continue to orbit around the center of our Milky Way galaxy."
That certainly is a good point. But, I'm still happy with what I said. I would plea that I was still within reasonable limits as at its closest to that star, Voyager will still be hugely far from that star - more than 1/3 the distance between the nearest star and our sun. At its closest, that is 10 trillion miles - 100,000 times as far away as our sun. Voyager would still see that star as a tiny dot. If something traveled that "close" to Earth I would rightly be questioned about calling that an "approach" at all. The new suspected planet is hugely far from our sun, but only a miniscule percent of the distance of the Voyager approach. 10 trillion miles is a tough commute, but you're right that astronomers would see that as "flyby", since even the inside of our galaxy is such a great vacuum.
I wasn't questioning your comments...only providing some information. Seems to me better understanding how light travels might be key to human space travel. Or perhaps humans can never travel at speeds much greater than 50k-100K mph so it must be something else traveling 'in' a light wave. Have we pointed the strongest Earth lasers towards goldilocks planets? Or are we just looking for signals from others?
There is a group that is broadcasting toward specific planets. It's not part of SETI. I forget their name. They point out that our earthly activity would be impossible to detect from one of these planets were those beings limited to the technology we have today. Our communications broadcasts of today would be far to faint to detect. So, this group plans to directly aim electromagnetic signals at specific locations. I don't believe they use lasers, though. As for actual travel through space, we know how to make stuff go many times faster than 100k mph. However, distances are large enough that it doesn't really matter. If we were to travel at ten million miles per hour, the nearest exoplanet (a little over 4 light years away) could be reached in roughly 2.5 million years - many times longer than modern humans have walked on earth. The next nearest exoplanet in the habitable zone is 11 light years away.
It seems it would be very difficult to match the technologies of civilizations vast distances apart over millions/billions of years in order for either to recognize the other. Seems that with SETI we should search for something more organic outside of technology...by-products of intelligent beings. But, light seems to be one constant everywhere in the Universe so maybe searching for light, or emitting light, is the way to go? It's these vast distances that seem to dictate that without discovery of new physics that travel is relegated to a couple of astronomical units and can we call it communication if it takes 22 years to say 'hello' and have someone else say 'hello' back to us?
I agree with what you have hear, at least generally. I'm not opposed to SETI, as it isn't a big expenditure and could possibly find evidence that we aren't alone. That would be a big deal even if it were far enough away to make communication a ridiculous idea. Plus, it seems like every time we find a new way to "look" we find things we didn't expect to find.
I think SETI is great and required in order to better understand stuff. Good that lots of private sector dollars are being used...
I like the private dollars, too. And, it goes beyond the big projects stuff. A lot of asteroids, etc., are found by amateurs who have to know their stuff if they are to actually find such objects.
Chances are that by the time anyone hears us we will be gone and if they reply we will be hearing from long dead aliens. Relativity my dear Watson.
Yes the asteroid and planet hunters are typically amateur astronomers. Plus bigger support from people like Paul Allen. Can't remember several years ago maybe The Planetary Society and their SETI program was using personal computing power?
Except if there are chances of ET's within 20-50 light years or so of Earth. Perhaps unless a planet is completely destroyed, intelligent life can appear, disappear, and reappear many times over when talking about billions of years? The vast distances, although daunting, also can mean more opportunities for ET's. Does anyone know how far our typical radio signals will travel with adequate power to be detected by ET's?
I think that's all true. Good stuff. A major change to some of that is closing in. There are plans for a satellite system oriented to finding and tracking asteroids that is likely to leave amatures unable to compete in finding any previously unknown object inside our entire solar system. People are getting interested in protecting earth. And, that requires early identification of possible threats. Plus the science objectives, of course.
I hope the satellite system you talk about is always looking up instead of the military using it to look down for airborne weapon launches. Depending on the size and threat of an asteroid, even if we can spot them then what do we do?
From what I've heard it seems like we would need a good number of years to design a way of deflecting an object. Apparently they are different enough in trajectory, speed, composition that it's not like one approach works for all. The idea is that these objects usually make a number of passes before they would actually hit earth. So, it's reasonable to do a good job of looking in order to give us the years we need to build a solution and get it launched. One problem is that they are really hard to spot - they tend to be cold and not very reflective. There is a proposal that the best way to find these would be to have a satellite traveling inside earth's orbit at earth's speed - that is, staying between earth and the sun. Then, it can look toward earth away from the sun. Objects would then be easier to see, because they would be warmer than the background of space. It's always hard to invest dollars when the odds are against needing the protection within one's lifetime. But ...
Amen. I would suggest that money spent on detecting space objects is essentially a type of insurance. And, today we don't want to cover health care, which is much more likely to save those alive today than is space object insurance. Still, we might get a satellite that is more capable of finding dangerous objects simply because knowing what's floating around is interesting to science.
Reminds me of a sci fi story about the first interstellar mission. It had all the usual stuff about suspended animation so the crew would survive the decades long mission, blah, blah, blah. When the ship arrived at Alpha Centuri it found a bustling city of humans who commuted to and from the Earth in a faster-than-light drive invented a few years after the mission took off.
Lol. Good basis for a story - a tiny bit like time travel, ending up in the future of earth people, in a way! I have read such possibilities from guys at NASA. Not about lightspeed. But, the distances are so stupendous that one doesn't have to go that much faster in order to catch some already-launched ship that used the best we have today - or even could have given current ideas.
Last I read the NASA budget was around $18 billion, while numb-nuts demands $30 billion for a wall that serves almost no purpose. NASA's budget could be doubled with the snap of someone's fingers yet our legislative and executive branches are clueless and uninterested...half of them think science is fake news. There should be a multinational effort to put in place a space object early detection system. You mentioned having some 'years' after discovery to figure out how to combat an object headed towards Earth but we won't have those 'years' without early detection. And this type of program creates jobs and can benefit military research. There is no downside...
Some satellite news ... https://www.space.com/39504-nasa-gold-back-on-track-launch-anomaly.html NASA GOLD satellite launches sort of successfully. It's a mission to study the upper atmosphere, launched on a European rocket. That rocket had problems, with a communication failure after launch. The satellite went up on auto-pilot, so to speak, to the altitude where it deployed and waited for a second boost command that never came. Communications were reestablished, but by that time, the boost window had passed. A new boost window will arrive in a month, so they'll do it then. No word on why the rocket failed like that. https://skyriddles.wordpress.com/2018/01/21/nasas-long-dead-image-satellite-is-alive/ NASA's IMAGE satellite, which went non-communicative in 2005, was recently found to be phoning home by an amateur satellite tracker. NASA agrees that it's IMAGE,and is trying to re-establish good comms.
Weird! I had no idea stuff like waiting for another boost window was even possible. And, how did they manage to not hear their own satellite?
