Alien Telescopes, Remote Sensors, and Billion Year Old Civs

[ZenGalacticore]

Pardon the interruption of a very interesting thread.
Would there be a possibility of a modified gravity lens?If light can be bent quite successfully around a planetary and solar source,surely it's not beyond an advanced civilisation to utilise this phenomenon?

Thank you for your interest. You are not interrupting. (And your manners... I'm not used to such politeness, upbringing, and culture around here! :| )

I agree that alien intelligences--and we-- could use the bending of light through mass and gravity; gravity waves; bending and warping of spacetime; possible manipulation of unseen dimensions; and who-knows-what-else to communicate (and travel) across the light-years.

I guess we shall see as the years and the progress unfold...

Welcome to SDC, Mr. Grunt. (futtock)

 

[ZenGalacticore]

At any rate... Folks, I was waiting on data from the Kepler and other remote sensing telescopes to continue this thread.

So, until the data pours in --which I have confidence it will-- I will wait til then to post further here.

Keep the faith!

We will continue to discover the unknown; and I'm fairly positive that distant intelligences are hoping for the same!

(It's all about "universal" funding. )

 

[Gruntfuttock]

Pardon the interruption of a very interesting thread.
Would there be a possibility of a modified gravity lens?If light can be bent quite successfully around a planetary and solar source,surely it's not beyond an advanced civilisation to utilise this phenomenon?

Thank you for your interest. You are not interrupting. (And your manners... I'm not used to such politeness, upbringing, and culture around here! :| )

I agree that alien intelligences--and we-- could use the bending of light through mass and gravity; gravity waves; bending and warping of spacetime; possible manipulation of unseen dimensions; and who-knows-what-else to communicate (and travel) across the light-years.

I guess we shall see as the years and the progress unfold...

Welcome to SDC, Mr. Grunt. (futtock)

Thank you young sir.Glad to be here,well at my age I'm glad to be anywhere.

This whole telescope thing.Maybe even if you could build a refractor with sufficient light gathering power and the massive focal length needed what would you see?Since you're viewing from above,and we've all see satellite images,the only impression one might get of the human species would be a hairy ball moving around(or a shiny round one!).And it would only be when that subject is stretched out in sunbathing mode would you glean the perambulatory(not to mention the reproductive ) methods.In short,not much perspective from above.You could follow a subject to the horizon but still would get a squat,truncated view - plus you've got all the atmospheric problems which might foul up the images like thermal currents and so forth.Which is why we position telescopes on mountain tops and in orbit.

How would you feel anyway to being observed thus?Indignant?I think it's bad enough with all these damn cameras everywhere.Perhaps we should all carry placards with "take a photograph - it'll last longer" as a riposte.

:lol:

 

[RikF]

In short,not much perspective from above.You could follow a subject to the horizon but still would get a squat,truncated view

:lol:

A civilization that has the capability to observe such detail from that great distance would also have the ability to one way or the other measure depth and somehow resolve the problems with looking from above, i think. In addition to that they would be able to pick up radio and TV broadcasts. A fascinating prospect.

 

[qwain]

It seems to me that a sufficiently advanced technology would find a way of using naturally occurring phenomena in the universe to communicate across the great distances of the universe. Take gamma radiation emitted by neutron stars. Although gamma rays are too energetic to be modulated in the conventional sense, sending heavy objects in orbit around a neutron star to interrupt the length of the constant gamma burst at regular intervals to create binary messages that are readable by other sufficiently advanced technologies is possible (though practical is another thing), and the interrupted burst are capable of being detected across most of the known universe, even by technologies such as ours that may not be looking for modulated gamma rays.
Altering sunspot activity on stars enough to change their appearance to other systems, if it is possible to cool a specific area of a star's surface, would be another way for alien civilizations to communicate, using telescopes to interpret the messages being sent, and conversely cooling areas of their own stars in reply.
I won't go into the nature of such beings, since they'd have to be either very long lived or immortal for such a communication array to be practical, but it is plausible that by the time a civilization is capable of spanning the distances between stars the wavelengths we believe would be useful in communicating between star systems would have been discarded for something more practical to true spacefarers that would not be obvious to us earthbound aspirants.
Qwain

 

[kk434]

Yeah, this speed of light limit is WERY annoying, even to potential aliens so they will with a huge TPF like telescope watch our planet(with the mandatory 100+ year delay) and not even think about sending a craft and wait for 100 years for results. When we finnaly build a telescope like TPF it will be possible to determine if a exo planet has life, and i time we will watch the aliens as well. When NASA Origins program was online they calculated what size of telescope you need to se an exo planet not as a dot but as a couple of pixels, they found out that about 40 Webb telescopes working as an interferometer with a 1.000.000 km baseline can do it.

 

[eburacum45]

It might be an idea to look at the physical constraints on remote sensing. Even with the Hubble telescope we can't see the Apollo landers on the Moon, a quarter of a million miles away. The nearest stars are two hundred and fifty trillion miles away, a hundred million times as far away as the Moon. If we had a telescope with a hundred million times the resolution of the Hubble we still couldn't see the Apollo lander from Alpha Centauri, let alone a single human being.

So remote observation of a civilisation from another star system is certainly not a trivial problem.

 

[ZenGalacticore]

It might be an idea to look at the physical constraints on remote sensing. Even with the Hubble telescope we can't see the Apollo landers on the Moon, a quarter of a million miles away.

I don't know, have they ever tried pointing Hubble at the moonlanding sites? It took some great, crystal clear and detailed pics of Mars at its closest approach of around 35 million miles. (And a great image of Jupiter as well, 500 million miles away.) And we've only been building telescopes for a few hundred years.

The nearest stars are two hundred and fifty trillion miles away, a hundred million times as far away as the Moon.

While the nearest stars are millions of times further away than the Moon, there are plenty of star sytems closer than 250 trillion miles. Alpha Centauri A and B are roughly about 24 trillion miles distant. Tau Ceti, a solitary sun-like, G-8 main sequence star, is about 60 trillion miles away. And there are scores more within a 200 trillion mile radius.

At any rate, our telescoping technology is exponentiating. The binocular telescope that just went into operation in Arizona will be able to see better than the Hubble, they're saying. Who knows what we'll be able to see, and with what resolution, a hundred years from now.

If we had a telescope with a hundred million times the resolution of the Hubble we still couldn't see the Apollo lander from Alpha Centauri, let alone a single human being.

A hundred million times? I'd have to ask M.Wayne about that, but I think with that kind of x power we would be able to see the lander on the Moon.

So remote observation of a civilisation from another star system is certainly not a trivial problem.

Never said it was! But it might be easy for a technical civilization a million years older than ours.

 

[eburacum45]

While the nearest stars are millions of times further away than the Moon, there are plenty of star sytems closer than 250 trillion miles.

Ah yes. I was out by a factor of ten. Apologies for that! So the hypothetical Alpha Centaurians only need telescopes 10 million times as powerful to see the Moon with the same resolution as Hubble. That is perhaps a little more achievable.

I don't know, have they ever tried pointing Hubble at the moonlanding sites?

Yes. Here's the Apollo 17 site as seen by Hubble:
http://www.lpod.org/wp-content/uploads/ ... Hubble.jpg
A nice image but it does not have the resolution power to see the lander itself.

If we had a telescope 30,000 km across, this is the sort of resolution we'd get at the distance of Alpha Centauri. I'd be very happy to see such an image, but it wouldn't show individual Alpha Centaurians- or even an Alpha Centauri greyhound bus.

To get such a large telescope, you'd need to link several space telescopes together in an optical interferometry array-
http://en.wikipedia.org/wiki/Astronomic ... rferometry
this might be possible, one day.

 

[ZenGalacticore]

http://www.lpod.org/wp-content/uploads/ ... Hubble.jpg[/url]
A nice image but it does not have the resolution power to see the lander itself.

Interesting, yes, but not a very impressive image. The images of Mars actually were crisper than those. I wonder, is the Moon too close for Hubble to adjust to without a blur?

If we had a telescope 30,000 km across, this is the sort of resolution we'd get at the distance of Alpha Centauri. I'd be very happy to see such an image, but it wouldn't show individual Alpha Centaurians- or even an Alpha Centauri greyhound bus.

It's common, when thinking about future technology, for us to think in a linear fashion. Perhaps more refined substances for reflecting mirrors and optical telescopes will be developed, negating the need for ever larger instruments.

To get such a large telescope, you'd need to link several space telescopes together in an optical interferometry array-
http://en.wikipedia.org/wiki/Astronomic ... rferometry
this might be possible, one day.

Please read the whole thread, I'm sure you will find it interesting. I believe I mentioned multi-arrayed "bug eyed" optical telescopes and interferometers earlier. I wonder what a multi-arrayed instrument the size of Ceres, or even Pluto, say, might be able to gather.

Unless one believes that man is approaching our technological asymptotic limit (and there's no reason I can see why anyone should believe that we are), there's no reason not to believe that a technical civ a million years more advanced than us would have unimaginable remote sensing and detection, as well as fine detailed, imaging capability.

Don't forget the U.S. Patent Officer who said in 1899: "Everything that can be invented, has been invented." In just two or so years after saying that, he was forced to eat his words, mightily. (The airplane and radio come to mind!)

What would Galileo, just a few hundred years ago, thought about Hubble, the LBT, or the Kepler Telescope? What would Marconi, just 110 years ago, thought about today's radio telescopes?

 

[eburacum45]

Interesting, yes, but not a very impressive image. The images of Mars actually were crisper than those. I wonder, is the Moon too close for Hubble to adjust to without a blur?

No, it is a question of physics. The resolution of a telescope is a physical law, as impossible to break as the speed of light.

It's common, when thinking about future technology, for us to think in a linear fashion. Perhaps more refined substances for reflecting mirrors and optical telescopes will be developed, negating the need for ever larger instruments.

Refined substances wouldn't help; the equations for resolution are only concerned with aperture, wavelength and distance. See
http://en.wikipedia.org/wiki/Angular_resolution

To increase the resolution without getting any closer you can either increase the aperture (which can be done using optical interferometry) or decrease the wavelength. UV telescopes should be able to resolve more detail than visible light telescopes-
http://en.wikipedia.org/wiki/Ultraviolet_astronomy
but the atmosphere of an Earth-like planet would block UV somewhat, making it difficult to see the Alpha Centaurans clearly from our point of view.

 

[ZenGalacticore]

If more refined substances cannot help, then why aren't we just using the same grinded lenses from the 16th century?

 

[SteveCNC]

I have to agree that with technology advancing as it is now the possibility of seeing our planet and possibly our satelite system's could be possible . I'm amazed at our abilities now vs just 30 years ago to see other planets orbiting other stars . In the future the ability to disern coherent light from non plus extremely sensitive sensors could potentially see things we can only imagine today . So to believe that an alien life could possess that ability already is not beyond the realm of possibility IMO . I think light has limitations as far as seeing us down on the planet but they certainly could detect the gasses in our atmosphere along with temperatures and size etc from long range . And if their really good they could see us when we are above the atmosphere from long range if the angles are right .

As to the time issue , due to the speed of light they cannot see into the future so they would be looking at an old earth , but look on the bright side , if they are say 2000 light years away , in 2000 years they will know we have achieved space flight assuming they haven't seen one of the voyagers yet

 

[eburacum45]

The resolution formulae assume perfect materials, and any materials we do use diminish the results to a greater or lesser extent.

On the subject of optical interferometry- to get good results from an array of space telescopes, the various elements would have to be very precisely aligned. This alignment is probably the part of the technique which is going to be the most difficult to achieve - maybe there are ways of getting around this using information technology.

Rather than trying for better and better optical materials, future telescopes will combine the light, and the information, from widely separated instruments in ingenious ways.

 

[MeteorWayne]

If more refined substances cannot help, then why aren't we just using the same grinded lenses from the 16th century?

The main reason is that newer glasses have less change in size with temperature change. Also the honeycomb design makes the mirror lighter (so less gravitational distortion) and less thermal mass (also faster to cool and reach proper shape).
They reach true focus sooner.

And now with adaptive optics, the shape of the mirror is continuously refined (at the scale of milliseconds) so many small mirrors are combined to make a larger continuous primary reflector. Earlier technology warped a single primary mirror, but with less mass in each second, leading edge designes can respond faster. No inteferometry is required since for all intents and purposes it is one mirror.

 

[ZenGalacticore]

So, has technological advancement in the materials we use to make lenses and reflecting mirrors had any impact on our ability to see farther into space or not?

I don't see that it has not. Our ever advancing imaging capabilities are tied in to many factors, not just how we align the mirrors or in what type of array we position them. And of course, remote imaging and detection isn't just about the visible light spectrum. It's about ALL the spectra.

 

[eburacum45]

Adaptive optics is realy an information-based technology, rather than a material based technology. Materials are now about as good as they can possibly get- if we want more resolution we'll have to increase aperture and use adaptive optics or get above the atmosphere.

 

[Astro_Robert]

Its not just lenses and mirrors, but also sensor materials.

Think of the Hubble Space Telescope. The mirror is the same, it has not changed since launch. What has changed are the cameras. What makes the cameras better is that the newer ones are more sensitive to the photons that the optics gather, and thus WFPC2 could take pictures much more quickly than camera1. Some of the cameras may also take advantage of a wider portion of the spectrum that the Hubble mirror focuses than older cameras did.

There are similar stories to tell with telescopes/cameras for all areas of the spectrum, including x-ray and gamma-ray telescioes. Our materials technology does help our detection methods for a given size due to sensitivity, but resolution will still require larger instruments, presumably though interferometry.

 

[ZenGalacticore]

Adaptive optics is realy an information-based technology, rather than a material based technology.

I won't argue with you that adaptive optics is an information-based technology or is not a part of it. (But without the hardware, our computers and software would be unable to adjust for squat.) And the materials we use to collect light are also a part of it. A big part of it, especially in visual-light, optical astronomy.

Materials are now about as good as they can possibly get-

Famous last words.

I've read some of your posts, Eburacum, and you seem to have a handle on some technical aspects of astronomy. But, you apparently have no historical perspective on the technological progression of the last few centuries, or even the last 100 years. We have no reason to believe-in fact, every reason to NOT believe-- that "materials are now about as good as they can possibly get."

You may or may not be an optical technical specialist, but it is evident to me that you lack imagination and foresight, as well as historical perspective. We've only had telescopes for 400 years, and according to you, in the year 2010, we've reached the pinnacle of materials processing and purity.

 

[SteveCNC]

I may well turn out that better crystals can be grown in a weightless environment which could lead to better optics , one can never tell what road the future will take till it's already made the choice . who knows maybe far into the future it will be possible to make a better telescope all done in micro-gravity .

 

[eburacum45]

We have no reason to believe-in fact, every reason to NOT believe-- that "materials are now about as good as they can possibly get."

You may or may not be an optical technical specialist, but it is evident to me that you lack imagination and foresight, as well as historical perspective. We've only had telescopes for 400 years, and according to you, in the year 2010, we've reached the pinnacle of materials processing and purity.

Well, how far from perfect are the materials we use now, and what improvement would the use of hypothetical perfect materials actually bring? If the materials we now use are (say) 95% as good as they can possibly be (probably an underestimate) then using hypothetical perfect materials would only bring a 5% increase in resolution. However doubling the aperture, shorter wavelengths, the use of adaptive optics (an information-based technique) or space-based telescopes would bring much more benefits than simply improving materials.

 

[eburacum45]

Its not just lenses and mirrors, but also sensor materials.

Oh yes, I forgot that. You are right. Sensors can be improved considerably; if ZenGalacticore is talking about improved sensors then he is quite right.

 

[ahook12]

Why are we limiting ourselves to glass telescope technology. We know that gravity can bend and focus light on a very large scale. In the distant future I can foresee telescopes using gravity or some other as yet unknown force field to focus light on a scale that would be unimaginable today. Think of a telescope with a primary mirror of 100,000,000,000 meter diameter. What would we be able to see then?

Allen