Lets Talk About Things Science Cannot Explain

As I thought! I do the ph. charger trick too, there are so many discarded pre-90s phones it's ridiculous.
How many magnets does one guy need anyway? I stopped after three bags full. Neodymbulbium magnets can be finger pinchers, be careful when dismembering hardrives. I wonder about the effect of 3,075 magnets under the bed at night.
 
Why can't science come up with The Theory of Everything ?
 
Mostly I yam glommed neodymiums from old tower HDs, so they are plenty strong. Hard to separate from each other, a real danger to guitarists or other finger workers. SnAp!! I really do have hundreds and hundreds of them... but still can't attract much worthwhile.
Obviously, the best use is to attach a few dozen to a hook and troll the lake or river, hoping for metal treasure.
 
Why we have found no evidence of intelligent lie in the universe . No Radio signals.
 
Our omnidirectional radio signals that have been broadcast for the last hundred years odd are maybe just about detectable a few light days out from the solar system after that the inverse square law makes them virtually undetectable. Also, based on our own behaviour, omnidirectional broadcasting is something a technological civilisation will only do for a very short span of time. It won't be long before all our radio transmissions are much more tightly focused and less wasteful. Only a very tightly focused beam stands any chance of being detected at any greater distances (think military grade pulsed radar) and by it's nature any such alien signal would have to be pointed directly at us and for long enough for us to happen to look in the right direction to detect it. Why would they do that? Seti is, sadly, and in my view, a complete waste of time. Even if they are out there we're never going to pick up their radio signals.
 
Vertigo said:
Only a very tightly focused beam stands any chance of being detected at any greater distances (think military grade pulsed radar) and by it's nature any such alien signal would have to be pointed directly at us and for long enough for us to happen to look in the right direction to detect it. Why would they do that? Seti is, sadly, and in my view, a complete waste of time.
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Even then the range is likely less than 100 LY, which is just the end of the street and probably not much more than half a dozen neighbours.

SETI via radio is pointless.
SETI via spectroscopic analysis using space telescopes is feasible.
 
Vertigo said:
Our omnidirectional radio signals that have been broadcast for the last hundred years odd are maybe just about detectable a few light days out from the solar system after that the inverse square law makes them virtually undetectable.
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@Vertigo I don't doubt the science behind this statement, but how much of it could be compensated for with very sensitive receivers? I'm thinking the Pluto probe now, of course it is a very directional beam, but it is also a very low powered beam relying on very, very, good receivers. How much of an increase do we get the better equipment. --- I know that this is just speculation, but you or someone else might have a somewhat educated guess about this.
 
The big difference is between a coherent* radio beam and an omnidirectional beam. The inverse square law is purely down to the spread of an omnidirectional source (like the sun) where the light/radio waves are being spread over an ever larger sphere as they move farther away from the source. Therefore the original power is being spread ever thinner. Hence the inverse square law. There's no real way to get around that unless your omnidirectional source is incredibly powerful like a star and even the less strong examples of stars become difficult to detect over very long distances. Very little power is lost to attenuation as there is so little stuff in space to block the signal, though of course there is some, so over very long distances some signal will also be lost to dust in space (very hard to detect stars in or behind significant dust clouds). The problem is that combine the inverse square law with that little bit of attenuation and then add in trying to separate such a tiny signal from the signal coming from the star whose system it originates in and frankly no matter how sensitive your receiver the chances of detecting anything are rapidly falling to impossible.

On the other hand take even a low power coherent signal in a tight beam (and over interstellar distances that beam needs to be incredibly tight) and it will hardly diminish at all. if the Pluto Horizon probe signal is sufficiently tight then the signal coming from it today will be hardly less than when it was say around the orbit of the moon so long as it is pointing in exactly the right place which of course it is. However we can't make radio beams all that tight so over interstellar distances even they are likely to disperse too much to be detectable. As I said earlier I believe it is thought that military strength radar might be detectable at some of our nearer starts but it must be pointed exactly at the target star. And then hope that some alien living at the target star just happens to be looking at you at just the right time to see it.

So you first have to decide on what star you want to send a signal to then point an incredibly tight, powerful (and probably very expensive) transmitter at that star and start transmitting and keep transmitting for oh say a century or two in the hope that they happen to look our way. Consider SETI; I don't know how many stars it scans every night but even if it's hundreds there are billions out there and it doesn't/can't watch them for a decade it only watches them briefly and then moves on to another one. So really the chances of detecting a signal are, sadly (very sadly), vanishingly small.

As Ray says the best real possibility of detecting life is to detect the signs of that life in exo-planet atmospheres. Note that what you are doing there is using the incredibly powerful transmission of a star and then applying spectroscopy to the light from that star that is passing through or reflecting from the planet's atmosphere. Then just suppose you have detected chemicals indicative of a technological civilisation and so decide to transmit a signal at them. First that signal must be tight enough, then you have to wait however many years for the signal to reach them and then hope that they're looking our way... :(

Oops sorry for the excessively long post. It is an area I am fascinated in (despite how pessimistic I may seem about our chances....).

This page here - How Far Have Our Radio Signals Traveled From Earth? - gives a fairly nice simple explanation, though it suggests detection is possible out to few light years which from what I've read elsewhere is extremely optimistic.

* I think coherent is the right word here (I'm sure Ray will be able to confirm/correct). But it means as tightly parallel as possible so no spread at all. Lasers and radars are good examples.
 
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Parson said:
but how much of it could be compensated for with very sensitive receivers?
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We have been at the physical receiver limit for years. Even a room temperature receiver is pretty marvellous, about 0.3dB NF. Professional gear can be liquid nitrogen cooled. You can now only have bigger dishes and more off them. My rough figures are based on both ends pointing at each other with crazy big arrays of crazy big dishes.
The limit is Cosmic background noise. I can have good enough gear here that out performs that at room temperature!

The Pluto probe is really very close, very low data rate and VERY big dishes this end. The New Horizons or ANY probe / satellite has to point its dish exactly at us or we can't communicate at all.

Even a big dish still has a an inverse square law, it's just collecting more signal (aperture), gain. So with a 46dB dish gain my signal is that much stronger, but 10 times distance is still 100 times weaker (20dB).

Pretty much even if both ends of 100 light years away planet pointed giant dishes, it's still dubious. Maybe at 10 LY.
Round trip time is Light Years distance x2 as years.

Both beamed and omni radio is coherent, like a laser is. Gain goes up with cube of frequency for a dish, so optical laser and dish has more range than radio for same dish size and power. That needs to be in space as atmosphere is a problem. Also inherently easier to do 1000x power of radio than optical. SETI mostly just listens, unless someone is less than 10 to 100LY AND pointing at us, we can hear them.

With Spectroscopic Analysis the "transmitter" is an entire star! Any molecules in the atmosphere of planet cause dips in the star's spectrum as the planet transits the star. We KNOW this works and HAVE used to to discover what gases are in atmosphere of distant planets. The next Space Telescope (James Web?) will be far better than ground based or Hubble doing this.
A Star is billions of times more powerful than any planetary based laser or radio transmitter!

Vertigo said:
So really the chances of detecting a signal are, sadly (very sadly), vanishingly small.
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Zero I would say!

Vertigo said:
Then just suppose you have detected chemicals indicative of a technological civilisation and so decide to transmit a signal at them.
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I think we can't transmit anything by radio or laser.
1) They'd have to be looking at us
2) You'd need about a hundredth of the power of the sun for any likely destination, and they need to be looking at us.
3) It's not possible with any known practical or theoretical technology to reach more than maybe 5LY to 20LY, at a very slow data rate, AND they would need to be pointing a massive array of dishes straight at us!
Oddly sending a physical probe is possible. It would take a very very long time. But is more likely to work!
 
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Omnidirectional vs "beam"
Coherent isn't the issue, that's easy for Radio compared to Light.

Omni is a sphere expanding. Twice the distance and you have a quarter of the signal hitting the same destination area, because area is proportional to diameter of area squared.

A "beam" is actually a cone "cut" out of a sphere expanding. So the narrower it is the more gain. The bigger the dish, the narrower the beam. Even a laser beam is a collection of cones the width of the laser exit. It's just a much narrower cone than a big dish gives.
If the distance is doubled, then the diameter of the patch of laser or radio illuminating the destination is doubled. Thus area is times four, so the SAME area of destination (the receiver or transmitter) gets one quarter signal. That's where the inverse square law comes from. It's not something mysterious to do with light, radio, xrays, heat or even gravity. Simple geometry.

There are no parallel beams. All transmission or reception of ANY kind of signal is simply a geometrical 3D fractional cone (or a collection of cones) of an expanding sphere.

Virtual Dish for Resolution made from many dishes far apart.
If you have 100 dishes for radio (or in theory light), that's about the same signal as one dish ten times diameter. They have to be carefully pointed. If they are moved far apart you get no extra signal AT ALL. However you do get more resolution as if you had a very much larger dish. This means if the signal (light or radio) is above the background noise (like a star), you can perhaps separate out the signal of two separate stars tens of thousands of light years away or even in another galaxy. It's no help for artificial signals as they are billions of billions of times weaker than a star!
 
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Nice explanation for us lay types Ray. Meanwhile... I just found a cleaning bot - a 'Roomba' vacuum, outside, and have it on the table here wondering what is what. There's a sensor, and a remote, motors, what not... This mangled bot is worth 17cents/lb.
 
Okay, I'll smash it up and report back. *
mmm... nice white circuit board... a zillion screws to take out... looks like the usual components, not worth the time. The little sensor box and the remote... nah it's junk.
 
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Hey,I do this while at the coffeeshop, and some guy just grabbed up a nice power amp and two wooden speaker enclosures. There's about a hundred forks and spoons... unused, new... all from a dollarstore, who dumps stuff in the dumpster even tho there's a donor box a few yards away. So we shift some of it over, good deed for the day.
 
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