Airbrush

To paraphrase an earlier quote: "TV and radio signals don't reach very deep space, but at a distance they become so weak that they disappear in the roar of the electromagnetic noise." My question still stands. How far into space does SETI hope to be able to detect a narrow-band signal? Of course, laser detection would catch more distant signals. My other questions: Does SETI send a signal outward, so ETI can know about us? How far out do OUR unintentional radio and TV signals reach into space for ETI's to hear us? Are 100% of all UFOs simply mistake, delusion, or fraud?

Consider that SETI is searching for something that may be only accidentally broadcasted into space. Like the example in the movie "Contact" when we decoded a transmission from space and it turned out to be them bouncing back something from Earth a very early TV broadcast of Hitler giving a speech. Once an ETI achieves the ability to send radio or TV signals into space, they soon realize that they have nothing to gain by broadcasting themselves to outer space. I would like SETI to keep looking just in case. I may have the wrong impression of what they are capable of, and what is possible.

I agree that the basic assumption of SETI is that ETIs would have any reason to broadcast their position in space. What would any ETI have to gain by letting the galaxy know "Here we are! Come and do with us what you will."

To quote from the excellent story you attached: "The belief that an alien civilisation might also be listening to our television and radio signals has also been dashed by the recent discovery that the signals don't, as once thought, reach into deep space: they eventually become so weak that they disappear in the roar of the electromagnetic noise." Then how far into "deep space" do the SETI team hope to listen?

What does your Drake Equation yield? I heard Michio Kaku interviewing a guy working at SETI a couple of weeks ago on his radio program "Explorations". Did anyone catch that? They discussed the likelihood of detecting intelligent signals from nearby stars. The SETI guy, sorry I missed his name, said he didn't know how common intelligent life was, but within the next few decades the SETI search will either find ET(s) or conclude that they are not out there, or at least not transmitting. He was critical of the Rare Earth hypothesis, among other things, explaining how even it Earth had no moon the loose rotational axis would move so slowly that it would hardly pose a threat to early man. He finally and reluctantly gave his current assessment of the Drake Equation and gave his number of ETs, at least as intelligent as we are, as about 10,000 in our galaxy, and probably one within 1,000 light years from us.

That is what I mean granpa, there was too much angular momentum, and low density so very little gravity in the swirling expanding masses of gas and dust, for it to all just fall into the middle and become a SBH. The original eddys in the early big bang became SBHs.

When the universe became transparent, did the expanding mass of atoms have a color or just pure white light, of all wavelengths?

Nice info Widdekind, thanks for sharing. I understood you 100% this time. Let's be on the lookout for an entourage of stars following a medium massive black hole thru our galaxy. How do you think supermassive black holes originally formed? I seems to me they must have formed at the time of the big bang because how does that much matter, Millions or Billions of solar masses, get close enough together to create a SBH? Stars are too disbursed and have too much motion to all fall together like that.

Interesting news, thanks for that. According to wiki one gigaparsec is about 3.262 Billion light-years so one megaparsec is about 3.262 Million light years, or about 60% further from us than the Andromeda galaxy. I grew up using light years. Megaparsecs is not a familiar unit of measure to me and perhaps some others. Space is expanding at the rate of 74 km/sec every megaparsec. If expansion is accelerating, how long until the expansion rate is 75 km/second? Correct me if I am wrong, but using simple math we can calculated how far away this expansion adds up to light speed. That would be at 13.2 Billion light years away where the expansion adds up to light speed (300,000/74 km/sec = 4,054 megaparsecs = 13.216 Billion LY away), which coincidentally is near the horizon of the furthest visible galaxies or quasars. How can we detect the CMB radiation if it is expanding away from us at far beyond light speed? Merged post follows: Consecutive posts mergedTo answer my own question, we can now detect the CMB radiation because it left that region so long ago, when it was much closer to us, so that it had enough time to arrive here.

"...In Einstein Physics, as fast as you travel, as slow the time will be. If that is true, at the speed of the light, the time has stopped...." Time dilation only applies to matter's motion, not light's motion.

If black holes are like a connection with a higher dimension, then maybe that explains supermassive black holes. They exist in our universe because they originated in a parallel higher dimension and leaks over into our universe.

From the little I read about Superstring theory in Astronomy magazine, correct me if I am wrong, I think they said something like the Big Bang was the result of a collision of higher dimensions. I think it was like a couple of bed sheets handing on parallel laundry lines to dry in the sunshine. These flat sheets have only two dimensions of infinite size, and they represent two parallel higher dimensions that are very close together but not touching. The Big Bang was when they came together which might not be at a single point, but could have started from a region, or series of regions, of any size, then spreading outward in all directions? That would explain cosmic inflation?

I watched the video to hear what he said about how small the observable universe could have been early on, and I think he did say smaller than an atom, but I don't remember him ever using the word singularity, just as Martin said. It is hard to imagine 100 Billion galaxies compressed into an area smaller than an atom. That is beyond surreal! So is the word singularity only used for black holes?

George Smoot said that the entire visible universe was once "smaller than an atom". That sounds very singular to me. But that implies a finite universe of only what we can see. If the universe is infinite, then all bets are off about the size of the singularity at the beginning. Does that mean that an infinite universe can orginiated out of a region of indeterminable size, before Planck Time?

"...something 12 light years away moves at the speed of light, etc." I think you mean that something over 13 Billion ly away is expanding away from us at over light speed. Merged post follows: Consecutive posts merged"The 12 lightyears distance would not be growing at the rate c, but would be growing at the rate of 30 million times the speed of light." You have got to be kidding right?

A few months ago I saw a wonderful short video clip, posted here somewhere by Martin, of a nobel winner explaining the structure of the universe to a design school. I think he said the very early universe, at about the Planck Time was smaller than a proton. Did he mean that only the visible universe would have been that small? Or do they no longer give a hint at the size of the singularity of the universe, very, very shortly after the Big Bang?

Certainly 10%C is not a modest speed. Thanks for calculating how long it takes at 1 G. Wow, great story about antigravity for masses moving near light speed. Does that also create a "tractor-beam" like effect that sweeps the path in front of the speeding spacecraft to remove objects that could destroy it? Even a grain of sand impacting at such speed would be disaster. However, I decline traveling thru space that fast. People are not meant for interstellar space travel. Just send probes that can sense everything around so well, the controllers at home will feel like they are THERE.

Oh well I didn't realize that maintaining one G acceleration would get you going so fast so quickly. How long would it take to reach a modest 10%C, which I heard is quite possible in the near future, at a constant one G acceleration? I don't know how to do that math.

Yes, if the starship gets near light speed it will become so massive that it will take more and more energy to maintain a constant one G acceleration. But on trips to the nearest stars, it would be possible to reach maybe a modest 10%C and then turn around and deccelerate the second half of the voyage there. It will take many years anyhow. I would never volunteer for the mission, because it will probably be a one-way trip and space is a dangerous place. They would have to make the trip there a lot of fun to interest anyone qualified. Maybe virtual reality games to keep the space travelors occupied. They will never see Earth again.

If a spaceship from Earth could accelerate at exactly one G on its' way to the nearest stars, that would give the crew exactly the gravity they need to stay healthy over the long term. You can get up to very high speed this way, before you know it. Then half way to the destination, the spacecraft turns around 180 degrees and begins deccelerating at exactly one G until they reach the destination. That will solve the problem of zero gravity during long starship voyages!

Good reference. Right, you are referring to the CMB radiation that is the furthest we can possibly detect, by any available means, because before 13.667 Billion years ago the unverse was still opaque. After that it cooled down and the dark age began that lasted until the first stars and galaxies formed about (what?) one Billion years later? I think I recall the dark age could have ended 200 Million years after the dark age began? I think it is not light at that distance but only a feeble glow near absolute zero. The first light came after the dark age when the first stars ignited. Those stars are about 30 Billion LY away now, and the cosmic background is 50% further at 45 Billion LY away. Merged post follows: Consecutive posts merged We see such distant objects because the light, or temperature reading, left that object or area of space in time for us to see it, and that happens to be limited by the age of the universe and the age of those first stars or areas of gas and dust in space.

We are not 13.7 Billion LY from the origin of the universe. The furthest we can "see" is the CMB (cosmic microwave background) radiation which is now about 45 Billion LY away, or about 50% further from us that the most distant visible galaxy, quasar, or gamma ray burst (GRB), which are now about 30 Billion LY away with a red-shift of about 8 (or 8.2 for that recent GRB). Sorry I don't understand the remainder of your question. Anyone else?

That's a good question Raul. Until Martin or someone else answers, I will take a feeble stab at it. Suppose that light we see now originated from a position 1.4 Billion LY away from us. We are only seeing it now because we never had the capability of seeing that far into space until now. Correct me if I am wrong, but I think if we could go back in time a few Billion years and set up our modern telescopes that can see the object, we would see it back then also, just not as red-shifted as we see it now.

"Where are they?" Assuming that ETI (extraterrestrial intelligence) is wide-spread thoughout our galaxy, maybe SOME of the UFOs are ETs. A civilization that is so advanced that they have found us and can travel here, then they are also so advanced that they know we cannot prove they are here if they are minimally careful to not be caught. They may have advanced sensory capabilities that can alert them when humans are near or they can cause cameras to only take blurred images, and hard evidence never falls into our hands. They could even mount effective dis-information campaigns to keep us chasing shadows, bogus UFOs, while the real ones remain undetectable. If they have been here for thousands of years it was easy for them to evade us up until recently. Now it is becoming more difficult and challenging for them to remain unverified by us.

I propose there is no paradox. The term "Fermi Paradox" was coined at a time scientists assumed there were a lot of ETs in our neighborhood. They all watched Star Trek! Perhaps there are so FEW that they are effectively isolated for a long time to come, maybe indefinitely.