Presumably any civilisation more advanced than ours would have gone through the radio stage of technological development at some point. The problem is they would have needed to have gone through that stage of development within a very short and specific window for us to have detected it in the time we have had that capability. It makes it incredibly unlikely that we'll ever detect any radio signals of life (unless of course they decided to carry on spamming out radio messages in the hope of them being detected)
That's a really good write up of one of my favourite subjects! My only nitpick is that 0.7 on the Kardashev Scale isn't "nearly I" because it's logarithmic. If I remember correctly, by that same formula we hit 0.5 in something like 1850, and all the advancements of the last 180 years only took us up slightly more to the current figure. An actual Type I civilisation would probably be incomprehensible - let alone a II or III - but I think the author deals with this in the anthill metaphor towards the end. I'm an optimist by nature, so I like to think that the filter is that any given civilisation eventually decides that just uploading themselves into computers and living in an eternal fantasy is better than dealing with real life, and why not.
The trouble with believing aliens have visited earth is the hurdle of interstellar travel. The nearest star to the sun is another one million times further away.. Unless we have something very badly wrong with our fundamental theories of physical laws then we are on our own for the duration.
Not that long ago weren't people saying the same about the possibility of man made flighing machines?
So if not radio then what, gravitational waves? Even they can't travel faster than light and we have detected them. Interstellar travellers no matter how advanced their technology, cannot get round the laws of physics which would mean that their interstellar journeys would take many generations to achieve. Further they would not be capable of getting here before their communications - which travel at the speed of light no matter what technology they are based on. Hence we would have known they were on their way before they got here. We haven't, ergo they don't exist or are so remote that there is zero chance of them coming here. One other thing to consider is OUR radio communications, they have been travelling out from the Earth for over a hundred years and so will have reached a stupendous number of stars within the Milky Way. As yet we have not received any transmissions back from any potential aliens.
Interstellar travel is a whole different ball game to flying. Unless you can travel in excess of the speed of light it's a non starter. And our understanding is that you can't. There's no script here or inevitability. The Universe is full of largely "empty" space and other civilisations so far away we stand no chance of shaking their tentacles.
Any reply would therefore have had to be made after the first 50 years to reach us 50 years later. It narrows down the radius of potential respondents, even if to just a few million/billion.
Imagine getting a message back over the radio waves "we come in peace... and it's a massive grumble for Wednesday"
Looking at conventional physics based on Einsteins theories, you are correct. Many agencies are currently working on many things to sort out the energy problem of catapulting things at great speeds. They are also looking at warp dives, which will bend the space in front of the space ship. There is potential we will get there. Currently with the fastest ship we can make, and if we could power it, it would take 80000 years to get to the next star system.
Read some reports from UFO and UAP experts who believe extra terrestrial craft to be around 50000 years more advanced than what we are right now.
Yes I worked that out after I'd posted it but couldn't be arsed to edit it... According to google there are about 1000 stars within 50 light-years so on the latest estimates, about 1000 earth-sized planets in the habitable zone - which sounds a lot. The probability of life on such a planet being 1 in 10 to the power 12, I think it's fair to say that nobody's there.
What do you call a stupendous number? There are around 60,000 stars within 100 light-years of earth. There's an estimated 100-400 billion stars in the milky way. If we go somewhere in the middle of that estimate at 200,000,000,000 (200 billion) stars, the 60,000 represents 0.00003% of all stars in the galaxy. Or, for every star our radio signals have reached, there are 3,333,333 stars they haven't reached. A 1 to 3.3 million ratio. Within 50 light years of earth, allowing a radio signal to make that journey and return, there are over a thousand stars and we've mapped them. That's a 1 to 200 million ratio. If you look under 1000 rocks, selecting one every 200 million, and don't find a crab under any of those rocks, does the planet earth have any crabs?
What is also possible is that there are "craft" already within the 50 year radius that have travelled from way beyond that radius, randomly searching for their version of extraterrestrial life, who just happened to be within our area and picked up our radio signals. These signals don't necessarily have to be old, ie 50 years, but could be as recent as yesterday or 5 minutes ago, and anyone scanning would hone in on us straight away and with their technology could be with us fairly quickly. You say it's fair to assume there's no-one there but if they were already in the vicinity then anything becomes possible. How they got here is another matter, something we can't understand at the present time.
I admire your optimism, but warp drives and wormholes are at best blue skies thinking and at worst just a convenient plot device for science fiction writers. The same physical laws permeate the entire universe. Also for those still in the UFO camp, I'd urge you to Google the Fermi Paradox.
I’ve no idea. Perhaps our assumptions about how the universe works are wrong? On a related subject but slightly different, someone else asked what Isaac Newton would make of an iPhone if one went back in time to his century. If he managed to switch it on most of it would not work (no WiFi) and if he took it apart he wouldn’t understand it. That’s 300 years or so ahead of his time and we’re talking about civilisations with technology potentially tens of thousands of years ahead of us?