There are several possibilities that affect the prospect of interstellar travel beyond the lack of technology to do it. It's possible and even likely that while planets are common habitable planets are extremely rare. The collision that gave us the moon rearranged our planets geology. We have a big dynamic core with a thin active crust. This gives us a nice magnetic bubble that shields us from cosmic radiation. We really can't five very long anywhere else without digging a hole in the ground to hide from the radiation. That's the main reason we can't move to the moon or Mars or anywhere else in this system. The atmosphere we want needs life itself to turn CO2 into O2. So a habitable planet will have to already be inhabited by at least the bluegreen algae we have here. The odds of that happening very slim. It's highly unlikely we will find this in more than a very few solar systems. At the other end of the pessimism spectrum, any habitable planet will already be inhabited by beings intelligent but unwilling to share with us. We may be looking for a quiet suburb but only finding other versions of Detroit DT From: Richard Tenney via Utah-Astronomy <utah-astronomy@mailman.xmission.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Monday, February 23, 2015 11:31 AM Subject: Re: [Utah-astronomy] To call or not to call. That is the question. I went and finally saw interstellar this weekend, since we're on the topic. Curious what others thought. I thought it had promise starting out, but it was too long (IMO) and they introduced more conundrums and plot holes than a barrel of swiss cheese. I left the theater with a sigh, feeling annoyed./R From: Dave Gary <davegary@me.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Sunday, February 22, 2015 6:48 AM Subject: Re: [Utah-astronomy] To call or not to call. That is the question. I have read articles in arxiv concerning Alcubierre’s warp drive. What Alcubierre did (at least this is what I think he did, my powers of reason dwindle by the day) is take various changed metric scenarios for spacetime (i.e., warp scenarios) and calculate the energy requirements for each said transition. I believe he called it “metric engineering”. However, all his energy solutions would not work in the real world because they were calculated to have a negative energy density. In other words, these “warp” scenarios required an exotic, yet to be seen, matter that would supply “negative energy densities“ to achieve his changed metric and not suffer the situation of closed time-like curves inherent within all faster-than-light theoretic constructs. So, I think this smaller, negative-energy mass (the Voyager-sized mass you describe) would have to found or manufactured before any space-time metric engineering solution would be feasible. I wish him luck, warp drive would be cool. However, I don’t think Alcubierre is going to pick up any negative-energy mass at Lowe’s or Home Depot any time soon. Dave
On Feb 21, 2015, at 19:00, Robert Taylor <ratskradmt@gmail.com> wrote:
Look at what NASA has done by actually having people design and work on concepts of an FTL drive which just happens to be similar to the warp drive from Star Trek, yes I know sci-fi and what not but creating a warp bubble around the ship that theoretically does work. Alcubierre’s device worked by distorting space-time, expanding the space behind a ship and contracting the space in front of it to create a ‘warp bubble’ that essentially moves space and time around the object, rather than actually accelerating the craft to impossible speeds. They have even shown that it will not require a mass-energy the size of Jupiter to supply the power but a much smaller mass which they say is the size of the Voyager spacecraft. Humans have not even reached a type I Kardashev level of power and are still a century or two away from that point so it is going to be a long time before we are able to venture out into interstellar space. I remember reading a lot about this a couple of years ago and some of the things we would need to overcome is a shield to protect the crew and ship and a way to dissipate the shock wave travelling in front of the spacecraft as it would have enough energy and mass to wipe out any solar system that was being entered by a ship travelling at speeds faster then the speed of light. Oh well one can dream.
On Sat, Feb 21, 2015 at 5:34 PM, Dave Gary <davegary@me.com> wrote:
The extra dimensions are at the quantum level, if they are there. WMAP and Planck data show the universe to be nearly flat. It is very close to Euclidean in terms of its macroscopic geometry. We are talking about aliens that could, possibly, come take us over and make us their minions. I would assume they would have to be macroscopic in size and make macroscopic-sized instruments of war for us to take notice. At the very least, I would think they would be larger than quantum strings. I think the only way to go, for now, is from the start point to the end point if they are to get here. Anything is possible. I play the probabilities.
Dave
On Feb 21, 2015, at 16:57, Rich Allen <rico@ricosweb.net> wrote:
Einstein's universal speed limit only applies if you pass through all points between your start and end point. We don't know if extra-dimensional travel is possible, but I wouldn't be arrogant enough to say that it's impossible. I also don't believe that extraterrestrial beings have visited our solar system... that kind of energy expenditure likely wouldn't be wasted on covert visits or joy rides that result in crash landings.
As has been stated before, we're already sending out signals. More of them, no matter what the message, won't tip the scales either way.
Rich Allen
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_______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options". _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".