4 of 8
4
Poll
How you rate it ?
Possible... Propability indeterminate... 10
Possible... but very unlikely... 24
Absolutely impossible... 4
Total Votes: 38
You must be a logged-in member to vote
UFO/ET… How sceptic are you ?
Posted: 21 October 2010 03:41 PM   [ Ignore ]   [ # 46 ]
Moderator
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5551
Joined  2010-06-16

Another characteristic that may hinder a planet in developing life beyond everything DarronS has said, is the lack of a moon.  Even if the planet has all the other things needed, including a large amount of water, if it just sits there without much stirring, the level of mixing and the liklihood of the myriad and complex chemical reactions needed to generate life would be far, far less, reducing that probability to much, much less.

Occam

 Signature 

Succinctness, clarity’s core.

Profile
 
 
Posted: 21 October 2010 03:53 PM   [ Ignore ]   [ # 47 ]
Sr. Member
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  7684
Joined  2008-04-11

Funny you should mention that. There was a great program on the science channel last week pointing that out. Not only a moon, but a moon of the proper size. We are losing our moon by cm/year. When our moon finally leaves the gravitational grasp of our planet…our world will be a very different place.

 Signature 

Church; where sheep congregate to worship a zombie on a stick that turns into a cracker on Sundays…

Profile
 
 
Posted: 21 October 2010 03:56 PM   [ Ignore ]   [ # 48 ]
Moderator
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5551
Joined  2010-06-16

Yeah, but we won’t have to worry about it.  By then our species will almost certainly be supplanted by something else. 

Occam

 Signature 

Succinctness, clarity’s core.

Profile
 
 
Posted: 21 October 2010 04:00 PM   [ Ignore ]   [ # 49 ]
Sr. Member
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  7684
Joined  2008-04-11
Occam. - 21 October 2010 03:56 PM

Yeah, but we won’t have to worry about it.  By then our species will almost certainly be supplanted by something else. 

Occam

Unfortunately true. I don’t think the age of humans will last as long as the age of the dinosaurs.

 Signature 

Church; where sheep congregate to worship a zombie on a stick that turns into a cracker on Sundays…

Profile
 
 
Posted: 21 October 2010 04:10 PM   [ Ignore ]   [ # 50 ]
Sr. Member
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  4812
Joined  2007-10-05

psikey, there is such a chart in my astronomy text, but that doesn’t do y’all much good. I found one here that isn’t quite as clear, will give you an idea of our stellar neighborhood. There are more than 130 stars and brown dwarfs (gas clouds too small to kick off nuclear fusion) within 20 LY of Earth. The most interesting for this discussion is, Delat Pavonis, a prime target for NASA’s proposed Terrestrial Planet Finder mission. D Pavonis is older than our Sun and probably too hot and unstable to harbor complex life. Maybe we’ll find signs of an ancient civilization if we ever send a spacecraft that way.

The asteroid as spacecraft idea seems like a good idea, but there are still problems. Traveling within our solar system requires a very strong magnetic field to deflect the deadly rays our own Sun produces, and the Sun shields us from extra solar cosmic radiation. Leaving the Sun’s protective cocoon will require careful shielding, not to mention numerous spare parts and reliability orders of magnitude greater than anything we have developed so far. These are tremendous engineering challenges. Then there is the whole energy source problem to overcome. Accelerating a Space Shuttle size object to 20 percent the speed of light would take more energy than is available in our entire solar system using conventional rocket fuels. Anti-matter drives require more energy input than output. Nuclear fusion seems the best alternative, but fusion has been 20 years off for the last 30 years or so, and any conceivable fusion power plant would be huge, raising the power requirements even more. Power requirements go up by the square of the mass you are trying to accelerate.

Which gets me back to the question no one has been able to answer. If there are space-faring civilizations out there why haven’t we detected them? Even if they did not come to our solar system the energy expended would be detectable from a long way off.

As for our radio transmissions, they are so feeble they will get lost in interstellar background noise long before they reach the nearest star system. There isn’t anyone out there watching listening the War of the Worlds.

 Signature 

“In the beginning, God created the universe. This has made many people very angry and has been widely regarded as a bad move.”
Douglas Adams, The Restaurant at the End of the Universe

Profile
 
 
Posted: 23 October 2010 12:45 AM   [ Ignore ]   [ # 51 ]
Member
RankRankRankRankRankRankRankRank
Total Posts:  191
Joined  2010-10-09

Force = mass x acceleration, and power = force x velocity

Thus power = mass x velocity x acceleration, or P = mvdv/dt                                                      

So Power is a linear function of mass, not a squared function. Double the mass, double the power requirements.

[ Edited: 23 October 2010 12:52 AM by Theflyingsorcerer ]
Profile
 
 
Posted: 23 October 2010 05:53 AM   [ Ignore ]   [ # 52 ]
Sr. Member
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  4812
Joined  2007-10-05

You are right. Thanks for the correction.

 Signature 

“In the beginning, God created the universe. This has made many people very angry and has been widely regarded as a bad move.”
Douglas Adams, The Restaurant at the End of the Universe

Profile
 
 
Posted: 23 October 2010 07:14 AM   [ Ignore ]   [ # 53 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  967
Joined  2005-01-14
Theflyingsorcerer - 20 October 2010 12:35 PM

“Any KNOWN means of propulsion.” Exactly…....

I’m not sure what you’re getting at here, but my feeling is that if no known means of propulsion can explain the thing, it may be worth at least considering that what people think they saw was an optical illusion.  The most generally accepted theory among the skeptical community is that instead of one massive 1,500 foot long craft, what they really saw was the lights of three ordinary airplanes flying in formation.  The witnesses merely “connected the dots” and thought they saw a structure in between them.  In fact, one of the eyewitnesses in the program I mentioned even stated that when the “craft” flew in front of the full moon, the “hull” seemed to go all transparent!  That should have been a dead giveaway, but the “investigators” completely ignored it.

The explanation for the thing’s silence is simple—it was merely flying at a much higher altitude that the witnesses thought it was.  As a matter of fact, I’m almost certain that the pilots of the five aircraft even confessed to the hoax, but again there was no mention on this program.

The aircraft flares which somebody else mentioned was actually another sighting much later the same night, and may have been completely unrelated.

Profile
 
 
Posted: 08 November 2010 06:13 PM   [ Ignore ]   [ # 54 ]
Jr. Member
Rank
Total Posts:  2
Joined  2010-11-08

Though it has not been proved, it would be a logical thinking that in such a vast and ever expanding universe where we actually live, and adding to that, the already long existence of 4,000 million years it posses, not only one race of intelligent living beings could have developed, even narrowing it down to existence of life as we know it.

Why would we be an unique sand grain in the whole Sahara desert?

Just logical thinking, but even logic can be wrong…

Profile
 
 
Posted: 08 November 2010 06:50 PM   [ Ignore ]   [ # 55 ]
Sr. Member
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  6054
Joined  2009-02-26

No one has yet addressed the possibility of sending robots for exploration. Time becomes less relevant in such a scenario. Robots can remain inactive for millenia, then become activated when the ship’s sensors detect life on a planet. I realize it would not be useful for the civilization sending them, but technologically it would be possible and relatively much cheaper.

 Signature 

Art is the creation of that which evokes an emotional response, leading to thoughts of the noblest kind.
W4U

Profile
 
 
Posted: 08 November 2010 08:07 PM   [ Ignore ]   [ # 56 ]
Jr. Member
Rank
Total Posts:  2
Joined  2010-11-08
Write4U - 08 November 2010 06:50 PM

No one has yet addressed the possibility of sending robots for exploration. Time becomes less relevant in such a scenario. Robots can remain inactive for millenia, then become activated when the ship’s sensors detect life on a planet. I realize it would not be useful for the civilization sending them, but technologically it would be possible and relatively much cheaper.

That’s a good approach Write4U, but “robots can remain inactive for millenia”, it is true, but trying to re-activate them when such event happens might be from difficult to impossible.  What will power the robots?  After millenia, even the best batteries, which is now the best instant power source, could be dead.

Another mechanism of keeping an eternal source of electrical power must be used and away from the sun, other experiments for this must be done.

Profile
 
 
Posted: 08 November 2010 09:55 PM   [ Ignore ]   [ # 57 ]
Sr. Member
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  6054
Joined  2009-02-26
Tech - 08 November 2010 08:07 PM
Write4U - 08 November 2010 06:50 PM

No one has yet addressed the possibility of sending robots for exploration. Time becomes less relevant in such a scenario. Robots can remain inactive for millenia, then become activated when the ship’s sensors detect life on a planet. I realize it would not be useful for the civilization sending them, but technologically it would be possible and relatively much cheaper.

That’s a good approach Write4U, but “robots can remain inactive for millenia”, it is true, but trying to re-activate them when such event happens might be from difficult to impossible.  What will power the robots?  After millenia, even the best batteries, which is now the best instant power source, could be dead.

Another mechanism of keeping an eternal source of electrical power must be used and away from the sun, other experiments for this must be done.

The same mechanism that “wakes” the robots can be used to “trigger” mixing of stored chemicals which then generate power. The ship itself is a robot and may be designed to receive and store power from external sources, heat, light, hydrogen, oxygen, or what have you.

[ Edited: 09 November 2010 06:35 AM by Write4U ]
 Signature 

Art is the creation of that which evokes an emotional response, leading to thoughts of the noblest kind.
W4U

Profile
 
 
Posted: 09 November 2010 05:57 AM   [ Ignore ]   [ # 58 ]
Sr. Member
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  6054
Joined  2009-02-26

Now that I think of it. Has anyone ever thought of designing a type of battery that uses a dry chemical mix. I am not sure how that could be accomplished, but it might make for a portable energy source which can be activated on site. Similar to the cranking of a handle in a flashlight or walkie talkie. Dry chemicals are light, stable and would be naturally enclosed and protected by the battery’s shell.

 Signature 

Art is the creation of that which evokes an emotional response, leading to thoughts of the noblest kind.
W4U

Profile
 
 
Posted: 09 November 2010 06:05 AM   [ Ignore ]   [ # 59 ]
Sr. Member
Avatar
RankRankRankRankRankRankRankRankRankRank
Total Posts:  6054
Joined  2009-02-26
Theflyingsorcerer - 23 October 2010 12:45 AM

Force = mass x acceleration, and power = force x velocity

Thus power = mass x velocity x acceleration, or P = mvdv/dt                                                      

So Power is a linear function of mass, not a squared function. Double the mass, double the power requirements.

Even if it is a linear function, at or near SOL the increase in mass would still require incredible energy.

Doesn’t the exponential function have something to do with this also?

[ Edited: 09 November 2010 06:29 AM by Write4U ]
 Signature 

Art is the creation of that which evokes an emotional response, leading to thoughts of the noblest kind.
W4U

Profile
 
 
Posted: 09 November 2010 11:35 PM   [ Ignore ]   [ # 60 ]
Jr. Member
Avatar
Rank
Total Posts:  13
Joined  2010-11-09

Power is work divided by time therefore work =Pt.
Power is not “power = force x velocity” as postulated but the amount of energy per second. which is given in Watts.  This is the energy per second.

work = force x distance so say you had a 1 Newton force which moved 1 metre the work is 1kgm2/s2
5a7bafd39df0c3d608bc63863dddc1b9.png

Instantaneous power can be given by the following function
8f5a95a95ef23ece175e2c1f590b9802.png

[ Edited: 09 November 2010 11:45 PM by VenomFangX ]
 Signature 

My advice to you is get married: if you find a good wife you’ll be happy; if not, you’ll become a philosopher. - Socrates

Profile
 
 
   
4 of 8
4