As I think we are going off topic, please see my response here: http://www.singastro.org/viewtopic.php? ... highlight=
Cheers!
How would time and date be calculated if...
Very interesting questions, really sets me thinking.. 
I think that as long as there are suns and moons (or any heavenly objects), 'time and date' will still exist. However, to say that our Earth orbits a binary star and has many moons, this will result in many complex implications. In this case, the definition of time itself will take on a whole new form of meaning too.
From a primitive view, if early civilisations were still allowed to exist under such strong differential gravitational forces pulling on Earth, then they would see 2 suns rising and setting in the same manner that we already experience with our own Sun. Of course, there will be occasions when one of the stars gets hidden behind the other. Even that, I don't see why sundials can't be used. In fact, I think their definition of time will become even more specific and accurate than what we currently know of. Here's why:
If they used a sundial similar to ours, they will see 2 shadows cast instead of only 1. Furthermore, assuming that one of the stars would orbit faster than the other, so will the shadow cast by the sundial be affected too. The end result would be observing 2 shadows cast, with one changing positions at shorter intervals. This would almost be similar to the clockwork we already know about, with perhaps one being the 'minute' hand, while the other, 'hour' hand. Do we get that for our sundials? Not that I currently know of any at the moment.. Of course, in the process, we can expect that the positions of the shadows will vary over time for those civilisations, but all the more, the difference might just denote the different months in their definition of a year.
A major problem arises however, if civilisations on the Northern and Southern hemispheres were to come to an agreement on an 'official' time. In fact, from their point of view, time on the Northern Hemisphere will never be the same as the time observed by those in the South. Similar to what we currently observe of the different constellations in the 2 hemispheres, what we see in the North is not what we would expect to see in the South. In the South, all the constellations will appear to be flipped upside down. Using this analogy, stars which are presumably higher in the sky in one hemisphere would instead be lower in the sky in another hemisphere. Therefore, if the suns (binary star) were used to denote a particular time, confusion will arise amongst the civilisations. How they would eventually resolve this is out of my reach and neither do I think this will even happen now or ever in our own world.. :roll: In my opinion, one thing however, is that the civilisations on this illustrated Earth may just discover the 5th Dimension due to such differences relating to their definition of time.
What about date if Earth has more than 1 moon? Actually, Earth has 2 moons, one of which is Cruithne, but it didn't affect us and we still have 'date'?
Alright, alright.. it isn't exactly a real moon but an asteroid captured by Earth's gravity, but even that, its partial orbit of the Earth is not permanent. We hardly even see Cruithne due to its slow and strange orbit w.r.t Earth's, hence we only see 1 moon.
If Earth had multiple moons like Jupiter and Saturn, even the definitions of life itself, apart from date, would change too. Subject to the strong differential gravitational forces induced by the moons as well as the binary star (since the gravity comes from objects of opposing sides), large tidal forces will result which will then distort the Earth, threatening to tear it into pieces. An example of how great an impact these tidal forces can inflict on Earth can be observed by the tidal forces exerted by Jupiter on its moon, Io, whereby the intensity of these are so large that the solid surface of Io is raised and lowered by hundreds of meters twice in each rotational period. This motion heats up the interior of Io so much that it is probably mostly molten and as a consequence, Io is covered with active volcanoes and is geologically the most active object in the Solar System.
If civilisations were still allowed to exist in such hostile environments (I’m not ruling out the possibility), then of course they would live to see the multiple moons waxing and waning at various stages on different nights. Using the same analogy of the sundial and the shadows mentioned earlier on, the different phases of the moons on a single night can possibly be used to denote a specific day, week, month, year, so on and so forth. Thus, date in this case will also become more specific and accurate and will most likely take on a different form of meaning as well.
The moons may not necessarily be used to tell date too. In my opinion, if water can still exist as a liquid state in such an environment, then the tides of oceans and seas could probably be used to tell the date and perhaps even time, since the moons will have varying effects on their gravitational pull on Earth which causes the high and low tides.
As to whether or not Life is indeed possible under such peculiar circumstances (binary star systems) whereby the fabric of space-time would be so strangely warped, that will be another topic in another thread.
Cheers,
:cheers:
- ALPiNe
I think that as long as there are suns and moons (or any heavenly objects), 'time and date' will still exist. However, to say that our Earth orbits a binary star and has many moons, this will result in many complex implications. In this case, the definition of time itself will take on a whole new form of meaning too.From a primitive view, if early civilisations were still allowed to exist under such strong differential gravitational forces pulling on Earth, then they would see 2 suns rising and setting in the same manner that we already experience with our own Sun. Of course, there will be occasions when one of the stars gets hidden behind the other. Even that, I don't see why sundials can't be used. In fact, I think their definition of time will become even more specific and accurate than what we currently know of. Here's why:
If they used a sundial similar to ours, they will see 2 shadows cast instead of only 1. Furthermore, assuming that one of the stars would orbit faster than the other, so will the shadow cast by the sundial be affected too. The end result would be observing 2 shadows cast, with one changing positions at shorter intervals. This would almost be similar to the clockwork we already know about, with perhaps one being the 'minute' hand, while the other, 'hour' hand. Do we get that for our sundials? Not that I currently know of any at the moment..
Of course, in the process, we can expect that the positions of the shadows will vary over time for those civilisations, but all the more, the difference might just denote the different months in their definition of a year. A major problem arises however, if civilisations on the Northern and Southern hemispheres were to come to an agreement on an 'official' time. In fact, from their point of view, time on the Northern Hemisphere will never be the same as the time observed by those in the South. Similar to what we currently observe of the different constellations in the 2 hemispheres, what we see in the North is not what we would expect to see in the South. In the South, all the constellations will appear to be flipped upside down. Using this analogy, stars which are presumably higher in the sky in one hemisphere would instead be lower in the sky in another hemisphere. Therefore, if the suns (binary star) were used to denote a particular time, confusion will arise amongst the civilisations. How they would eventually resolve this is out of my reach and neither do I think this will even happen now or ever in our own world.. :roll: In my opinion, one thing however, is that the civilisations on this illustrated Earth may just discover the 5th Dimension due to such differences relating to their definition of time.
What about date if Earth has more than 1 moon? Actually, Earth has 2 moons, one of which is Cruithne, but it didn't affect us and we still have 'date'?
Alright, alright.. it isn't exactly a real moon but an asteroid captured by Earth's gravity, but even that, its partial orbit of the Earth is not permanent. We hardly even see Cruithne due to its slow and strange orbit w.r.t Earth's, hence we only see 1 moon.If Earth had multiple moons like Jupiter and Saturn, even the definitions of life itself, apart from date, would change too. Subject to the strong differential gravitational forces induced by the moons as well as the binary star (since the gravity comes from objects of opposing sides), large tidal forces will result which will then distort the Earth, threatening to tear it into pieces. An example of how great an impact these tidal forces can inflict on Earth can be observed by the tidal forces exerted by Jupiter on its moon, Io, whereby the intensity of these are so large that the solid surface of Io is raised and lowered by hundreds of meters twice in each rotational period. This motion heats up the interior of Io so much that it is probably mostly molten and as a consequence, Io is covered with active volcanoes and is geologically the most active object in the Solar System.
If civilisations were still allowed to exist in such hostile environments (I’m not ruling out the possibility), then of course they would live to see the multiple moons waxing and waning at various stages on different nights. Using the same analogy of the sundial and the shadows mentioned earlier on, the different phases of the moons on a single night can possibly be used to denote a specific day, week, month, year, so on and so forth. Thus, date in this case will also become more specific and accurate and will most likely take on a different form of meaning as well.
The moons may not necessarily be used to tell date too. In my opinion, if water can still exist as a liquid state in such an environment, then the tides of oceans and seas could probably be used to tell the date and perhaps even time, since the moons will have varying effects on their gravitational pull on Earth which causes the high and low tides.
As to whether or not Life is indeed possible under such peculiar circumstances (binary star systems) whereby the fabric of space-time would be so strangely warped, that will be another topic in another thread.
Cheers,
:cheers:
- ALPiNe