This just one theory. Others state that this isn't the case and is flat (to within 2% anyway - latest WMAP survey results). I believe the general consensus is that the later though I'm sure somebody with a really powerful telescope will take a picture of the back of their own head at some stage to prove them wrong. (This is of course impossible). Some people think the universe is shaped like a doughnut (with an extra dimension sort of way). Some of these people may or may not be called Homer.Nigel Watts said:
- Thread starter michael
- Start date
This is exactly my point, if we believe in this theory we would end up where we came from ie, curved space travel. My question is what lies beyond futher than we can imagine and beyond that and so on. If we are in a buble what is that buble in , another buble?. If so how many bubles are there, as there may be infinite number of bubles which are all within an even bigger buble one has to wonder if there is or will ever be a beginning or an end.Nigel Watts said:
At the moment we can only think as far as the tip of our noses in relation to what may be out there.
Middi.
Apparently, we cant travel faster than the speed of light, if we could then we would be able to travel back in time i.e. if you were able to circumnavigate the globe faster than the speed of light, then you would arrive back at the same point fast enough to see yourself leaving. If you could circumnavigate the globe at twice the speed of light then you would arrive back at the same point so fast that you would be able to watch yourself getting ready to leave. If you multiplied this speed ten fold, then you would probably go back far enough to see a couple of guys constructing an original wattle and daub building in the 17th century.
So maybe that’s the solution to overcoming the second law of thermodynamics and entropy which is ruining our old houses. ‘Time travel’. I.e. find out how to travel faster than the speed of light and we’ll never witness material decay. That oak beam will constantly be as good as the day it was installed.
So maybe that’s the solution to overcoming the second law of thermodynamics and entropy which is ruining our old houses. ‘Time travel’. I.e. find out how to travel faster than the speed of light and we’ll never witness material decay. That oak beam will constantly be as good as the day it was installed.
LadyArowana
Member
- Messages
- 3,687
MdB said:
Why would you need a powerful telescope to take a picture of the back of your head? The esteemed Mr P snapped one with an ordinary camera not long after this was done. Unfortunately I believe Mrs P has made him stop shaving the back of his head and so it is hidden now.
still_adrianth
Member
- Messages
- 27
The law only works for a closed (isolated) system. So by "our world" we have to mean the universe (whatever that is), not the Earth. The law doesn't prohibit increases in order on a local scale (eg earth) for plenty of time. Hence what we see on Earth. We have temporary energy sources such as the sun, nuclear energy, and residual heat in the Earth giving energy to processes that can organise things. Getting out of painting the window frames isn't that easy!
An evolutionary perspective can also assuage worry over the sun dying, Andromeda colliding with the Milky Way, etc, etc. On paleontological evidence, these things are probably going to matter as much to Homo sapiens as the last ice age did to the dinosaurs (though maybe humans are very, very, special).
So there are positives wherever you look!
A.
An evolutionary perspective can also assuage worry over the sun dying, Andromeda colliding with the Milky Way, etc, etc. On paleontological evidence, these things are probably going to matter as much to Homo sapiens as the last ice age did to the dinosaurs (though maybe humans are very, very, special).
So there are positives wherever you look!
A.
citizensmith
Member
- Messages
- 135
- Location
- Herefordshire
I am not sure i want to inhabit a universe where rather irritating & smarmy "plastic" professors try to look young and hip, whilst at the same time being partly responsible for the 90's song "things can only get better" (which should be reason enough for at least a long stretch at her majesty's pleasure).
If that's all there is, then bring on Armageddon!
(oops, that was last week, on another thread wasn't it?)
If that's all there is, then bring on Armageddon!
(oops, that was last week, on another thread wasn't it?)
Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
Oh, all right... if you want my quick, modest explanation of the whole space-time thing, here it is (I don't know why Einstein made such a fuss about it):-
One of the most illuminating ways of understanding the resolution of the so-called "twin paradox" is by analysing carefully drawn, detailed space-time diagrams for specific choices of trip distance and velocity. I have done so below for a trip of three light-years undertaken at a speed of 3/5 c (giving a relativistic factor γ = 5/4) in both directions and with a "turnaround time" of negligible duration. (The approximation of negligible turnaround time may very well lead to anatomically unrealistic "g forces" (!) and can be relaxed at the expense of additional computational complexity, but it makes no qualitative difference in the result.)
In this case the Earth-bound twin (EBT) finds that it takes the travelling twin (TT) five years to reach the destination and five years to return for a total of ten years. During this time the TT's clocks run slow by a factor of 1/γ = 4/5 so that the TT ages by eight years, four years on each leg of the journey, and is, therefore, two years younger at the reunion.
The view from the reference frame of the Earth
The left panel of the figure below (which you can click on to open a larger version in a new window), shows the world-lines of the EBT and the TT in the reference frame of Earth. Note that the TT reaches the destination at a distance of three lightyears after an elapsed time of five years in this frame and that the TT has aged only four years at that point. Note also that the scale of the x and t axes are such that light travels along lines at a 45 degree angle, i.e., 1 year per light year, and that the TT's world-lines have a larger slope (representing a lower speed) of 5/3 years per light year.
Because the figure is drawn from the frame of reference of Earth, horizontal lines represent collections of events that occur at the same time, i.e., "lines of simultaneity" for the EBT. The figure also, however, includes a few lines of simultaneity in the reference frame of the TT as shown in grey. Because of the relativity of simultaneity, these lines are tilted and run from lower left to upper right during the outbound leg and from lower right to upper left during the inbound leg. In both cases the slope is the inverse of that of the TT's world-line, 3/5 years per light year. For instance, note that one of these lines indicates that at the moment the TT sends the third yearly signal, the TT would say that the EBT's clock reads 2.4 years as should be expected since the TT says the EBT's clock is "moving" and, therefore, running slow. Note finally that there are two lines of simultaneity linking the turnaround point, one for the outbound leg and one for the inbound leg. They indicate that the EBT's instant of simultaneity in the TT's frame jumps quickly from 3.2 years to 6.8 years during the turnaround as the TT moves from one reference frame to another.
Both the EBT and the TT send light signals to each other at yearly intervals as shown by the red and blue lines respectively and each transmission is marked with the number of the year at which it was sent. Note that the TT receives only the first two signals from the EBT on the outbound leg and receives all eight remaining signals on the inbound leg with the final, tenth, signal received at the moment of the reunion. Note also that the EBT receives the last of the four outbound signals (including the fourth at the turnaround point) at year eight and receives the four inbound signals during only the last two years.
Thus, we see that the EBT receives signals at the rate of one every two years for the first eight years and then at a rate of two per year for the final two years. This amounts to a total of (1/2)*8 + (2)*2 = 8 signals received from the TT. On the other hand the TT receives signals also at the rate of one every two years for only the first four years and then at a rate of two per year for the final four years. This amounts to a total of (1/2)*4 + (2)*4 = 10 signals received from the EBT.
It is well worth noting the fact that both twins agree that they receive signals at a rate of 1/2 per year (low frequency) when those signals reflect relative motion away from each other and both twins also agree that they receive signals at a rate of 2 per year (high frequency) when those signals reflect relative motion toward each from each other. The difference is that, for the TT, the low and high frequency signals occupy equal portions of the trip while, for the EBT, the low frequency signals are observed during 80% of the trip.
The view from the reference frame of the outbound traveller
The right panel of the figure, shows the world-lines of the EBT and the TT in the outbound reference frame. Note that, in this reference frame, the reunion takes place 12.5 years after the departure in keeping with the fact that the EBT's clocks run slow the entire time. The TT, however, leaves this reference frame at the turnaround point four years into the trip when the EBT's clock reads 3.2 years as previously noted. Note also that the EBT is 2.4 light-years away at this time, the largest separation of the trip in this frame, properly reflecting the Lorentz contraction of the 3 light-year distance observed in the reference frame of Earth.
On the inbound leg, the TT moves at a speed of -15/17 c as obtained from the relativistic addition of the speeds -3/5 c and -3/5 c. During this time the TT's clocks run slow by a factor of 1/γ = 17/8, which is reflected in the fact that it takes just over two years for the TT's clock to advance each additional year. The world-lines for the light signals are again shown along with the lines of simultaneity for the TT and they confirm every feature previously noted in the space-time diagram for the reference frame of Earth.
One of the most illuminating ways of understanding the resolution of the so-called "twin paradox" is by analysing carefully drawn, detailed space-time diagrams for specific choices of trip distance and velocity. I have done so below for a trip of three light-years undertaken at a speed of 3/5 c (giving a relativistic factor γ = 5/4) in both directions and with a "turnaround time" of negligible duration. (The approximation of negligible turnaround time may very well lead to anatomically unrealistic "g forces" (!) and can be relaxed at the expense of additional computational complexity, but it makes no qualitative difference in the result.)
In this case the Earth-bound twin (EBT) finds that it takes the travelling twin (TT) five years to reach the destination and five years to return for a total of ten years. During this time the TT's clocks run slow by a factor of 1/γ = 4/5 so that the TT ages by eight years, four years on each leg of the journey, and is, therefore, two years younger at the reunion.
The view from the reference frame of the Earth
The left panel of the figure below (which you can click on to open a larger version in a new window), shows the world-lines of the EBT and the TT in the reference frame of Earth. Note that the TT reaches the destination at a distance of three lightyears after an elapsed time of five years in this frame and that the TT has aged only four years at that point. Note also that the scale of the x and t axes are such that light travels along lines at a 45 degree angle, i.e., 1 year per light year, and that the TT's world-lines have a larger slope (representing a lower speed) of 5/3 years per light year.
Because the figure is drawn from the frame of reference of Earth, horizontal lines represent collections of events that occur at the same time, i.e., "lines of simultaneity" for the EBT. The figure also, however, includes a few lines of simultaneity in the reference frame of the TT as shown in grey. Because of the relativity of simultaneity, these lines are tilted and run from lower left to upper right during the outbound leg and from lower right to upper left during the inbound leg. In both cases the slope is the inverse of that of the TT's world-line, 3/5 years per light year. For instance, note that one of these lines indicates that at the moment the TT sends the third yearly signal, the TT would say that the EBT's clock reads 2.4 years as should be expected since the TT says the EBT's clock is "moving" and, therefore, running slow. Note finally that there are two lines of simultaneity linking the turnaround point, one for the outbound leg and one for the inbound leg. They indicate that the EBT's instant of simultaneity in the TT's frame jumps quickly from 3.2 years to 6.8 years during the turnaround as the TT moves from one reference frame to another.
Both the EBT and the TT send light signals to each other at yearly intervals as shown by the red and blue lines respectively and each transmission is marked with the number of the year at which it was sent. Note that the TT receives only the first two signals from the EBT on the outbound leg and receives all eight remaining signals on the inbound leg with the final, tenth, signal received at the moment of the reunion. Note also that the EBT receives the last of the four outbound signals (including the fourth at the turnaround point) at year eight and receives the four inbound signals during only the last two years.
Thus, we see that the EBT receives signals at the rate of one every two years for the first eight years and then at a rate of two per year for the final two years. This amounts to a total of (1/2)*8 + (2)*2 = 8 signals received from the TT. On the other hand the TT receives signals also at the rate of one every two years for only the first four years and then at a rate of two per year for the final four years. This amounts to a total of (1/2)*4 + (2)*4 = 10 signals received from the EBT.
It is well worth noting the fact that both twins agree that they receive signals at a rate of 1/2 per year (low frequency) when those signals reflect relative motion away from each other and both twins also agree that they receive signals at a rate of 2 per year (high frequency) when those signals reflect relative motion toward each from each other. The difference is that, for the TT, the low and high frequency signals occupy equal portions of the trip while, for the EBT, the low frequency signals are observed during 80% of the trip.
The view from the reference frame of the outbound traveller
The right panel of the figure, shows the world-lines of the EBT and the TT in the outbound reference frame. Note that, in this reference frame, the reunion takes place 12.5 years after the departure in keeping with the fact that the EBT's clocks run slow the entire time. The TT, however, leaves this reference frame at the turnaround point four years into the trip when the EBT's clock reads 3.2 years as previously noted. Note also that the EBT is 2.4 light-years away at this time, the largest separation of the trip in this frame, properly reflecting the Lorentz contraction of the 3 light-year distance observed in the reference frame of Earth.
On the inbound leg, the TT moves at a speed of -15/17 c as obtained from the relativistic addition of the speeds -3/5 c and -3/5 c. During this time the TT's clocks run slow by a factor of 1/γ = 17/8, which is reflected in the fact that it takes just over two years for the TT's clock to advance each additional year. The world-lines for the light signals are again shown along with the lines of simultaneity for the TT and they confirm every feature previously noted in the space-time diagram for the reference frame of Earth.
Flyfisher
Member
- Messages
- 10,200
- Location
- Norfolk, UK
I prefer Groucho Marx's summary: "Time flies like an arrow, fruit flies like a banana"
Blimey !!!, mr P , you have really thrown the spanner in the works now.
How does a poor blind man from birth that does not now what is light is going to make sense of it all.
Does that mean then that the laws of physics regarding the speed of light and travel only apply to creatures that can see and invent a system ( e=mc2 and all that) to try and understand how it all works whereby it does not really matter to any other heavenly body or other earthly matter and creatures ( and blind creatures) because everything is totally irrelevant
( please keep things simple next time you reply to a scientific question, I nearly had a nervous breakdown at the thought that if I could travel faster then the speed of light i could ask someone to paint the windows before I made them)
Middi
How does a poor blind man from birth that does not now what is light is going to make sense of it all.
Does that mean then that the laws of physics regarding the speed of light and travel only apply to creatures that can see and invent a system ( e=mc2 and all that) to try and understand how it all works whereby it does not really matter to any other heavenly body or other earthly matter and creatures ( and blind creatures) because everything is totally irrelevant
( please keep things simple next time you reply to a scientific question, I nearly had a nervous breakdown at the thought that if I could travel faster then the speed of light i could ask someone to paint the windows before I made them)
Middi
Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
Pah! People never said that about Einstein.
Maybe Douglas Adams was right all along. The answer to life and everything is “42”.
Nevertheless, the laws of physics do seem to demonstrate that the cycle of entropy (all matter moving from a state of order to its natural state of decay) will continue and we and generations after us will always be fighting a loosing battle in trying to maintain the very existence of our old buildings.
Nevertheless, the laws of physics do seem to demonstrate that the cycle of entropy (all matter moving from a state of order to its natural state of decay) will continue and we and generations after us will always be fighting a loosing battle in trying to maintain the very existence of our old buildings.
LadyArowana
Member
- Messages
- 3,687
michael said:
It's also very likely that God's Final Message to His Creation will indeed be "We apologise for the inconvenience" written in letters of fire.
Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
To be absolutely accurate, that was Deep Thought's answer to the great question of life, the universe and everything. The tricky bit was defining the question. :wink:michael said:
Flyfisher
Member
- Messages
- 10,200
- Location
- Norfolk, UK
Indeed, which is why the Earth was built in the hope of finding the ultimate question, though the plan was somewhat upset when the Vogons destroyed the Earth before the answer, er the question, could be determined.
I suggest booking a table at Milliways and hoping that all will be eventually revealed.
I suggest booking a table at Milliways and hoping that all will be eventually revealed.
Penners
Member
- Messages
- 17,294
- Location
- Suffolk, England
Well yes, but in fairness planning consent for the hyperspace bypass project had been sought and the plans had been available for inspection beforehand.Flyfisher said:
It's just a pity that Earth was never listed. Laziness on the part of Terrestrial Heritage, if you ask me.