Caveman 2 Cosmos

[Yudishtira]

Almost none of the SciFi franchises dismiss Einstein. Star Trek warp drives compress spacetime in front of the ship, and expand it behind. The ship itself doesn't actually move. It just surfs on a wave.

Star wars and stargate both have the ship enter "hyperspace", and leave our spacetime entirely. Battlestar galactica uses "fold", or "jump" drives that basically create an artificial worm hole allowing the ship to just jump to its destination instantly.

My point is none of them simply accelerate to light speed and beyond like what is being discussed here. Even if that was possible the time dilation makes it more akin to a time machine and worthless.

I'm a big scifi fan, but FTL is most likely impossible.

Okay they don't accelerate to lightspeed and/or beyond. Nevertheless they get where they're going faster than light normally makes that journey. That is FTL travel.

A very Einsteinian way of doing it would be to curve space until your destination was much closer, eg. bring your destination exoplanet to a few hundred thousand kilometres away.

 

[Thunderbrd]

Fun fact: All photons always travel at same speed in vacuum no matter what reference frame you pick - just directions and energies would be different.

And if you can say that, then it has a speed. If it has a speed that it can travel, it is not instantaneous arrival wherever it points.

I'm aware that speed is constant, which is certainly an interesting property of light. I have to wonder, is it the only energy WITH a constant speed? Is this unusual for waves or is it par for course standard behavior?

This also becomes problematic when you view light as travelling at the speed of causality itself:

It is widely accepted that there is nothing that can travel that a speed greater than light due to Einstein's theory of relativity. But from observational analysis of black holes it can be said that not even light can escape the event horizon of one.

 

[tmv]

And if you can say that, then it has a speed. If it has a speed that it can travel, it is not instantaneous arrival wherever it points.

It is ... a matter of perspective (and probably one of the only times this saying is correct). Special Relativity discards the concept of universal simultaneity. This is perhaps the strangest aspect of it.

What does this mean? It means we lose the concept of a universal clock. Clocks are tied to moving frames of reference (this has nothing to do with illusions, by the way). There is a clock tied to a ray of light that goes from A to B, but this clock never ticks. From its own perspective, the ray of light moves instantaneously.

If there is an observer (in this case: Just about anyone or anything that you can define a frame of reference around), this observer has a clock as well. If the observer doesn't move with the speed of light, this clock will tick. And the observer can watch the ray of light, experience time passing, and thus attribute to this ray of light a finite speed.

Black holes are inescapable for both matter and light, that is what sets them apart from any other object in nature. Nothing can get out of a black hole.This remains true even in Modern Physics, because Hawking Radiation does not originate from within the black hole.

 

[Thunderbrd]

It is ... a matter of perspective (and probably one of the only times this saying is correct). Special Relativity discards the concept of universal simultaneity. This is perhaps the strangest aspect of it.

What does this mean? It means we lose the concept of a universal clock. Clocks are tied to moving frames of reference (this has nothing to do with illusions, by the way). There is a clock tied to a ray of light that goes from A to B, but this clock never ticks. From its own perspective, the ray of light moves instantaneously.

If there is an observer (in this case: Just about anyone or anything that you can define a frame of reference around), this observer has a clock as well. If the observer doesn't move with the speed of light, this clock will tick. And the observer can watch the ray of light, experience time passing, and thus attribute to this ray of light a finite speed.

Black holes are inescapable for both matter and light, that is what sets them apart from any other object in nature. Nothing can get out of a black hole.This remains true even in Modern Physics, because Hawking Radiation does not originate from within the black hole.

Ok, so from a 3rd party measuring the speed perspective, the speed of light can be exceeded because it can be measured as something that requires time from the outside looking in. Let's for a moment consider that it may not matter what the experience is to the light itself in this regard.

Additionally, if we accept that we have lost the concept of a universal clock, then we have already completely abandoned the idea that causality even has any integrity in so doing.

 

[Donoya]

Damn... My game installation is missing a bunch of files after my computer was recovered from being bricked, and I was going to use my disk to reinstall everything, but I went on vacation. And then it burned up in a storage fire! (along with a bunch of other stuff) I wish I could play this mod again... does the mod work if I rebuy the game on steam?

 

[Thunderbrd]

Damn... My game installation is missing a bunch of files after my computer was recovered from being bricked, and I was going to use my disk to reinstall everything, but I went on vacation. And then it burned up in a storage fire! (along with a bunch of other stuff) I wish I could play this mod again... does the mod work if I rebuy the game on steam?

Quite a string of bad luck there. Sorry to hear that. Yes, it works but IIRC there's a better way to get it for this - can't recall what that was tho.

Gog... that was it. Thanks Toffer!

 

[Toffer90]

Damn... My game installation is missing a bunch of files after my computer was recovered from being bricked, and I was going to use my disk to reinstall everything, but I went on vacation. And then it burned up in a storage fire! (along with a bunch of other stuff) I wish I could play this mod again... does the mod work if I rebuy the game on steam?

Both steam and GOG versions are fine for mods.

I recommend the one from https://www.gog.com/game/sid_meiers_civilization_iv_the_complete_edition
It's a bit expensive there atm though.

If you get the steam version you will need to opt into the beta version of it to get the original firaxis release that work with C2C. (steam made a patch for it that breaks C2C ^^)

 

[tmv]

Ok, so from a 3rd party measuring the speed perspective, the speed of light can be exceeded because it can be measured as something that requires time from the outside looking in. Let's for a moment consider that it may not matter what the experience is to the light itself in this regard.

I think you got it the wrong way round. The inside perspective can allow for a greater effective speed, which has to do with length contraction. The outside perspective cannot perceive length contraction, and so will not see anything moving faster than light. This also explains time dilatation - for the moving person the journey appears to be much shorter, and can thus be completed in short time, whereas for the stationary person the journey appears in its full length, and the time elapsed will be greater (possibly much greater if the moving speed was close to the speed of light).

Additionally, if we accept that we have lost the concept of a universal clock, then we have already completely abandoned the idea that causality even has any integrity in so doing.

Only if the non-universal clocks allowed for two events to cause each other depending on the frame of reference. This is indeed a major point in Relativity, and preventing this from happening goes right to its core. If we accept for a moment that for one event to cause the other one these two events must be connected in a way that you can go from the first to the second one without going beyond the speed of light (!), it turns out that you cannot find any frame of reference where you could connect these two events the other way around with this principle. Indeed, if you can connect two events like this, you cannot even find any frame of reference where the second event precedes the first, no matter the speed on a connecting curve.

For any point in spacetime the rest of it fall into three different regions: There are those points that can be reached from the reference point on a strictly sub-luminal curve (these are points that can be influenced from our point of reference - future), then there are points from which the point of reference can be reached on a strictly sub-luminal curve (these points can influence "us" on the point of reference - past), and then there are all the other points, which cannot connect in any way to the point of reference without going beyond the speed of light at least somewhere on the curve. There can be no cause-effect-relationships between any two points that obey this condition. On the other hand, they can appear to be simultaneous to some clock. Indeed, only those points in the third region can be simultaneous to the reference point.

For a more complete explanation I can only refer to https://en.wikipedia.org/wiki/Minkowski_diagram because this needs some diagrams to understand it properly.

 

[Thunderbrd]

for the moving person the journey appears to be much shorter, and can thus be completed in short time, whereas for the stationary person the journey appears in its full length, and the time elapsed will be greater (possibly much greater if the moving speed was close to the speed of light).

Which is itself, for the moving person, time travel, since the observer's frame of reference doesn't change but the person moving experiences none of the passage of time. At least, in the sense that if I traveled 5 light years at the speed of light, I'd be the same age when arriving and the people at my destination would be 5 years older and it would actually be 5 years after I began my nearly instantaneous journey.

That would then suggest that if I turned around and traveled back to my original position, it would now be 10 years after I left though I had not experienced any passage of time. That's time travel itself. Now we've determined we can time travel forward, just not backward.

Here's the thing.

If an object takes 10 seconds to move from point a to point b, then an object that takes 5 seconds to move from point a to point b is faster. Therefore, who cares for a moment what the object experiences or how much time it seems to be to the object to move from point a to point b, if an object takes ANY time to pass from point a to point b, another object, moving faster, can exist. Thus, if we can say that light takes 5 years to get from distant star to Earth, then it is conceivable that another faster object can exist because we can't say as soon as the light emerges, we see it, no matter how distant. To say that nothing can possibly travel faster is... completely illogical. Getting into what the object itself experiences has nothing to do with that. If light were to move at the speed of causality itself, anywhere it could be seen from the moment it exists, it would be seen. There would never be a delay in reaching it's target, or even a measurable speed. It would be immediate.

I'll look at the diagram you posted soon - maybe that will clarify things.


EDIT: Has modern physics completely abandoned the entire idea of Tachyons at this point?

 

[tmv]

Which is itself, for the moving person, time travel, since the observer's frame of reference doesn't change but the person moving experiences none of the passage of time. At least, in the sense that if I traveled 5 light years at the speed of light, I'd be the same age when arriving and the people at my destination would be 5 years older and it would actually be 5 years after I began my nearly instantaneous journey.

That would then suggest that if I turned around and traveled back to my original position, it would now be 10 years after I left though I had not experienced any passage of time. That's time travel itself. Now we've determined we can time travel forward, just not backward.

Correct. This is pretty much the contents of the https://en.wikipedia.org/wiki/Twin_paradox .

If an object takes 10 seconds to move from point a to point b, then an object that takes 5 seconds to move from point a to point b is faster. Therefore, who cares for a moment what the object experiences or how much time it seems to be to the object to move from point a to point b, if an object takes ANY time to pass from point a to point b, another object, moving faster, can exist. Thus, if we can say that light takes 5 years to get from distant star to Earth, then it is conceivable that another faster object can exist because we can't say as soon as the light emerges, we see it, no matter how distant. To say that nothing can possibly travel faster is... completely illogical. Getting into what the object itself experiences has nothing to do with that. If light were to move at the speed of causality itself, anywhere it could be seen from the moment it exists, it would be seen. There would never be a delay in reaching it's target, or even a measurable speed. It would be immediate.

First of all, we get into trouble here with everyday speech. It is often said that the light of stars is so-and-so many years old (and thus we are looking into the past), but that is not strictly true. The present is defined by the concept of simultaneity, and that is variable. There is even a frame of reference where the light we see is from present time, and that is the frame of reference of this ray of light itself. I think this is one of the least understood concepts of Special Relativity (for once it is important to make a distinction from General Relativity).

One of the most important terms in Special Relativity (perhaps the most important one if we only consider terms that were introduced in this theory) is Spacetime. Space and time are considered to be parts of one entity, in many cases these cannot be watched as separate. There are no points in space, only points in space and time (which we call events). If we want to consider a certain movement, we watch the starting and the end event (even more precisely: every single event this movement passes). We have to consider if these two events can be connected by a moving object, and this entire movement can become impossible simply as a property of these events (namely, if this movement would require going beyond the speed of light). In this way, the lion's share of Special Relativity is Geometry.

Tachyons are not ruled out by Relativity, but they have never been watched. They are also less useful than one might think, because these particles (if they exist) could never be slower than the speed of light. I suppose that would make them really hard to control.

 

[Thunderbrd]

First of all, we get into trouble here with everyday speech. It is often said that the light of stars is so-and-so many years old (and thus we are looking into the past), but that is not strictly true. The present is defined by the concept of simultaneity, and that is variable. There is even a frame of reference where the light we see is from present time, and that is the frame of reference of this ray of light itself. I think this is one of the least understood concepts of Special Relativity (for once it is important to make a distinction from General Relativity).

This COULD all make sense if we're talking about something that is obviously true based on observations on a truly intersolar magnitude that we'd somehow have to be able to map, which perhaps we think we have ways to do.

However...

Is it not possible to 'clock' how long it takes for the emergence of light to reach from emergence point A to receiving point B? If I shoot a laser at the moon and have it bounce back, it's taking actual time to return that can be measured (from the moment the laser is turned on to the moment it hits the point of return), therefore it is NOT travelling at the speed of causality just because it is light, no? Something that took the same journey and returned faster would not be breaking the speed of causality unless it returned before you turned on the source.

Tachyons are not ruled out by Relativity, but they have never been watched. They are also less useful than one might think, because these particles (if they exist) could never be slower than the speed of light. I suppose that would make them really hard to control.

Would seem according to this discussion that if all things I've been told are following the laws of physics as we believe them to be, then they'd simply be particles moving faster than the speed of light, though I would argue even faster than that, faster than the speed of causality itself, which some here are saying is impossible

That said, you're saying that tachyons have never been proven and are just theoretical? Are the theories regarding them based on how they might answer to observed phenomenon or are we talking about something that is purely imagined as a possibility?


I'm maintaining all of this with an open mind and trying to understand some of these concepts and just pointing out what doesn't seem to make sense about them to my limited degree of understanding.

 

[Playsoneasy]

Both steam and GOG versions are fine for mods.

I recommend the one from https://www.gog.com/game/sid_meiers_civilization_iv_the_complete_edition
It's a bit expensive there atm though.

If you get the steam version you will need to opt into the beta version of it to get the original firaxis release that work with C2C. (steam made a patch for it that breaks C2C ^^)

How has the steam version broke C2C? My C2C installation works fine with my Steam Civ 4. Has there been a new update?

 

[Toffer90]

How has the steam version broke C2C? My C2C installation works fine with my Steam Civ 4. Has there been a new update?

Steam patched BtS when the gamespy servers were shut down in 2014, they removed some main menu stuff related to multiplayer that actually still work fine, and they did something that makes a lot of UI icons disappear from existence in C2C.
E.g. religion icons in the scoreboard that show what state rel. each civ has are mssing, the great person icons in the GP bar, and a lot of icons in the pedia, probably more, I haven't cataloged all the missing icons on the latest steam version.
Steam deleted a lot of files in BtS they believed were junk files, like the dll source files, maybe C2C depend on one of them or something.

 

[Playsoneasy]

Steam patched BtS when the gamespy servers were shut down in 2014, they removed some main menu stuff related to multiplayer that actually still work fine, and they did something that makes a lot of UI icons disappear from existence in C2C.
E.g. religion icons in the scoreboard that show what state rel. each civ has are mssing, the great person icons in the GP bar, and a lot of icons in the pedia, probably more, I haven't cataloged all the missing icons on the latest steam version..

So what would you suggest? Dowload the beta version from steam, then reinstall C2C?

 

[Toffer90]

So what would you suggest? Dowload the beta version from steam, then reinstall C2C?

Just activate the beta version, don't have to reinstall C2C.

 

[Playsoneasy]

Just activate the beta version, don't have to reinstall C2C.

OK.

 

[tmv]

This COULD all make sense if we're talking about something that is obviously true based on observations on a truly intersolar magnitude that we'd somehow have to be able to map, which perhaps we think we have ways to do.

You can get away with testing over smaller distances as long as the precision is high enough.

Is it not possible to 'clock' how long it takes for the emergence of light to reach from emergence point A to receiving point B? If I shoot a laser at the moon and have it bounce back, it's taking actual time to return that can be measured (from the moment the laser is turned on to the moment it hits the point of return), therefore it is NOT travelling at the speed of causality just because it is light, no? Something that took the same journey and returned faster would not be breaking the speed of causality unless it returned before you turned on the source.

An answer to this can be found here: https://en.wikipedia.org/wiki/Tachyonic_antitelephone - the one-way example given there might not be that impressive (you can find a frame of reference where the superluminal movement leads to the arrival happening before the departure). But the two-way example shows a case where sending information into the past becomes possible if two people have access to such a device that can send information with superluminal speed. And that is true as long as the signalling speed is superluminal - that is why this is the speed of causality. Causes must happen before their effects.

That said, you're saying that tachyons have never been proven and are just theoretical? Are the theories regarding them based on how they might answer to observed phenomenon or are we talking about something that is purely imagined as a possibility?

They are not ruled out by theory. Put together with the fact that there is no evidence that supports their existence and certainly no observed phenomenon that requires their existence in order to be explained, there is usually a very strong assumption that they don't exist.

 

[Snofru1]

Why are executives (the guys that expand corporations) in the military unit category? They should be counted as civilians, even better would be missionaries so that they they can be more easily filtered out in the city view.

 

[Yudishtira]

In its frame of reference, the photon (call it A) that just got here from Alpha Centauri (or from just down the street) travelled at infinite speed. A photon from there going in the opposite direction was going at an infinite speed twice that of A.

Two objects travelling at (a very modest) 0.51c in opposite directions from the same start point are already exceeding the speed of light in each other's reference frame. And if I merely walk with my back to Alpha Centauri, I am moving at superluminal speed with respect to a photon leaving there in the opposite direction.

Superluminal travel is a central corollary of relativity, once you start talking about frames of reference (as you must) as well as time dilation (not required but it makes FTL even easier), travelling faster than c becomes trivial. Shall we move on?

 

[raxo2222]

In its frame of reference, the photon (call it A) that just got here from Alpha Centauri (or from just down the street) travelled at infinite speed. A photon from there going in the opposite direction was going at an infinite speed twice that of A.

Two objects travelling at (a very modest) 0.51c in opposite directions from the same start point are already exceeding the speed of light in each other's reference frame. And if I merely walk with my back to Alpha Centauri, I am moving at superluminal speed with respect to a photon leaving there in the opposite direction.

Superluminal travel is a central corollary of relativity, once you start talking about frames of reference (as you must) as well as time dilation (not required but it makes FTL even easier), travelling faster than c becomes trivial. Shall we move on?

0.5c + 0.5c is not 1c.
1km/s + 1km/s is 2 km/s.... unless you are precise enough.
https://en.wikipedia.org/wiki/Velocity-addition_formula