Two billion planets in our galaxy may be suitable for life

ShowMeTheCash

Zubeneschamali wrote: »

Firstly, it is you that has the dilation wrong, the twin who travels is younger, not older. Secondly, the whole point is that time does not synch up - less time happens for the moving end of the gate, the clock on it is not wrong, that is how much time has actually passed.

If I wave my hand once per minute, we know exactly what will happen, because we know how a clock is affected. I wave 15 times through the hole at A.

On board ship I wave 5 times on the outward journey, 5 times on the return and I still have 5 waves left when the ship lands, just as the clock still shows 5 minutes.

So now my hand exists twice - and we can hand it an apple, and that apple will travel into the past when the hand is pulled in - but it can't, because I already pulled out my hand with no apple 5 minutes before the apple was handed to me.

Paradox.

From the paper on closed timelike curves I linked to earlier "Most physicists react to this by asserting that the laws of physics must prevent the existence of classical, traversable wormholes". I'm with them.

OK I state in my example A which is moving on the spaceship perceives 5 mins of time.
B which is not moving perceives 10 minutes of time...
So no I am not wrong, you have just said exactly the same thing as I have!
A is younger by 5 mins!

But it your earlier example you meant someone is putting there arm through from B to A, in my example I am doing it from A to B...
But it does not matter!

Zubeneschamali wrote: »

Secondly, the whole point is that time does not synch up - less time happens for the moving end of the gate, the clock on it is not wrong, that is how much time has actually passed.

I am still not sure you really understand this...

Time is not a constant, its a measurement relative to something else.
Also time will sync, this is basic stuff!

The theory is this, we sit and talk you sound normal.
You begin to move, the faster you move you will sound very slow to me every word geeetttttssss looonnnggggeeeer, but to you, you are speaking normal.
When I speak, all you hear is very fast tweets like someone is fastforwarding a tape... As you slow down we move back into the same time SYNC!!

At no point in the above example will you hand exist twice!

On board you will have the full 15 times... there is no 5 more to go at the end...

The idea is that on the end time is moving slower the waves will appear slower to the viewer! Doing it the opposite way it would appear faster... They do not happen at the same rate!

Zubeneschamali

ShowMeTheCash wrote: »

OK I state in my example A which is moving on the spaceship perceives 5 mins of time.
B which is not moving perceives 10 minutes of time...
So no I am not wrong, you have just said exactly the same thing as I have!
A is younger by 5 mins!

OK, we've swapped our As and Bs. We agree that the travelling end is 5 minutes younger, good.

Now:

ShowMeTheCash wrote: »

The theory is this, we sit and talk you sound normal.
You begin to move, the faster you move you will sound very slow to me every word geeetttttssss looonnnggggeeeer, but to you, you are speaking normal.
When I speak, all you hear is very fast tweets like someone is fastforwarding a tape... As you slow down we move back into the same time SYNC!!

This is utterly, utterly wrong. After you have slowed down and stopped, come to a complete halt back where you started, you have not experienced the full 15 minutes, your clock reads 11:55 because you only experienced 10 minutes.

Before you even go near the wormhole example, you need to understand the twins example. This is not even a thought experiment anymore, it's been tested with real clocks. The clock that moves experiences less time, and it does not speed up, catch up or sync up when it comes back.

This is just ordinary Relativity from a hundred years ago.

Adding the wormhole gives you the paradox, because the different ends of the wormhole have experienced different amounts of time, and it becomes a time machine.

ShowMeTheCash

Zubeneschamali wrote: »

OK, we've swapped our As and Bs. We agree that the travelling end is 5 minutes younger, good.

Now:



This is utterly, utterly wrong. After you have slowed down and stopped, come to a complete halt back where you started, you have not experienced the full 15 minutes, your clock reads 11:55 because you only experienced 10 minutes.

Before you even go near the wormhole example, you need to understand the twins example. This is not even a thought experiment anymore, it's been tested with real clocks. The clock that moves experiences less time, and it does not speed up, catch up or sync up when it comes back.

This is just ordinary Relativity from a hundred years ago.

Adding the wormhole gives you the paradox, because the different ends of the wormhole have experienced different amounts of time, and it becomes a time machine.

OK, again you have not understood what I am talking about.

When I say back in Sync I mean we are now back moving through time at the same speed... While an object is moving it is experiencing time differently to an object that is static.

The basic math around this is to do with time and velocity.
If we travel at the same velocity then T will remain the same for the both of us.

If you travel with a greater V then you experience less of T, but only in comparison to something else.

So to go back to my example you moving you experience 5 mins I experience 10.
My watch reads 12:00, yours says 11:55...

When you stop moving we return to the same sync...

Now you could argue you travelled 5 mins into the future... But we are all travelling into the future, you just happened to percieve time slower due to your velocity difference relative to me.. So you had (T - V) = 5 mins relative to my 10 mins.

But at no point could you pull your arm through something or be able see your self do something...

What you are talking about is moving backward through time, I can assure you, you are incorrect in your thought process around this.

As I said before, if we could watch each other while you move.

You perceive time for 5 mins and I for 10mins.
You would apper very slow to me, infact everything you do or say would be happening at half the normal rate to me.
You on the other hand would be watching me, I would appear very fast, infact I would me moving and talking at twice the rate I would normally be...

Does this now make sense?

ShowMeTheCash

You wormhole example does not hold much weight...

Also your example is basic at best and did not make any real sense!

In the example you give the idea that you could land back and grab your own hand still does not hold true, you have no math to back that up.

Velocity has an impact on time but this whole travelling has confused you.

So let me try and simplify this example

Lets say we have a bubble, when you enter the bubble time will move slower for anyone in the bubble.

So essentially the same exmple:
You go in for 5 mins:
And come out.
I watched you in the bubble for 10 mins.

Now go back in for 5 but stick you hand out of the bubble.

What do you think happens when you get out of the bubble after 5 mins?

Are you going to get out and still see your hand sticking out of the bubble?

However, the wormhole paper is touching on time slicing...
The idea of Now is a weird concept, but I still do not think you really understand the above so I might touch on it later if we can agree on something here

ShowMeTheCash

Also the twins example...

You are not explaining yourself very well...

My example of you moving very slowly and me moving faster IS the twins example...
But you seem unable to visualise what actually happens I am doing my best to give a simplified example.

One twin heads of moving very fast comes back 10 years later. But his twin has aged 20 years or 30 years or 40.

They both experience time differently (T) due to velocity (V)...

The examples are the same

Zubeneschamali

ShowMeTheCash wrote: »

But at no point could you pull your arm through something

I agree, because faster-than-light communication and travel are impossible.

If faster-than-light travel or communication are possible, then so is time travel.

This is not just my opinion, it falls out of the physics, and if you are able to disprove it, you'll win a Nobel prize, since it probably involves quantum gravity.

Google "closed timelike curves" for lots more maths than you can follow on the subject.

ShowMeTheCash

Zubeneschamali wrote: »

I agree, because faster-than-light communication and travel are impossible.

If faster-than-light travel or communication are possible, then so is time travel.

This is not just my opinion, it falls out of the physics, and if you are able to disprove it, you'll win a Nobel prize, since it probably involves quantum gravity.

Google "closed timelike curves" for lots more maths than you can follow on the subject.

What are you talking about??

No one needs to travel faster than the speed of light!
You seem to be jumping all around in you ideas....

In my example no one is travelling faster than the speed of light!
In the Twins example no one is travelling faster than the speed of light...

You have dreamt up a paradox scenario which is simply incorrect!

You do not seem to understand that basics on Time and relativity but you want to try to explain wormhole and quantum gravity...

I suggest walking before running

Zubeneschamali

ShowMeTheCash wrote: »

What are you talking about??

For the past two days, I have been talking about this: the idea of going from point A to point B instantaneously

I have been making the point that this is time travel, and therefore impossible.

ShowMeTheCash

And I have said the idea is that you do not travel.

So why are you talking about light travel?

And you argument to why this is time travel makes no sense!

Frank Lee Midere

ShowMeTheCash wrote: »

Also the twins example...

You are not explaining yourself very well...

My example of you moving very slowly and me moving faster IS the twins example...
But you seem unable to visualise what actually happens I am doing my best to give a simplified example.

One twin heads of moving very fast comes back 10 years later. But his twin has aged 20 years or 30 years or 40.

They both experience time differently (T) due to velocity (V)...

The examples are the same

No because of acceleration. The twins paradox is a paradox because both twins are travelling at , or very near, the speed of light relative to each other so both should see time on the other as slowing down. The answer to the paradox involves acceleration.

Greenmachine

I came in here to find out about the martians. Instead I have a tangled web of bizarre thought processes.

Zubeneschamali

ShowMeTheCash wrote: »

And I have said the idea is that you do not travel.

It does not matter how you get from A to B, or whether you call it travel or not. If you get there faster than light can get there, it is time travel.

This is not at all controversial, I have linked to a bunch of papers and references laying out the physics.

If you only want to read one, read this one.

maninasia

Real physics is bizarre. Welcome to reality.

Actually there are many purported methods to 'time travel' or get around the speed of light barrier.

I tend to think of the speed of light barrier as a bit like a ship in the ocean, yes the ship has a limit to the speed it can travel through the water, but it doesn't matter because you can skip the ocean altogether and take a plane instead.

The plane in this case would be through bending space-time or represents multiverse theory of a bunch of other pretty weird stuff to us mortals.

It is actually possible to 'travel' or at least exist here or in the farthest reach of the universe at any given instant (for sub atomic particles), what the speed of light barrier says is not possible is that information cannot be transmitted faster than the speed of light.


We do have time travel happening all around us in terms of relativistic effects (and these effects are poorly understood by the public, but if we traveled at close to the speed of light and went to the nearest star and back, we'd have aged just a few years, but everybody we know would probably have died, that's time travel from my definition and bloody amazing), but the time travel of going back to our own past is something different again.

The last example of travelling to the nearest star and back is also very pertinent to the multitudes who think that space is vast and travel across it would take forever. It would take forever for the observer, but for the traveler it would not be a problem as long as they are travelling at close to the speed of light and happy to exist on their lonesome own. Your OWN time is the most important (everybody exists in their own universe ain't that right...).

This is a misunderstanding commonly held even among scientists! The only reason I believe this misunderstanding exists is simply due to technological limitations. It's a good example of how practical reality determines perception (remember galileo and the telescope, or the microscope and bacteria...I see the planets and the microbes..therefore they become more real and concrete to me).

What happens when we travel at the actual speed of light (if that was possible)? Space would shrink to zero and we would have arrived at the destination at the time that we left. Photons travel at the speed of light, so if one was a photon one would perceive the universe very differently than we would. The photon would simply exist everywhere at the same time to itself (as far as I can understand it).

It's always handy to think of space shrinking instead of time reducing. The faster you travel the more space shrinks! That's because there is not a single thing called space or a single time called time, but an entity which is called space-time.

ShowMeTheCash

Frank Lee Midere wrote: »

No because of acceleration. The twins paradox is a paradox because both twins are travelling at , or very near, the speed of light relative to each other so both should see time on the other as slowing down. The answer to the paradox involves acceleration.

Here is the example

http://en.wikipedia.org/wiki/Hafele–Keating_experiment

There was a lot of theorys and still are, time dialation however can be measured as part of the above experiement...

Initial acceleration of course is needed but it is more to do with the differing Velocity... Velocity explains the difference between two things.

ShowMeTheCash

Zubeneschamali wrote: »

It does not matter how you get from A to B, or whether you call it travel or not. If you get there faster than light can get there, it is time travel.

This is not at all controversial, I have linked to a bunch of papers and references laying out the physics.

If you only want to read one, read this one.

Ok me walking to the door is also time travel.

But I think what your trying to say is if I could teleport from A to B faster than it would take a beam of light to travel a distance I am travelling backwards in time? and could result in some kind of paradox scenario?

Wormhole theory is different, so is time sclicing.

There is a lot of other theorys and arguments you could make that would make some sense, what I am saying is, you have outlined a sceario whereyby there is no paradox and you are implying that this means you can traval back in time, I am simply stating you are wrong.

mickmackey1

maninasia wrote: »

We do have time travel happening all around us in terms of relativistic effects (and these effects are poorly understood by the public, but if we traveled at close to the speed of light and went to the nearest star and back, we'd have aged just a few years, but everybody we know would probably have died, that's time travel from my definition and bloody amazing), but the time travel of going back to our own past is something different again.

The last example of travelling to the nearest star and back is also very pertinent to the multitudes who think that space is vast and travel across it would take forever. It would take forever for the observer, but for the traveler it would not be a problem as long as they are travelling at close to the speed of light and happy to exist on their lonesome own. Your OWN time is the most important (everybody exists in their own universe ain't that right...).

What happens when we travel at the actual speed of light (if that was possible)? Space would shrink to zero and we would have arrived at the destination at the time that we left. It's always handy to think of space shrinking instead of time reducing. The faster you travel the more space shrinks! That's because there is not a single thing called space or a single time called time, but an entity which is called space-time.

Well explained, but what I don't get is the following: imagine you were small enough to jump on a photon of light and had been zipping across the universe since the beginning. Does that mean

a) the distance you would have travelled is zero, because distances contract as speed increases, and therefore the size of the universe, from the perspective of a photon of light, is actually... no size at all i.e zero?

b) if time stands still at the speed of light then photons are the same age they always were, so does it then make any sense to say that the age of the universe is 14 billion years but that the age of light is... zero??

Frank Lee Midere

ShowMeTheCash wrote: »

Here is the example

http://en.wikipedia.org/wiki/Hafele–Keating_experiment

There was a lot of theorys and still are, time dialation however can be measured as part of the above experiement...

Initial acceleration of course is needed but it is more to do with the differing Velocity... Velocity explains the difference between two things.

No. If the two moving objects are in different frames and both are travelling at different speeds both see the other as being time dilated. It's acceleration not velocity which caused that affect.

ShowMeTheCash

mickmackey1 wrote: »

Well explained, but what I don't get is the following: imagine you were small enough to jump on a photon of light and had been zipping across the universe since the beginning. Does that mean

a) the distance you would have travelled is zero, because distances contract as speed increases, and therefore the size of the universe, from the perspective of a photon of light, is actually... no size at all i.e zero?

b) if time stands still at the speed of light then photons are the same age they always were, so does it then make any sense to say that the age of the universe is 14 billion years but that the age of light is... zero??

It is not easy to get your head around this

But in theory yes zero to both a and b)

The idea is that the photon does not experience time at all, therefore not only is the time zero but it also implies the photon can exerience everywhere at once.

ShowMeTheCash

Frank Lee Midere wrote: »

No. If the two moving objects are in different frames and both are travelling at different speeds both see the other as being time dilated. It's acceleration not velocity which caused that affect.

From the article:

Considering the Hafele–Keating experiment in a frame of reference at rest with respect to the center of the earth, a clock aboard the plane moving eastward, in the direction of the Earth's rotation, had a greater velocity (resulting in a relative time loss) than one that remained on the ground, while a clock aboard the plane moving westward, against the Earth's rotation, had a lower velocity than one on the ground.

Acceleration suggests a continuous increase in speed.
This is incorrect, essentially we could stop the acceleration i.e.
A and B are moving at 0
B goes from 0 to 100 getting from 0 to 100 is the acceleration but we can stop at 100 and continue at 100 where we now see dialation but we are no longer accelerating..

Satelites see this all the time and why sat nav has special software to account for the dilation, but they are not accelerating they have a constant velocity in comparison to the earth.

Zubeneschamali

ShowMeTheCash wrote: »

And I have said the idea is that you do not travel.

So why are you talking about light travel?

You were at A. You are now at B. You did this faster than light can travel from A to B. It's travelling faster than light, no matter what you call it.

You didn't like my stargate example, so I'll try a different one. I invent a space-bending parcel technology. You put a letter in it, program a destination, and press a button. It bends space until it's at the destination, then unbends it. This takes a little time, but say it always gets there 2.4 times faster than light would.

To test it, we'll send a 2 way message. You fly off in a ship at 0.8c. (To you, it looks as if Earth is receding at 0.8c) After 300 minutes by your watch, you write "Blue" on a note, put it in the parcel, and send it to me.

150 minutes later on your clock, you can work out that the parcel travelled 2.4c*150 = 360 light minutes, and Earth is now 450*0.8c = 360 light minutes away, so I just got the parcel.

You can also work out what my clock reads when I get it: the dilation factor is the square root of 1 minus (0.8c over c) squared, which is the square root of 1 -.64, which is the square root of 0.36, which is 0.6.

So you know my clock reads 270 minutes when I get the parcel.

I write Do not send "Blue" on a note, put it in the parcel and send it back.

Do the sums again, and I find after another 135 minutes, the parcel is at a distance 135*2.4c= 324 light minutes, and your ship is at a distance (270+135)*0.8c = 324 light minutes. So you receive the parcel when my clock reads 405 minutes. Applying the time dilation formula again, I can work out that your clock reads 0.6x405= 243 minutes.

So 57 minutes before you send the message "Blue", you receive a message saying Do not send "Blue", so you send "Green" instead.

Paradox!

And again: note that it does not matter in the least how the parcel works, wormholes, bending space, teleportation, hyperspace: all that matters is that it gets from A to B faster than light can.

ShowMeTheCash

Zubeneschamali wrote: »

You were at A. You are now at B. You did this faster than light can travel from A to B. It's travelling faster than light, no matter what you call it.

You didn't like my stargate example, so I'll try a different one. I invent a space-bending parcel technology. You put a letter in it, program a destination, and press a button. It bends space until it's at the destination, then unbends it. This takes a little time, but say it always gets there 2.4 times faster than light would.

To test it, we'll send a 2 way message. You fly off in a ship at 0.8c. (To you, it looks as if Earth is receding at 0.8c) After 300 minutes by your watch, you write "Blue" on a note, put it in the parcel, and send it to me.

150 minutes later on your clock, you can work out that the parcel travelled 2.4c*150 = 360 light minutes, and Earth is now 450*0.8c = 360 light minutes away, so I just got the parcel.

You can also work out what my clock reads when I get it: the dilation factor is the square root of 1 minus (0.8c over c) squared, which is the square root of 1 -.64, which is the square root of 0.36, which is 0.6.

So you know my clock reads 270 minutes when I get the parcel.

I write Do not send "Blue" on a note, put it in the parcel and send it back.

Do the sums again, and I find after another 135 minutes, the parcel is at a distance 135*2.4c= 324 light minutes, and your ship is at a distance (270+135)*0.8c = 324 light minutes. So you receive the parcel when my clock reads 405 minutes. Applying the time dilation formula again, I can work out that your clock reads 0.6x405= 243 minutes.

So 57 minutes before you send the message "Blue", you receive a message saying Do not send "Blue", so you send "Green" instead.

Paradox!

And again: note that it does not matter in the least how the parcel works, wormholes, bending space, teleportation, hyperspace: all that matters is that it gets from A to B faster than light can.

You appear to have your diation in reverse.

I am traveling therefore time for me is moving slower, time for you is moving faster!!!

You seem to think that when you receive the parcel at 270 mins
If I sent it at 300 + the 150 it takes to get back total 450

The time you get the package at your time is 750 mins and not 270.

ShowMeTheCash

Why do you think time for the static object would be less than the object that is moving?

Your math is sound just have just applied it the wrong way about...

Zubeneschamali

ShowMeTheCash wrote: »

You appear to have your diation in reverse.

It's symmetrical: no-one is accelerating in this scenario.

maninasia

To go back to the supposed 'problem of travelling at less than the speed of light' there is a chapter in this book that explains why this is not a problem for the individual or community on a given spaceship. The time taken for acceleration and deceleration would probably occupy most of the flight. He did have a couple of minor errors in it though, supposedly with the clock calculation.


http://www.amazon.ca/Unconventional-Flying-Objects-Scientific-Analysis/dp/1571740279


Also it should be stated that every species concept of time is different (over generations and between species), and that in the near future intelligence should be immortal with no limit on replication i.e. you can clone intelligence infinitely and even transmit that at the speed of light from one place to another. There are even theories that at a certain level of intelligence and technology some civlisations may disappear 'up their own alien arse ' and hang out in virtual reality compared to the gritty reality of navigating through dirty space rocks.

What does time mean then?


Not only could you 'upload' or 'download' intelligence at the speed of light across a given galaxy, you could use entanglement to achieve quantum teleportation of a complete object or individual (the original would be destroyed in the process) but you would have had to entangle the particles first and then move the entangles partners to remote areas in advance, think of it is a a very expensive galactic priority Fedex!

ShowMeTheCash

I am not concerning myself with the problems of reaching the speed.
This is a hypothetical scenario and purely on the math and how relative time dilation works.

There are two things people have wrong.
1. The dilation happened only in the acceleration... This is incorrect.
Yes you need to accelerate to create the speed and velocity but you do not need to maintain and continued the acceleration.
In very simply terms, a guy flying round a race track at 200mph is essentially seeing some dilation to the guy in the stands watching him, the dilation will be so small it will be almost unmeasurable but it is happening...

2. The portal idea whilst travelling will not cause a portal into the past...
Well not with what zuben has suggested.... The math above is incorrect and there are two fundamental areas that are completely wrong.

But zuben I think is confusing a few different paradigms all of which has some weight... But the example given is not correct.

Zubeneschamali

Zubeneschamali wrote: »

I invent a space-bending parcel technology.

Just to complete this example, here's what happens if the parcel travels as fast as actually possible, exactly light speed:

This time, lets both fly in ships, away from each other at a combined 0.8 lightspeed. This handles any doubts you might have about one of us being "stationary" (although that doesn't affect the maths at all).

We fly away from each other in our ships at a combined 0.8c. After 300 minutes by your watch, you write "Blue" on a note, put it in the parcel, and send it to me, as before.

1200 minutes later on your clock, you can work out that the parcel travelled c*1200= 1200 light minutes, and I am now 1500*0.8c = 1200 light minutes away, so I just got the parcel.

You can also work out what my clock reads when I get it: the dilation factor is the square root of 1 minus (0.8c over c) squared, which is the square root of 1 -.64, which is the square root of 0.36, which is 0.6.

So you know my clock reads 720 minutes when I get the parcel.

I write Do not send "Blue" on a note, put it in the parcel and send it back.

Do the sums again, and I find after another 2880 minutes, the parcel is at a distance 2880c= 2880 light minutes, and your ship is at a distance (720+2880)*0.8c = 2880 light minutes. So you receive the parcel when my clock reads 3600 minutes. Applying the time dilation formula again, I can work out that your clock reads 0.6x1200= 2160 minutes.

So the return message arrives well after the sent message, no paradox.

Zubeneschamali

maninasia wrote: »

I tend to think of the speed of light barrier as a bit like a ship in the ocean, yes the ship has a limit to the speed it can travel through the water, but it doesn't matter because you can skip the ocean altogether and take a plane instead.

The plane in this case would be through bending space-time or represents multiverse theory of a bunch of other pretty weird stuff to us mortals.

No, as shown in my long calculations, any sort of FTL travel or communication is time travel.

if we traveled at close to the speed of light and went to the nearest star and back, we'd have aged just a few years

This is true, but the energy needed to accelerate any sort of passenger ship up to this near lightspeed would be very large - think "destroy the earth" quantities of energy.

You can read about relativistic rockets at this link,

which suggests a 1 way trip in something the size of an Apollo mission at 1g to Alpha Centauri would require 1.7 million kilos of fuel converted to energy. Evey kilo is about 20 megatons, so 1.7 million kilos is about 600,000 times the energy in the biggest H-Bomb ever tested.

and that's a one way trip. A two way trip would be maybe 25 million giant H-bombs worth.

mickmackey1

ShowMeTheCash wrote: »

It is not easy to get your head around this

But in theory yes zero to both a and b)

The idea is that the photon does not experience time at all, therefore not only is the time zero but it also implies the photon can exerience everywhere at once.

So because photons have no age and no size, they don't exist... but they do exist. Clearly some playful aliens are having a huge laugh at our expense :pac:

ShowMeTheCash

Zubeneschamali wrote: »

Just to complete this example, here's what happens if the parcel travels as fast as actually possible, exactly light speed:

This time, lets both fly in ships, away from each other at a combined 0.8 lightspeed. This handles any doubts you might have about one of us being "stationary" (although that doesn't affect the maths at all).

We fly away from each other in our ships at a combined 0.8c. After 300 minutes by your watch, you write "Blue" on a note, put it in the parcel, and send it to me, as before.

1200 minutes later on your clock, you can work out that the parcel travelled c*1200= 1200 light minutes, and I am now 1500*0.8c = 1200 light minutes away, so I just got the parcel.

You can also work out what my clock reads when I get it: the dilation factor is the square root of 1 minus (0.8c over c) squared, which is the square root of 1 -.64, which is the square root of 0.36, which is 0.6.

So you know my clock reads 720 minutes when I get the parcel.

I write Do not send "Blue" on a note, put it in the parcel and send it back.

Do the sums again, and I find after another 2880 minutes, the parcel is at a distance 2880c= 2880 light minutes, and your ship is at a distance (720+2880)*0.8c = 2880 light minutes. So you receive the parcel when my clock reads 3600 minutes. Applying the time dilation formula again, I can work out that your clock reads 0.6x1200= 2160 minutes.

So the return message arrives well after the sent message, no paradox.

So are we in agreement here, there is no paradox

Zubeneschamali

ShowMeTheCash wrote: »

So are we in agreement here, there is no paradox

Of course there is no paradox, because bending space to travel faster than light is impossible.