Two billion planets in our galaxy may be suitable for life

ThunderCat

New data from Kepler indicates that planets capable of supporting life are far more common than previously thought...

http://www.theguardian.com/science/2013/nov/04/planets-galaxy-life-kepler

antofitz

awesome

mr lee

finding life on another planet is the ultimate goal for mankind and i suppose it works the other way aswell,other life finding us,either way it will be deeply profound,i hope i'l be alive to witness it,the aliens better hurry up.

maninasia

ThunderCat wrote: »

New data from Kepler indicates that planets capable of supporting life are far more common than previously thought...

http://www.theguardian.com/science/2013/nov/04/planets-galaxy-life-kepler

Than previously thought by who?

If there is life out there, it is far more likely to have evolved on rocky planets with liquid water on their surfaces, similar to Earth.

Rightttttt.. that would be from our massive example of..... one.

So using a low ball figure there are at least 100 billion in the Milky Way alone. And we don't know yet if there is life on the other planets in the Solar System or on our moons (which outnumber planets by 20:1).

Using our example of 1/100 billion we know that life is FAR MORE LIKELY TO HAVE EVOLVED ON LIQUID WATER ON A ROCKY PLANET SIMILAR TO EARTH.


But this eejit can make a statement like this and get so many thanks.

I give up.

(by the way the term for this is confirmation bias).

ThunderCat

maninasia wrote: »

Than previously thought by who?



Rightttttt.. that would be from our massive example of..... one.

So using a low ball figure there are at least 100 billion in the Milky Way alone. And we don't know yet if there is life on the other planets in the Solar System or on our moons (which outnumber planets by 20:1).

Using our example of 1/100 billion we know that life is FAR MORE LIKELY TO HAVE EVOLVED ON LIQUID WATER ON A ROCKY PLANET SIMILAR TO EARTH.


But this eejit can make a statement like this and get so many thanks.

I give up.

(by the way the term for this is confirmation bias).

The text I posted in the original post is just the title of the article and taken from the very start of the article itself. I only typed it out so it would give some context as to what the link was about. I saw it, thought it was relevant to this forum and thought that some people might like to read it.

maninasia

I'm not criticizing you, I'm criticizing the author of the article. But I would recommend people to look beyond a title and analyse things a bit more logically for themselves.

jumpjack

Crowdy.
Corwdier.
Scary.
More scary.

ShowMeTheCash

Life on any plannet will have a finite window, studys show that they reckon life began in around 3.5 billion years ago, the earth was around a billion years old when it did.

At some point the earth will go back to being a ball whereby life will not be able to survive... Solar flare... Suns tranformation into a red giant or something else...

Our time in the universe will probably be so insignificant an entire universe of life, people civilisations will never even know we where even here!!

But may... just maybe a civilisation at the same maturity maybe close enough for us or them to perhaps acknowledge either one of us actually existed...

I often amuse myself with technology.. Wondering what the greatest technological advancement in the universe ever was and when? Maybe it was life!

Rhys Essien

ShowMeTheCash wrote: »

Life on any plannet will have a finite window, studys show that they reckon life began in around 3.5 billion years ago, the earth was around a billion years old when it did.

At some point the earth will go back to being a ball whereby life will not be able to survive... Solar flare... Suns tranformation into a red giant or something else...

Our time in the universe will probably be so insignificant an entire universe of life, people civilisations will never even know we where even here!!

But may... just maybe a civilisation at the same maturity maybe close enough for us or them to perhaps acknowledge either one of us actually existed...

I often amuse myself with technology.. Wondering what the greatest technological advancement in the universe ever was and when? Maybe it was life!

I don't think technology had anything to do with how life began.:D

ShowMeTheCash

Depends what you deem as technology.

tac foley

Unless we can come up with a method of transporting our physical bodies many times faster than the speed of light, we are totally screwed, and we will never, ever, know.

More to the point, just think of the expense!

tac

Maudi

tac foley wrote: »

Unless we can come up with a method of transporting our physical bodies many times faster than the speed of light, we are totally screwed, and we will never, ever, know.

More to the point, just think of the expense!

tac

Hi tac..the speed of light as a restrainer is getting a bit old fashioned..i feel the speed of light as a limitation will be proven to be wrong (in the future : )

Maudi

tac foley wrote: »

Unless we can come up with a method of transporting our physical bodies many times faster than the speed of light, we are totally screwed, and we will never, ever, know.

More to the point, just think of the expense!

tac

Hi tac..the speed of light as a restrainer is getting a bit old fashioned..i feel the speed of light as a limitation will be proven to be wrong (in the future : )

Manach

My own take on life, is that the development of such was both fraught with risk and catastrophe during its evolution on earth - which did act as a driver out could have wiped all life out so then advanced life even with the numerous planets mentioned would be quite rare.
On expense, as per Tac, get the India Space agency to do so. They have run successful missions for only about $80M

BorneTobyWilde

http://www.youtube.com/watch?v=suBp3ai-xG8
http://www.youtube.com/watch?v=3vYjRt7Sizc

They showed up a day ago in Germany. They do exist

maninasia

tac foley wrote: »

Unless we can come up with a method of transporting our physical bodies many times faster than the speed of light, we are totally screwed, and we will never, ever, know.

More to the point, just think of the expense!

tac

The brain is simply a neural network. A neural network can be consrtucted out of many different types of materials. It can even bounce around from place to place. As such, there is no limitation in beaming our brain (neural network) around in the future.

You might need something to beam it to, you can simply send that ahead.

maninasia

Maudi wrote: »

Hi tac..the speed of light as a restrainer is getting a bit old fashioned..i feel the speed of light as a limitation will be proven to be wrong (in the future : )

There is no evidence that the speed of light can be superseded so far. None.

However once you can bend space the speed of light may become immaterial.

As I always say, after they invented planes people hardly ever take a boat across the Atlantic ocean. It doesn't matter that there is a finite speed limit for boats on water.

Zubeneschamali

maninasia wrote: »

However once you can bend space the speed of light may become immaterial.

Bending space does not get you around the problems of faster than light travel. It's still time travel, unless relativity is wrong.

maninasia

This sentence doesn't mean anything to me, can you explain more?

Zubeneschamali

maninasia wrote: »

This sentence doesn't mean anything to me, can you explain more?

According to relativity, travelling from A to B faster than light travels from A to B is time travel, meaning you could kill your own grandfather and disappear in a puff of logic.

Anything which allows this kind of causality violation is impossible.

ShowMeTheCash

Zubeneschamali wrote: »

According to relativity, travelling from A to B faster than light travels from A to B is time travel, meaning you could kill your own grandfather and disappear in a puff of logic.

Anything which allows this kind of causality violation is impossible.

I think you are wrong in this description, it does not appear to make sense!
Granted time is a tricky one.

But what your saying here is not correct...

The idea of bending space is the idea of not having to make the journey.

It take light something like 8 minues to travel from the sun to here.
Bending space is the idea of the Now, you are not traveling through time, actually you are not traveling it all, the idea of going from point A to point B instantaneously...

Zubeneschamali

ShowMeTheCash wrote: »

The idea of bending space is the idea of not having to make the journey.

The point is that it doesn't matter if you travel from A to B by warping space, wormholes, hyperspace, subspace or teleportation:

If you can get there or send a message faster than light can get there, you can set up a time-travel paradox.

Wikipedia mentions this problem for the Alcubierre warp drive, and gives references, and for wormholes, too.

Zubeneschamali

To spell out the problem using wormholes:

Say you've got a wormhole between two giant Egyptian rings, call them Stargates A and B, and you hang a clock on each. You take A on a spaceship and zoom it to Alpha Centauri and back, and then stand them beside each other. Just like the Twins in the Twins Paradox, the A clock shows an earlier time than the B clock. Let's say your ship wasn't very fast (for a starship), and you only managed 5 minutes total time dilation. The A clock reads 11:55, and the B clock 12:00.

Now step through the A gate: you pop out the B gate at 11:55, and tell yourself not to go through.

Paradox! It's 12:01 and there are two of you now! But the "now" you never went through so where did the "then" you come from? How about mass-energy conservation? 80kg of matter just came from nowhere!

This really is how the physics says wormholes would behave, if they were possible.

So they aren't possible.

ShowMeTheCash

Zubeneschamali wrote: »

To spell out the problem using wormholes:

Say you've got a wormhole between two giant Egyptian rings, call them Stargates A and B, and you hang a clock on each. You take A on a spaceship and zoom it to Alpha Centauri and back, and then stand them beside each other. Just like the Twins in the Twins Paradox, the A clock shows an earlier time than the B clock. Let's say your ship wasn't very fast (for a starship), and you only managed 5 minutes total time dilation. The A clock reads 11:55, and the B clock 12:00.

Now step through the A gate: you pop out the B gate at 11:55, and tell yourself not to go through.

Paradox! It's 12:01 and there are two of you now! But the "now" you never went through so where did the "then" you come from? How about mass-energy conservation? 80kg of matter just came from nowhere!

This really is how the physics says wormholes would behave, if they were possible.

So they aren't possible.

Look I think you have misinterpreted a few things.

Also your example does not make any sense!

Time dialation happens due Time dilution when an object is moving!
The perceived time to the object seems less to that of the observer.

When you get back if A reads 11:55 and B 12:00 you will not come out of B at 11:55, the dialtion has already happened you simply need to adjust your clock!

What you are talking about is time slicing, your example does not make sense but I understand what you are trying to say. (Time gets funny when we move)

Let say we had a magic telephone and I could call someone at the other end of the galaxy instantaneously, if both people remain static then the time slice should remain the same, if I start to say run in the opposite direction the time slice can move, so essentially I could call someone in the past, this is because the Now time frame can move if we do....

But this has nothing to do with what we are talking about...

The difficutly with the now is... there is no such thing, everything is moving when we say now we mean now relative to something else... But that is a very different to what we are talking about.

There is no paradox in your example nor should there be whereby we move by bending space to somewhere on the same time slice. i.e. Not moving in relation to the space we are moving too.

Zubeneschamali

ShowMeTheCash wrote: »

When you get back if A reads 11:55 and B 12:00 you will not come out of B at 11:55, the dialtion has already happened you simply need to adjust your clock!

No, it's not just a matter of your clock being wrong any more, because of the wormhole.

Repeat the experiment above, but this time you stand beside hole B, stick your hand through the hole and shake hands with the pilot throughout the trip.

Now, when he comes back with his time dilated end of the hole, you pull your hand out at 12:00, but for the hand sticking out his gate, it's still only 11:55, so you can chop that hand off! Or grab it and pull your 11:55 self though into 12:00. It's a closed timelike curve.

Still don't believe me? Have a read of this.

ShowMeTheCash

Zubeneschamali wrote: »

No, it's not just a matter of your clock being wrong any more, because of the wormhole.

Repeat the experiment above, but this time you stand beside hole B, stick your hand through the hole and shake hands with the pilot throughout the trip.

Now, when he comes back with his time dilated end of the hole, you pull your hand out at 12:00, but for the hand sticking out his gate, it's still only 11:55, so you can chop that hand off! Or grab it and pull your 11:55 self though into 12:00. It's a closed timelike curve.

Still don't believe me? Have a read of this.

No I understand the theory I just don't think you quite grasp it.
At no point will you land back and the hand will be sticking out...
Also you have your dilation the wrong way around... Not that it actually matters..

The time dialation only happens while you move not when you have stopped, when you stop you are essentailly back in sync.

But I will go with you on the example:

A and B, I put my hand in A and see it come out from B and wave for 3 seconds.
I now Jump in my spaceship with A at 11:50, put my hand threw and begin waving, I zip to Alpha Centauri and back and land back at A 11:55 and B 12:00...

What do you think has happened?
Why do you think there is a paradox?

let say we have an instantainious live feed from the space graft moving.
And the space craft has a live feed back to mission control...

The guys on the ground will have watched 10 mins of footage.
On the spacecraft you will have 5 mins of footage.

Let me explain what will happen.

Lets say on the journey I wave from side to side 60 times a min.
5 Mins x 60 = 300

How many times you reckon my hand will move from side to side in the 10 mins at point B?

It will still have only moved 300 times...
The dialtion should be visible the faster you move... Effectivly if you are able to see your hand and you move fast enough you may even see it begin to change! as time is effecting it differently than the rest of your body...

But as you slow down and you sync back up then you are back in sync... Albeit you hand is now 5 mins older than the rest of your body!

ShowMeTheCash

Your example and that paper has more to do with wormholes than the example we are talking about...

Wormholes become theoretical...

We usually have bands of how things work.
Newtons laws of physics work... within a band, but when we start looking at sub atomic particles then these laws of physics no longer work!

Same goes for wormholes theory as it makes a lot of assumptions about what a wormhole actually is.

zl1whqvjs75cdy

My head hurts. Are we going to have ET for real or not?

Zubeneschamali

ShowMeTheCash wrote: »

But as you slow down and you sync back up then you are back in sync... Albeit you hand is now 5 mins older than the rest of your body!

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.

Zubeneschamali

ShowMeTheCash wrote: »

Your example and that paper has more to do with wormholes than the example we are talking about...

No. The same logic applies to any method of faster-than-light travel or communication. It's time travel.

Zubeneschamali

donkeyoaty0099 wrote: »

Are we going to have ET for real or not?

Extraterrestrial life? Definitely.

Intellligent? Probably.

Contact it? Possibly.

Travel to meet it, or have it travel here to meet us? Unlikely.

Faster than light? Definitely not.

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.