The Space Topic

[DistortAMG]

We aren't time travelling!
Relativity does not mean time travel, it is time distortion, a massive difference.
The Apollo travellers did not "time travel" anywhere, time was distorted through the velocity and distance travelled, there was no "travel jump" or "time jump", there was simply time distortion, caused by relativity.
That is not, and never will be, time travel.
I would like my moon ticket reservation with Pan Am cancelling, as we seem to be much further from scheduled services to the moon than we were fifty years ago.
Valid points, grounded in science, but still... regular interplanetary travel will not happen for humans in our lifetimes, and probably within human civilisation on the planet.

According to NASA, time travel is possible, just not in the way you might expect. Albert Einstein's theory of relativity says time and motion are relative to each other, and nothing can go faster than the speed of light, which is 186,000 miles per second. Time travel happens through what's called “time dilation.”

Two sides of the same coin. The Apollo astronauts did infact time travel. Into the future. It has been measured. They aged approximately 300 millenths of a second faster than the people on earth. These numbers are tiny yes, but the science is the same, valid and proven. But they key takeaway is, they aged faster than the people on the Earth, because they moved through time slightly quicker than the people on the earth. Which from the perspective of the people on the Earth is travelling through time.

A theoretical time machine would move time forwards, or backwards for the whole universe at the same time. That is not how time works. It's relative, not absoloute.

My phone is playing up. That top paragraph is a direct quote. It truly is fascinating stuff.

I totally agree. We will not see interplanetary travel in our lifetimes. But there are alot of things we will be able to do sooner than we think. Mainly due to quantum computers. Not because they are faster than regular computers (they are) but because the type of calculations they can tackle, are simply impossible with regular computer architecture that we have essentially used for all of the life of electronic computers.

 

[rob666]

They did not travel in time...they aged quicker because of relativity!!!
Massive difference.
If there has been such progress and growth in the industry, why have we not had a man on the moon since December 14th 1972?
Fifty years of exponential growth?
No.
The national governments involved couldn't afford to play the space race game anymore, so they stopped.

Now the vanity private spacemen have kicked in, blowing up rockets on a regular basis, burning dollar bills because they have nothing better to waste it on.

 

[DistortAMG]

Of course it is relativity. Time dilation and by extension, time travel, fall under the relativity bracket. Time is not an absoloute after all. Its relative. What you are saying is not wrong, but you are missing half the picture.

This is well documented online. Essentially, people on the ISS time travel too. Again, well documented. Truly fascinating stuff.

 

[rob666]

They don't.
They have lived their lives quicker, relative to us on earth, nothing else.
They have not "travelled in time" in any literal sense, their time has simply gone a tiny bit quicker than ours, relatively.
This was all well documented on my GCE A level Physics textbook, with a big chapter on the Apollo programme, forty years ago.
Relativity hasn't changed much in four decades.
I dropped physics.

 

[Matt N]

I took A Level Physics right to the end and got an A. We did a section on relativity as part of that course.

In spite of that, I have to say that until reading some of the recent posts in this topic, I thought of time travel as one of those pie-in-the-sky concepts invented to give the sci-fi movie genre some fun plots to work with. I never thought it was a genuinely plausible concept.

I was under the impression that relativity was simply time moving quicker in different parts of the universe? Surely that wouldn’t make time move any quicker on Earth?

From what I remember of Einstein’s Theory of Relativity, I agree with @rob666. Astronauts who go to space have simply lived their lives quicker rather than time travelled.

 

[shakey]

Isn't the Astronaut age thing the other way round ? They age slower not quicker ?

 

[rob666]

"astronauts on the ISS age more slowly, being 0.007 seconds behind for every six months."
Basically, huge masses of "stuff" generate gravity, and gravity distorts time fractionally.
Well done with that A Matt!
I gave up A level Maths and Physics after the taster weeks, made my eyes and ears hurt as much as my brain.
Some of the quantum physics stuff about quark, strangeness and charm still makes me giggle...like a Hawkwind fan.

Very small parts of the atoms of my coffee mug are also probably very tiny parts of the atoms of my living room carpet...all at the same time?!?
OK.

 

[Matt N]

"astronauts on the ISS age more slowly, being 0.007 seconds behind for every six months."
Basically, huge masses of "stuff" generate gravity, and gravity distorts time fractionally.
Well done with that A Matt!
I gave up A level Maths and Physics after the taster weeks, made my eyes and ears hurt as much as my brain.
Some of the quantum physics stuff about quark, strangeness and charm still makes me giggle...like a Hawkwind fan.

Very small parts of the atoms of my coffee mug are also probably very tiny parts of the atoms of my living room carpet...all at the same time?!?
OK.

Oh my, don’t start me on Particle Physics… there are so many strange terms where I’ve now forgotten what they mean, and I struggle to explain it without someone laughing at me!

On the subject of space, I don’t think commercial space flight is impossible by any means. Indeed, the likes of Virgin Galactic would suggest that it may quite likely be done at some stage.

 

[DistortAMG]

But. The key is they haven't aged faster relative to themselves, only relative to others. The time that would have passed relative to them, would be exactly the same as the time that would have passed relative to the people on Earth. Yet there is still that time difference / dialtion. It is not like time slows down for them, or if they were going fast enough, everything is in slow motion (or is it the other way round). Time would still pass as normal to them.

Even NASA call exactly what we are discussing as time travel. As in time dilation being an effect of time travel. See here.

If NASA call it time travel then that is good enough for me..

The key thing to remember is that while time will have appeared to have slowed down for one party. It has only slowed down relative to the perspective of the person watching. To the person who is apparently experiencing the time dilation, time seems to pass exactly as normal to them also. The dilation happens between the two parties, not specifically to either one. Then when they come back together, there is a difference in time. As the clock example explains. That is key to understanding this and that is why it is correctly referred to as time travel.

Put it another way, lets go hypothetical to try explain it better. Say that you spend your whole life on a space ship, doing the impossible speed of light through space. If it were possible to track you from Earth, your whole life on that spaceship will have appeared to have lasted a few days, while those on earth lived a life lasting 80 years. But to those on the space ship travelling at the speed of light, their life from their perspective also lasted 80 years in time. 80 years where a second passes in exactly the same time frame as it does on earth. Not 80 years where they felt 80 years sped right up and went really fast. That is only from a different position in space time....because of the time dilation being experienced. It is only when you bring the two parties back together, does the huge differences caused by time dilation that has happened between the parties and not specifically to either one, become blazingly apparent. The faster you travel, the bigger differences caused by time dilation, which in turn, is in effect travelling forward through time. That does not mean someone's clock is ticking slower or faster, not to the person who's clock it is. That is not how it works. It is a complex beast to explain. But I stand by what I said..

Everyone's clock ticks at exactly the same speed. Or going technical, the resonant frequencies of atoms from which we derive our most accurate time keeping from, resonate at the same frequency for everyone, thus, the passage of time is exactly the same for everyone. But there is that huge dilation, which can only mean one thing, which is one party has moved forward in time. If the clocks ticked at different rates like was suggested, then indeed that would bring the balance back from the dilation and there would be no time travel. But they do not tick at different speeds, they tick at the same speed which is the absolute key to all of this science.

Awesome discussion!!

 

[shakey]

So do people travelling extremely fast age quicker or slower relative to someone standing still ?

In the last few posts people have said both.

I am off to buy a flux capacitor !!

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[DistortAMG]

So do people travelling extremely fast age faster or slower relative to someone standing still ?

In the last few posts people have said both.

I am off to buy a flux capacitor !!

Sent from my Pixel 6 Pro using Tapatalk

They age faster. But only faster from the perspective of the person standing still and that is most important thing to take from all of this. From their own perspective, they would have aged at exactly the same rate, when measured by atomic levels of measurable time passage, or from a clock for you and I.

 

[shakey]

They age faster. But only faster from the perspective of the person standing still. From their own perspective, they would have aged at exactly the same rate, when measured by atomic levels of measurable time passage, or from a clock for you and I.

I thought I read it's the other way round, so if you travel at close to the speed of light then come back to earth, everyone else will have aged more than you.



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[DistortAMG]

I thought I read it's the other way round, so if you travel at close to the speed of light then come back to earth, everyone else will have aged more than you.



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You see, even I am getting confused now, it is very confusing believe me! Let me quote this from MIT's technology review, this will explain it far better than I ever could.

"Time dilation goes back to Einstein’s theory of special relativity, which teaches us that motion through space actually creates alterations in the flow of time. The faster you move through the three dimensions that define physical space, the more slowly you’re moving through the fourth dimension, time––at least relative to another object. Time is measured differently for the twin who moved through space and the twin who stayed on Earth. The clock in motion will tick more slowly than the clocks we’re watching on Earth. If you’re able to travel near the speed of light, the effects are much more pronounced.

Unlike the Twin Paradox, time dilation isn’t a thought experiment or a hypothetical concept––it’s real. The 1971 Hafele-Keating experiments proved as much, when two atomic clocks were flown on planes traveling in opposite directions. The relative motion actually had a measurable impact and created a time difference between the two clocks. This has also been confirmed in other physics experiments (e.g., fast-moving muon particles take longer to decay).

So in your question, an astronaut returning from a space journey at “relativistic speeds” (where the effects of relativity start to manifest—generally at least one-tenth the speed of light) would, upon return, be younger than same-age friends and family who stayed on Earth. Exactly how much younger depends on exactly how fast the spacecraft had been moving and accelerating, so it’s not something we can readily answer. But if you’re trying to reach an exoplanet 10 to 50 light-years away and still make it home before you yourself die of old age, you’d have to be moving at close to light speed."

The wording in the first paragraph is a little convoluted there, but when he says;

The clock in motion will tick more slowly than the clocks we’re watching on Earth

He is specifically referring to when you are watching the clock from earth, which he references earlier in the paragraph by saying;

the more slowly you’re moving through the fourth dimension, time––at least relative to another object.

The first paragraph basically takes the assumption you are watching from earth.

Time has travelled the same for all parties from the perspective of their own party, but, one party has clearly travelled at a different rate of time than the others, because when they come back to earth, they are different ages. While this specific article doesn't use the words time travel per say, (many do) when you travel through time at a different rate relative than others, you have time travelled.

If you came back to earth and you were younger than everyone else because time had physically slowed down for you, like was suggested. You wouldn't have time travelled. That slowing down of time for the person moving, would be the way everything stays in synchronisation within space time. Because that would mean the slowing of time for you would make many of your seconds on the spaceship, equal to a single earth second. The amount of seconds that would make up an earth second, would match up exactly and correctly to the proportions that you are younger, compared to the people on earth. Which is in no way time travel.

But as I mentioned earlier and as articles posted explain, it doesn't work like that. Time ticks the same for everyone. Time dilation happens between the two parties and not to the actual parties themselves, it doesn't just work like that, it could never work like that, it goes fundamentally about how space time works. Therefor, the only way the universe can synchronise the dilation in time back up, that was caused by the relative differences in movement, is the jump in time relative to one another. Aka time travel.

I totally get the argument being put forward, but there is a fundamental mis understanding in the assumption that the passage of time slows down from one party compared to another. It does not. The passage of time stays the same for both party's, it is just the dilation between the two parties, that gives the appearance that is has slowed down for the other party. This is extremely important, because if time did not stay the same, travel through it would be impossible. Yet it is not. Think of it like the doppler effect, it almost is, when an object like an ambulance has passed you by. You hear the sound being generated in a lower pitch, as the object generating the sound moves away from you. Not because the object generating the sound has actually lowered the pitch of the audio, but because the sound has dilated in between the objects, as the space between the two objects grows. Yet to you stood still, it seems like the ambulance has lowered the pitch of the siren. They do not work in exactly the same way, but very very similar. Enough to use them as an example here. As time doesn't work in the same way as it would with the doppler effect when sound is coming towards you. Change the sound waves being stretched out / dilated for space time and you are in a similar ball park.

Hopefully that makes sense.....I need a strong drink after thinking all that over in my head . Sorry if I am going off on one. I could talk about this for hours. Truly fascinating stuff. But also, truly confusing stuff. Some of the most confusing stuff known to man I would argue.

 

[rob666]

Shakey, the basic rule is, the further you are from a very large mass, (the Earth), the slower you age...very very marginally.
The NASA link states that we all travel in time, all the time.
That does not confirm "time travel"...I sit in a bus,,,I'm travelling in time...not what you are suggesting, but travelling in time all the same.
The clock stays the same because I am on the earths surface, whatever the speed and velocity.
Time distortion only starts away from the planet, but it is not time travel, simply distortion of the measure.
Throw a clock in a black hole...
It appears to stop ticking as it enters the event horizon...
That still isn't time travel, it is time distortion.
All the scientists agree it happens, but nobody has taken the full test, so we really don't know.
We are nowhere near achieving what is commonly known as time travel, science fiction for the next millennia or so.
By which time humans will not be trying to run the planet for the benefit of a single species.

 

[shakey]

They age faster. But only faster from the perspective of the person standing still and that is most important thing to take from all of this. From their own perspective, they would have aged at exactly the same rate, when measured by atomic levels of measurable time passage, or from a clock for you and I.

So according to a few articles I have just read on the tinterweb, an astronaut travelling very fast through space and then returning to earth would arrive home at a later date than the date shown on the astronauts watch. So effectively they will have travelled forward through time (as in earths relative time) and aged less than the people on earth.

It is also worth mentioning that despite this forward time travel, Valhalla would still be in technical rehearsals and people would still be banging on about brexit !!

Shakey, the basic rule is, the further you are from a very large mass, (the Earth), the slower you age...very very marginally.

Not heard that one before, but does that mean I am aging slower because I am no longer near my ex-wife ?

 

[James]

If you want to see time dilation in (fictional) action, watch Interstellar. It's a brilliant film and based on real science, it applies a lot of the theories/discussion over the last page of this thread.

 

[Matt N]

Funnily enough, I’ve actually seen Interstellar. We were shown it by our Physics teacher at A Level.

I remember finding it quite confusing… to be honest, I find the whole discussion of relativity and time dilation possibly one of the most confusing bits of Physics.

 

[rob666]

But I now want to hear your detailed explanation of the six types of quarks Matt, and precisely why it matters!
Prefer a bit of strangeness myself, obviously.

So according to a few articles I have just read on the tinterweb, an astronaut travelling very fast through space and then returning to earth would arrive home at a later date than the date shown on the astronauts watch. So effectively they will have travelled forward through time (as in earths relative time) and aged less than the people on earth.

It is also worth mentioning that despite this forward time travel, Valhalla would still be in technical rehearsals and people would still be banging on about brexit !!




Not heard that one before, but does that mean I am aging slower because I am no longer near my ex-wife ?

You may be ageing slower shakey, but sadly, as a male divorcee, you are now on a statistically quicker road to death.
And it is still your round.
Edit...double post, whip me in zero gravity, on the edge of the black hole, forever, with a stopped clock.
Possibly.

 

[shakey]

You may be ageing slower shakey, but sadly, as a male divorcee, you are now on a statistically quicker road to death.
And it is still your round.
Edit...double post, whip me in zero gravity, on the edge of the black hole, forever, with a stopped clock.
Possibly.

10:30 at yours on Thursday depending on how close I get to the speed of light of course.

For anyone else that happens to be flying by Blackpool Pleasure Beach on Thursday, we will at some point be creating maximum time dilation in the bar at the end of the universe, otherwise known as Crevettes.

 

[rob666]

...and everybody, the two boys from Yorkshire have to get the beers in first, and second...
and I'm not driving...
Special friend shakey...