Physics Spacetime - How does it work?

[Total Power]

Just reading about the concept of time dilation. It states that time actually slows down in space when in front of massive objects like the sun for instance. If someone orbits a black hole, just at the right distance so that you dont get sucked in, the force of gravity will be so strong that time slows down considerably.

the question is how does time slow down and is time literally woven into the fabric of space?

 

[swiftdog]

Can't help but think of that scene in Interstellar. As for how it works, no idea.

 

[Loonerty]

Just reading about the concept of time dilation. It states that time actually slows down in space when in front of massive objects like the sun for instance. If someone orbits a black hole, just at the right distance so that you dont get sucked in, the force of gravity will be so strong that time slows down considerably.

the question is how does time slow down and is time literally woven into the fabric of space?

It's because the laws of physics hold in every reference frame, with one constant across them: the speed of light.

In order for the speed of light to be held constant in the reference frame of a person travelling at very fast speeds, time dilation must occur (along with length contraction).

Same deal when close to massive objects like black holes, but it's much more complicated.

 

[Total Power]

It's because the laws of physics hold in every reference frame, with one constant across them: the speed of light.

In order for the speed of light to be held constant in the reference frame of a person travelling at very fast speeds, time dilation must occur (along with length contraction).

Same deal when close to massive objects like black holes, but it's much more complicated.

does the gravity of the black hole warp space so much that the space itself stretches causing us to experience time differently?

i have read that einstein has proved that all matter is energy, he also states that the faster an object moves, the more energy/mass it gains.
so if we combine these two facts, this means that we can time travel into the future by simply moving at extremely high speeds, right?
it kinda makes sense to me because if the mass of a black whole can distort time, then an object moving fast enough to equal the energy of the black whole would induce the same effect right? from my perspective, if every thing is energy, and mass gains energy the faster it moves, then i think its safe to assume that a object can move fast enough to make its energy equal to a larger mass/energy, right?

I dont know, its just something i am trying to get my head around

 

[Loonerty]

does the gravity of the black hole warp space so much that the space itself stretches causing us to experience time differently?

I guess that's a way to put it, yeah. Been a couple of years since I did the subject on it and it wasn't as easy to explain as special relativity.

i have read that einstein has proved that all matter is energy, he also states that the faster an object moves, the more energy/mass it gains.
so if we combine these two facts, this means that we can time travel into the future by simply moving at extremely high speeds, right?
it kinda makes sense to me because if the mass of a black whole can distort time, then an object moving fast enough to equal the energy of the black whole would induce the same effect right? from my perspective, if every thing is energy, and mass gains energy the faster it moves, then i think its safe to assume that a object can move fast enough to make its energy equal to a larger mass/energy, right?

Dunno about travelling into the future. I mean, if you travelled near the speed of light then (just like in Interstellar), you could age maybe a few years while hundreds have passed on Earth or something. The big caveat here is that you can never travel at or above the speed of light. Time, mass and length will change infinitely before you could travel the speed of light. It just can't happen.

 

[iluvparis]

Does that mean that time is just an artificial construct used to balance the fact that the speed of light is a constant?

 

[Total Power]

I guess that's a way to put it, yeah. Been a couple of years since I did the subject on it and it wasn't as easy to explain as special relativity.

Dunno about travelling into the future. I mean, if you travelled near the speed of light then (just like in Interstellar), you could age maybe a few years while hundreds have passed on Earth or something. The big caveat here is that you can never travel at or above the speed of light. Time, mass and length will change infinitely before you could travel the speed of light. It just can't happen.

Understood. how much mass do you think it would take to build a giant ball in space with enough mass to distort space to a point where time slows to a crawl, thus giving us a giant time machine near our planet lol.

also, isnt there a way we can artificially induce the effects of gravity on the space around it?
i mean, gravity is something that is natural, so humans should be able to recreate it under test conditions, if we can achieve this, we could in theory distort space to a point where time is extremely slowed so we can time travel to the future,,,in a way.

Just a thought.

 

[Loonerty]

Understood. how much mass do you think it would take to build a giant ball in space with enough mass to distort space to a point where time slows to a crawl, thus giving us a giant time machine near our planet lol.

Way more than we would be able to do lol. Probably more likely of travelling 0.9999999999999999999999c than doing that (which is still incredibly unlikely).

also, isnt there a way we can artificially induce the effects of gravity on the space around it?
i mean, gravity is something that is natural, so humans should be able to recreate it under test conditions, if we can achieve this, we could in theory distort space to a point where time is extremely slowed so we can time travel to the future,,,in a way.

Hmm I don't know what you mean by artificially inducing gravity. Gravity can be "artificially" induced by using rotation I guess. Have you seen The Martian? The large ship in that film simulates gravity by having a rotating cabin, which uses centripetal force to push the people on it to the outside.

 

[Taylor]

Depending on the point of observation:

Inside the gravity well - you will fly in and fly out as though nothing different has happened but when you leave your clock will be behind.

Outside the gravity well - you will fly in and stay there

If you think of space like an elastic band, you stretch it out a bit (the big bang started stretching it out already) and mark even intervals along it (we will call them one spacial unit) then a gravity well will draw that elastic band back on itself so it isn't stretched out anymore - the spacial units will appear closer together.

If you are traveling along at 1 spacial unit per second then you don't notice anything, you still pass one every second but to the person observing your travel outside the gravity well you are slowed way down because from their perspective one of your spacial units is 100000x smaller than their own and you are both traveling at one spacial unit per second.

 

[Long Live HFC]

so if we combine these two facts, this means that we can time travel into the future by simply moving at extremely high speeds, right?

Correct (though as others have noted travelling at the speed of light is not possible).

This experiment might interest you.

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

I dont know, its just something i am trying to get my head around

mate, i've been fascinated by time dilation for almost 30 years, and i still don't ******* get it

 

[FallingLiefs]

Understood. how much mass do you think it would take to build a giant ball in space with enough mass to distort space to a point where time slows to a crawl, thus giving us a giant time machine near our planet lol.

also, isnt there a way we can artificially induce the effects of gravity on the space around it?
i mean, gravity is something that is natural, so humans should be able to recreate it under test conditions, if we can achieve this, we could in theory distort space to a point where time is extremely slowed so we can time travel to the future,,,in a way.

Just a thought.

black holes will do it and just as a comparison they estimate the density of a black hole to be 1 earth to a golf ball. as already stated traveling at speed close to that of c is more likely the most efficient way of traveling to the future.

 

[Chrizzt]

Understood. how much mass do you think it would take to build a giant ball in space with enough mass to distort space to a point where time slows to a crawl, thus giving us a giant time machine near our planet lol.

The time dilation is all relative as to where you would be in the gravitational field. In the case of having such a large mass the gravitational effect of the large mass would mess up planetary orbits and cause them to be sucked into and collide with the larger mass.

Even if that wasn't a factor all life on Earth would experience effectively the same time dilation so it's not like we'd notice any difference anyway. Outside of our "gravitational bubble" the time scale would be the same as before.

also, isnt there a way we can artificially induce the effects of gravity on the space around it?
i mean, gravity is something that is natural, so humans should be able to recreate it under test conditions, if we can achieve this, we could in theory distort space to a point where time is extremely slowed so we can time travel to the future,,,in a way.

Just a thought.

"gravity is something that is natural" is a funny statement as it's not something we fully understand. What most people think of as "gravity" is the simple effect we see of attraction between massive (read: bodies with mass, not necessarily "huge") bodies. However the mechanisms of how this is manifest is still unclear. Whereas Newton described it as some force acting between bodies, Einstein later described it as the effect of energy warping space-time. The latter can be visualised by holding a bed sheet (symbolising space-time) parallel to the ground, and placing a sphere (e.g. basketball, symbolising mass) in the middle and watching the sheet curve under the sphere. We can't create mass/energy so in that sense we can't "create" the effect of gravity in such a way.

As described by Loonerty we can simulate the effects of gravity with the use of a centrifuge - however this has the obvious limitation of requiring a spinning platform. Given that our bodies are made to exist in a very narrow range of forces due to gravity, the problem of "controlling" gravity is a big one for space travel as anything more than short term occupation of planets could be highly detrimental or even fatal to humans due to the difference in gravity.

black holes will do it and just as a comparison they estimate the density of a black hole to be 1 earth to a golf ball. as already stated traveling at speed close to that of c is more likely the most efficient way of traveling to the future.

Travelling to the future via approaching the speed of light is a bit of a misleading concept. It's not as if you could jump forward in time then come back to the past. It would be more as if you removed yourself from the universe for X amount of time, then suddenly popped into existence but would have no way possible of "returning" to the past. In this way it would essentially be the same as being cryogenically frozen for X amount of time.

 

[Pie eyed]

I guess that's a way to put it, yeah. Been a couple of years since I did the subject on it and it wasn't as easy to explain as special relativity.

Dunno about travelling into the future. I mean, if you travelled near the speed of light then (just like in Interstellar), you could age maybe a few years while hundreds have passed on Earth or something. The big caveat here is that you can never travel at or above the speed of light. Time, mass and length will change infinitely before you could travel the speed of light. It just can't happen.

As long as you're moving you're travelling into the future.
If you are completely at rest time does not pass, but you have to take into account that everything in the universe is always moving and that you are within that constant flux.
Going into the past is impossible as you cannot move backwards in exactly the same path you moved forward, given the above.
All movement is to somewhere you have never been in the universe, relative to the rest of it.
Even though you take the same route home everyday, you always arrive a totally different destination relevant to he rest of the universe.

 

[Loonerty]

As long as you're moving you're travelling into the future.
If you are completely at rest time does not pass, but you have to take into account that everything in the universe is always moving and that you are within that constant flux.
Going into the past is impossible as you cannot move backwards in exactly the same path you moved forward, given the above.
All movement is to somewhere you have never been in the universe, relative to the rest of it.
Even though you take the same route home everyday, you always arrive a totally different destination relevant to he rest of the universe.

I took him to mean instantaneous time travel with the potential of returning.

 

[Total Power]

I wonder how this will change physics?

http://www.independent.co.uk/news/s...agueijo-imperial-college-london-a7443136.html

 

[Chrizzt]

I wonder how this will change physics?

http://www.independent.co.uk/news/s...agueijo-imperial-college-london-a7443136.html

Could be related to the idea of Process Physics - which claims that the original Michelson-Morley experiment actually proved that the speed of light was different in different directions rather than the now accepted version that it was a null result.

 

[Pie eyed]

You know you can slow light, even actually stop light.

 

[sataris]

You know you can slow light, even actually stop light.

There was some experiment where they slowed light down to 60mph (I believe by passing it through a block sodium),you could overtake it in your car lol

 

[Chrizzt]

You know you can slow light, even actually stop light.

I should have clarified, *speed of light in vacuum

 

[footyfan1978]

Essentially just means time and space are always linked in this physical universe.
When you do the maths it becomes very clear.
But in everyday life most people are not used to viewing spacetime as the 4 main dimensions we traversing each moment of our life. My location in my account I've had as spacetime to always keep me awake to this reality.

 

[Werewolf]

Interesting read: The block universe theory, where time travel is possible but time passing is an illusion

The idea is that the universe contains all events that ever happen anywhere and at any time, so past, present and future exist simultaneously. Time travel in both directions is possible (still extremely difficult) though you can't go back and change the past.

I guess it's a philosophical discussion as much as a scientific one and possibly something we'll never be able to prove.

 

[GreyCrow]

Interesting read: The block universe theory, where time travel is possible but time passing is an illusion

The idea is that the universe contains all events that ever happen anywhere and at any time, so past, present and future exist simultaneously. Time travel in both directions is possible (still extremely difficult) though you can't go back and change the past.

I guess it's a philosophical discussion as much as a scientific one and possibly something we'll never be able to prove.

As you note its more a philosophical question but I do have this theory as 1 of my multiverse ones. ie Galileo is dropping those weights , as I type , in some other universe.

 

[Werewolf]

As you note its more a philosophical question but I do have this theory as 1 of my multiverse ones. ie Galileo is dropping those weights , as I type , in some other universe.

Yes I've often wondered if the future has "already happened" and clairvoyants can somehow see it, although I don't know of anyone who has predicted the future completely accurately and maybe they perceive the most likely possibilities rather than a definite outcome.

 

[Howard Littlejohn]

does the gravity of the black hole warp space so much that the space itself stretches causing us to experience time differently?

i have read that einstein has proved that all matter is energy, he also states that the faster an object moves, the more energy/mass it gains.
so if we combine these two facts, this means that we can time travel into the future by simply moving at extremely high speeds, right?
it kinda makes sense to me because if the mass of a black whole can distort time, then an object moving fast enough to equal the energy of the black whole would induce the same effect right? from my perspective, if every thing is energy, and mass gains energy the faster it moves, then i think its safe to assume that a object can move fast enough to make its energy equal to a larger mass/energy, right?

I dont know, its just something i am trying to get my head around

Time travel? That depends on what you mean. You continue to travel through time at one second per second. However, from your frame of reference the universe may travel through time much faster than that. Over interstellar distances at very close to light speed, the universe goes through many years to your many seconds. It isn't like hopping in a TARDIS and, bam, the year 2300 - time still happens, just at different rates.
The effect has been measured, in fractions of a second (maybe up to a few seconds), with communications satellites*. While they aren't travelling at even a recognisable fraction of light speed the time differential is enough to show up; given enough time.

It takes an infinite amount of energy any mass to accelerate to the speed of light. (Or, speculatively, decelerate to light speed if something was travelling above light speed to begin with. Relativity doesn't technically rule that out, common sense seems to.)

*There is a common belief that GPS has to account for relativity. One I believed until a moment ago. It turns out this is probably not true. The clocks do run at a different apparent rate due to it, and this may have given rise to the belief. Apparently while it has been measured it is not actually used as part of GPS. So the satellites are impacted by relativity, but GPS doesn't seem to need to account for it.

 

[GreyCrow]

*There is a common belief that GPS has to account for relativity. One I believed until a moment ago. It turns out this is probably not true. The clocks do run at a different apparent rate due to it, and this may have given rise to the belief. Apparently while it has been measured it is not actually used as part of GPS. So the satellites are impacted by relativity, but GPS doesn't seem to need to account for it.

There is an astronaut that has retired who is calculated to be younger than everybody else (relatively) by 0.02 seconds. Thats the difference the satellites roughly calculate to be