Is Spacetime Real or Just an Idea?

[Stewart101]

I have just watched that show 'sci fi science', and to me it just does not make sense. He said that in the future we will be able to manipulate space and time, but how can they exist. Space is nothing, and time is an idea created by us. I can only think that space-time is something which matter exists inside. But even then, how could it be possible to manipulate it. The guy on the show said we can do this using negative energy, but for that to work, wouldn't space-time have to be energy in the first place? which it isn't. If someone understands this more, please explain this to me, and anyone else confused by it.
Thanks,
Jake..

 

[faen]

You can perceive space as the cause of matter having different positions. Matter is just energy which can accelerate relative to other matter. Fundamentally matter and space is much the same. That would be quantum states. This is why, a particle may be created out of space alone because of uncertainty relation between energy and time, much like Heisenbergs uncertainty principle. I forgot the formula, but it translates that within a short enough amount of time, there can be a large energy (large insecurity in energy existence). So in a small amount of time, an energy E comes to existence and becomes matter.

As for time it is an interresting subject. Some say time is just a quantum mechanical statistical effect. But I've always perceived it as something similar to space, but is the cause of matter having different velocities and that everything doesn't happen all at once.

 

[bapowell]

Space is nothing, and time is an idea created by us.

First of all, it was a sci fi show. That being said, it isn't factual. We might one day learn to manipulate spacetime, we might not. As for your above comment, I'd caution you to be a bit more careful with your claims, as both ideas have been pondered by philosophers and scientists alike for centuries. As far as space is concerned, Einstein showed us that it is quite real. The geometry of spacetime manifests itself as gravity. Your body manipulates spacetime right now by virtue of the fact that you have mass. The Earth manipulates spacetime -- it causes it to bend with the result that apples fall from trees and clocks on satellites record different times depending on their distance from Earth, for example.

As for time, why do say that humans invented it? What is your definition time?

 

[bugglue]

I am not quite sure and wish i knew more about this but here is what i think. ( I too saw the show and I didn't get it all. )

Well this might be how it works but please don't flame if it isn't how.
What I believe is that maybe just maybe somehow that negative energy makes the spaceship somehow have huge gravity so then time would be moving very very slow and the space between the plants stars and everything for a huge radius would be compressed so much it comes closer to us then the gravity would be turned off and the space would uncompress moving out very fast and imagin as if were were riding a converyor belt. ( I have no clue if any of this might be true just my thought on the topic ) So then maybe space would expand maybe faster then the speed of light.
( Don't know if any of that makes any sense. )
If you enjoy this kind of thing I would suggest you watch "The Univers" on the history channle.

 

[bugglue]

As for time, why do say that humans invented it? What is your definition time?

My definition of time would be something as the period between events but that would not really work.

 

[LostConjugate]

Time comes about the following way. You see things moving at different rates through space. So you take one object and you invent a unit of time and call it the second. When this object covers 1 unit of space you declare that 1 second. Now compare everything else to the rate that object moves, create other things that move at the same rate and call them watches. Time is a natural way of comparing movement, however the result is that in different reference frames time becomes relative.

A 4 dimensional space-time is not a new concept. When you invite someone to your party, it requires all 4 dimensions for proper directions. You must tell them what street it is on, the cross street, the floor number, and the time the party is taking place.

Instead of the time the party is taking place you could also say when the sun goes down, because this is the same thing, you are using comparison of movement for the 4th dimension.

 

[Eynstone]

I guess the show had some far-fetched conclusions form General Relativity ; another
sci-flim-flam.
Your ideas of space & time have some truth. As Einstein said, space,time & other fundamental concepts are no more abstract than clothes - the latter are modeled to fit our body, the former our experience.
This, I'd say, is a reciprocal process.We no longer model spacetime as absolute or homogeneous as there's evidence (and a consistent theory) against it. On the discovery of CP violation, another idea was forgone & we had a better model.This will continue (atleast in the scientific mode of discovery) & the ideas of space-time will never be 'consummate'.

 

[silentbob14]

Well, I guess the fact that bodies with mass bend space-time suggest that space-time isn't nothing. The same is with time, as we all know time moves slower for fast moving objects, so i guess time is not nothing, because it can be manipulated in such way. Though, it's only my opinion.

 

[bapowell]

Well, I guess the fact that bodies with mass bend space-time suggest that space-time isn't nothing. The same is with time, as we all know time moves slower for fast moving objects, so i guess time is not nothing, because it can be manipulated in such way. Though, it's only my opinion.

No silentbob, you got it right. It might be your opinion, but that's also a fact.

 

[Frame Dragger]

Well, I guess the fact that bodies with mass bend space-time suggest that space-time isn't nothing. The same is with time, as we all know time moves slower for fast moving objects, so i guess time is not nothing, because it can be manipulated in such way. Though, it's only my opinion.

That's a bit of a strange vision of time, but it's closer to the notion of spacetime as a single THING, the geometry of which determines the path 'stuff' takes through it. It's true as with the case of Differential Aging/Time Dilation that this isn't just percieved.

http://www.utc.edu/Faculty/LingJun-Wang/Paradox.pdf

and

https://www.physicsforums.com/showthread.php?t=371151

may be helpful.

 

[bapowell]

The magic word here is spacetime. If we accept space as being in some sense 'real', then so must be time, as these are inextricably combined once we establish that the axioms of special relativity are true for all inertial observers. In general relativity, spacetime becomes dynamical. Both space and time can be curved, with physical manifestations. As mentioned, time dilates in gravitational potential wells. I don't see how a made-up concept can dilate in a potential well.