A four dimensional universe

Has anyone ever heard of any significance of saying we live in four dimensions? are there any implications at all? And is it not true that the energy expanding away from an object that is its time future present and past has its own x,y,z, coordinates in space that change at 186,000 miles per second?

The only implication I can think of is that it means light travels through space.

 

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Time is also a dimension, so we already live in four dimensions.

 

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Was that meant to mean something?

 

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If you want to show up at a party, you need to know where it is and when it is. We, of planet Earth have a privileged notion of what "when" is, called UTC, but as it turns out such human conventions have no great specialness to the universe. Thus rather than splitting up the four numbers into 3 of localization in space and 1 of localization in time, physics (GR) instructs us that any smooth way of uniquely assigning four numbers will do. (Sort of like how UK house numbers need not follow a centralized plan in order to be useful.)

Meanwhile, in certain US cities (mostly in the West) a rigid system for naming roads and buildings means just by knowing the address one can know the relative distance and direction. This is more akin to the Cartesian coordinates of Special Relativity which are restricted to those where inertial motions have the algebraic expression of straight Euclidian lines in four dimensions. Just as the geometry of the city allows more than one grid system, so does the physics of SR allow more than one choice of which motions are to be considered as "at rest". Such a choice influences both where "where?" and "how far?" means but also "when?" and "how long?". Nevertheless, once such a choice has been made, four numbers, x,y,z and t suffice to identify any potential party.

 

So people who don't have anything scheduled are in a three dimensional universe?
Well if your going to say that the light coming off an object is a dimension why not say too that sound is a marker of their position as well it just travels a lot slower then light, or gravity waves of their location, are runners who start at the sound of a gun in the 5th dimension since there sceduled moment was determined by sound?

 

Don't be ridiculous, we all exist in time.

Light isn't a dimension.

 

Such people are delusional for at a minimum they have a final appointment scheduled. NADT.

I didn't say that and I would never say that. A "dimension" is a degree of freedom in some geometry. So four-dimensional space-time requires four numbers to specify (remove) all freedoms and localize to the tiniest portion of the geometry, a point-like event.

Not actually a cogent argument.

If you want to try to localize something via coordination of numbered wavefronts, the intersection of forward signal-cones requires n for n-dimensional space time. Light is not special in that regard.

Example:
\(x^2 + y^2 + z^2 - (t-5)^2 = 0, \\ (x-4)^2 + (y-3)^2 + (z-8)^2 - (t-7)^2 = 0, \\ (x+4)^2 + (y-7)^2 + (z+8)^2 - (t-3)^2 = 0, \\ (x-7)^2 + (y-12)^2 + (z+4)^2 - (t-4)^2 = 0\)
has one mutual solution in the future of points \((0,0,0,5), \; (4,3,8,7), \; (-4,7,-8,3), \; (7,12,-4,4)\) : \(\left(-\frac{33}{18}, \frac{189}{18}, \frac{44+5 \sqrt{103}}{18} , \frac{101+20 \sqrt{103}}{18} \right)\).

 

people should be banned from this forum for giving definitive yes or no answers without ANY logical reason or arguement. Please enlighten me Dwiddler, what do you mean by light is not a dimension? Is it not said that time is the fourth dimension and is time not associated with the speed of light?

well as long as you throw in some math equations I'll believe you if you tell me I'm a turtle with wings flying to my castle in the clouds.

Frankly I would like to get back to what I was discussing if you guys could just respect that. Another example, If I'm using sound waves to find something, say church bells, rather then a clock, does or does not the location of the church determined by its sound? thereby giving away its coordinates by the new 5th dimension of sound?

 

The wavefront of an expanding signal in n-dimensional space-time is a (n-1)-dimensional surface and so you need a minimum of n such surfaces to localize a single event in space-time. For well-behaved light-cones with no degeneracies, n such cones suffice. The example was germane to that basic statement about dimensionality.

The church is remote to the person hearing the sound. typically you need a minimum of two detectors to estimate direction (poorly) and that does not give you an a priori estimate of distance. Humans have two ears which doesn't let them locate even directions with high fidelity.

No such thing. You don't need a 5th coordinate in four-dimensional space time. More information is simply redundant.

 

Then what was YOUR logical reason/ argument for saying it could be?

I suggest you apply yourself and learn what "dimension" means.

Time is A fourth dimension - it depends on what's under consideration.

No more that it's associated with any other speed.

Sound isn't a dimension.

 

Hey Trevor, I reported this since it is a clear violation of site rules.

 

Is not saying "time" often meant to really convey the idea of movement through time? " time is associated with the speed of light (photons), that photons have zero travel through time, and where would we be without the speed of light 300k/sec squared? or?

 

if that's in violation of the site rules you guys should be banned from your countries

 

That makes about as much sense as a soup sandwich.

 

Anyways back to the OP, now lets say your looking at a planet that's ten light minutes away. It's x,y,z coordinates in your vision is determined by it's light coordinate or time when in reality at the moment you are looking at it the planet is ten minutes ahead in its orbit. time therefore gives a false x,y,z coordinate. its time hasn't reached us but it's gravity waves may travel several times the speed of light so would not its gravity waves coming from it be a more accurate coordinate of where and when it is creating 6 dimensions as well as sound?
example: sound perpetuates in a wave form just like light from any object. If sound was all you had to keep time it work just as well.

 

Gravity - to our best knowledge - travels at light speed.
Gravity is not a dimension.

 

When you treat time as a dimension using (x, y, z, t) as coordinates, you are describing a static universe. There is no motion.

This can be a useful model allowing the use of various well established & studied mathematical disciplines to analyze the lase of physics, m ost notably Differential Geometry.

 

Rather, you have a framework to describe the past, present and future as peers of one another.
We still have motion, but it has a different representation than dynamical changes. Much like a movie real has a representation of motion even when it is still in the can.

 

Thanks rpenner. And another argument for the OP, does not smell radiate from objects just as light, sound and gravity waves? If I'm a bear finding some pray with scent, does that not indicate its coordinates as well? I think that makes 7 dimensions that can be used to give coordinates. But I guess in argument maybe not that bear who walks around on two legs as one can see in photos of him he constantly checks his watch make sure he ain't late to his date in the square.

 

Smell isn't a dimension.

Saying that a smell is a dimension because it can be used to locate something is like saying an arrow is a dimension because it points that way.