Special Relativity for Hopeless Morons?

[DrProctopus]

In truth, I do not get Special Relativity (or General Relativity) on it's most basic level. Would someone mind explaining it with small words?

 

Whenever I read physics, I can never get past certain basic concepts that always just seem wrong to me.

 

For example, supposedly relative motion is such that there is no difference between me moving past a space ship, and a space ship moving past me. This does not seem right to me, because of my probably nutty understanding of reality:

 

1) Matter is a pattern of information encoded in the fabric of space-time.

2) When matter moves, what is really happening is that the information that defines that matter is moving from one location in space-time to another location in space-time.

 

So, if I am standing absolutely still, relative to the fabric of space-time, and a spaceship flies past me, then the information that defines the spaceship is changing from one general location in spacetime to another general location in spacetime. On the other hand, the information the defines me is staying in the same general location in spacetime. If the reverse happened, then my information would be changing general location in spacetime, and the spacehip's information would be staying local.

 

We cannot say that all motion is relative, because all motion can be measured against the fabric of spacetime (and in fact, all motion is a result of the transfer of information through spacetime). There would be a definite difference between me flying past the spaceship and the spaceship flying past me.

 

So, what is wrong with my understanding?

[UncleAl]

So, if I am standing absolutely still, relative to the fabric of space-time,

Spacetime is without background; it is a tensor theory. All motion is arbitrary. There is no "fabric of spacetime."

[CraigD]

So, if I am standing absolutely still, relative to the fabric of space-time

Spacetime is without background; it is a tensor theory. All motion is arbitrary. There is no "fabric of spacetime."

So, what is wrong with my understanding?

About 120 years ago, your understanding of space would have agreed reasonably with most physicists’. Then the Michelson-Morley experiment happened, falsifying the theory of “absolute space”. Special Relativity is what arose to replace it.

 

Strange, but true, and very beautiful. Enjoy.

[Turtle]

___I consider myself a hopeful moron; science is amendable -always-. You never win if you don't buy a ticket.

___Use the search function on this site to find relavent posts to your interest; then read them. Part of the essence of Hypography is the Hyperlink, & many of the threads have links to the pertinent pages.

___Remember the internet has its origin with scientists. It is constructed for sharing information quickly. Again, science is always amendable -always-. :hihi:

[Buffy]

I'll try to contribute more as I have time, but keep this in your mind, "If you think it makes sense, then you clearly don't understand it." (quote attributed to Feynman, Fermi and many others in various forms and referring to quantum mechanics, but I find it relatively relevant for Relativity)...

 

Here's one: yes, time is variable. It depends on the observer. YOUR time is never variable, it always looks the same to you, but when you look at other people's clocks who are moving relatively to you, they certainly won't keep the same time. If you can wrap your head around that one idea, you're half way there.

 

Cheers,

Buffy

[Turtle]

I'll try to contribute more as I have time, but keep this in your mind, "If you think it makes sense, then you clearly don't understand it." (quote attributed to Feynman, Fermi and many others in various forms and referring to quantum mechanics, but I find it relatively relevant for Relativity)...

 

Here's one: yes, time is variable. It depends on the observer. YOUR time is never variable, it always looks the same to you, but when you look at other people's clocks who are moving relatively to you, they certainly won't keep the same time. If you can wrap your head around that one idea, you're half way there.

 

Cheers,

Buffy

___I say it clearly is a pattern; I don't always say it makes sense. ;)

___My clock does not always look the same to me :hihi: ; time flies when I Hypogrophize (or otherwise engage my 'intellect'), & drags when I get depressed.

[DrProctopus]

There is no "fabric of spacetime

 

Hmmmm....

 

I have read a lot of physics-for-laypeople type of articles and books, and they all refer to a fabric of space-time.

 

If gravity is curved space, how can it be curved if it does not exist?

 

 

I understand that this is not the same concept as the aether. The Michelson-Morley experiment was looking at something very different from spacetime.

 

My understanding of the fabric of spacetime is that it is neither matter nor energy. Rather, it is the framework in which matter and energy is defined. Is this correct?

 

 

 

Thinking in terms of a fabric of spacetime, things like a light-speed limit and time-dilation make perfect sense to me. Without it, I see no mechanism of action for a maximum speed or for time dilation.

[C1ay]

Hmmmm....

 

I have read a lot of physics-for-laypeople type of articles and books, and they all refer to a fabric of space-time.

In 1916, Albert Einstein published his famous Theory of General Relativity. His theory describes how spacetime is affected by mass. We can think of spacetime as a fabric that bends or curves when we place an object on it. Keep in mind that the 2-dimensional fabric analogy is just a model we use to represent what is actually 4-dimensional spacetime (the normal three dimensions of space, plus a fourth dimension of time)....

 

More....

It's just a figure of speech, there is no real "fabric" of spacetime.

[DrProctopus]

Here's one: yes, time is variable. It depends on the observer. YOUR time is never variable, it always looks the same to you, but when you look at other people's clocks who are moving relatively to you, they certainly won't keep the same time. If you can wrap your head around that one idea, you're half way there.

 

Hi Buffy,

 

I can get my head around that concept, but only by invoking a fabric of space-time.

 

What makes sense to me is this:

 

- The fabric of spacetime is a framework, composed of a large collection of some smallest possible unit - like a pixel - for fun lets call it a spixel (space-Time Pixel) (I realize it is not that simple, and that we would have to get into string theory for attempts at examining the construction of spacetime - but I really don't wish to attempt to get into string theory)

 

- Each spixel holds information about at least 4 interconnected variables, plus a number of non interconnected variables. The interconnected variables form the three dimensions of space and the 1 dimension of time (that we perceive). The non-interconnected variables store information about various properties that are used to define matter and energy at that point in spacetime.

 

- There is one speed in the universe - the amount of time it takes for information to transfer from one spixel to another - energy in the form of a wave moves at this speed - basically, the transfer of information from one spixel to another takes exactly 1 unit of time

 

- matter is the same as energy, except that the information components that make up matter are moving around in a very localized pattern

 

- the faster you move through spacetime, the more units of time are used in transferring information from one region of space-time to another region of space-time. This means that all internal motion within the object that is moving is slowed down, because there are less available units of time to define that motion. A person moving at this speed would not perceive the slowing of time, because the processes that define his perception would be slowed down by exactly the same amount. Thus, local perception and measuring of time would not change, but an outside observer would be able to detect the difference.

 

- Matter cannot move at the maximum speed. The information components of matter that define the elementary particles need to consume some units of time in order to stay in motion. If you forced it to move at light speed, it would have no time units available for the internal motion needed to define elementary particles, and thus would have to be converted into energy. The pattern of information transfer that defines elementary particles works to prevent this from happening.

 

 

I shared this with a guy who describes himself as an information physicist - he said this is bgenerally the same as his understanding. He then went on to explain the same idea in very complex terms, with lots of math I did not understand and concepts that made my brain want to drip out of my nose.

 

 

So, if the fabric of spacetime is not responsible for the lightspeed limit and time-dilation, then what is?

[DrProctopus]

It's just a figure of speech, there is no real "fabric" of spacetime.

 

It isn't a real "fabric", of course, but the article you mentioned certainly describes it as a real thing.

[GAHD]

Seems to me you're thinking in terms of aether. Am I right?

[DrProctopus]

Seems to me you're thinking in terms of aether. Am I right?

 

Not at all.

 

The aether was envisioned as a substance. I am not thinking of a substance. I am thinking of a framework in which substances are defined. Very different.

 

The aether was supposed to be a substance, and the Earth moving through it would create a wind.

 

As for spacetime - picture this admittedly poor analogy.

 

You create a three-D world inside a computer. Spacetime, in this example, would be those aspects of the program and data that define the objects that compose the 3D world.

 

This is not to say that spacetime is really a computer program, just to explain the difference between a substance, and a thing that defines a substance. Matter and energy are patterns of information. That information is stored, processed, and transferred within spacetime.

 

Very different from the concept of aether.

[Qfwfq]

About 120 years ago, your understanding of space would have agreed reasonably with most physicists’. Then the Michelson-Morley experiment happened, falsifying the theory of “absolute space”. Special Relativity is what arose to replace it.

Not historically exact. :hihi:

 

It was Maxwell's equations that put the principle of relativity into crisis. If this hadn't been considered such an incongruity, people wouldn't have bent over backward so much and the results of M&M wouldn't have struck up such a hoo-ha.

 

Galileo and Newton (in the 16 hundreds!!! :hihi: ) realized that we can't distinguish straight uniform motion from rest. They were not quite so bold as to assert there being no such thing as absolute rest, actually it wouldn't have yet been reasonable back then, and Newton was aware of the difference when talking about rotation.

[Qfwfq]

The aether was envisioned as a substance. I am not thinking of a substance. I am thinking of a framework in which substances are defined. Very different.

 

The aether was supposed to be a substance, and the Earth moving through it would create a wind.

Yes and no. Opinions varied.

 

It's a subtle difference, but viewing it as a substance would actually have been a possible way of saving the principle of relativity. Indeed one of the proposed patches after M&M was that Earth's motion might drag the æther but this wasn't satisfactory.

 

The term, after Maxwell's equations, was somewhat more used as a name for absolute coordinates, independently of being a substance of any kind, this was an actual denial of the principle of relativity. Even more subtle, the denial wouldn't be so much in the existance of absolute rest but the fact that physical law could distinguish absolute rest and motion. This is very subtle, the point of view in modern epistemology is that we consider absolute rest to exist if and only if a way exists to distinguish it.