Time, Relativity thing

In this thread, I just wanted to confirm a few things that I was unsure about and ask a few questions.

My mind is a bit scrambled up with this Time, Relativity thing.
I just want ask how light and time are related, and could someone explain a few basic principles of Special Relativity to me.



[edit on 5-8-2005 by siddharthsma]

Now you've done it Sid

The RSGs [real smart guys] will be here soon.

My take on it is that light and time are not related in the least because light is a particle/wave and time is just an illusion that humans use to make the universe understandable. Thus time, light, space aren't relatives, they've never even been properly introduced.

[edit on 5-8-2005 by whaaa]

Hmmm....

Time and light from my so far novice experience aren't necessarily related. Light (photon) is a moving massless (so far) body which time has the ability to measure certain properties, mainly its propulsion through space. Some people (not myself) seem to think that the speed of light allows for time travel, still yet unproven in practice. Called time dialation.

SR deals with one body in motion relative to the reference frame of a body not in motion. You might get better results from someone who believes wholeheartedly in Einstein's methods and philosophy. Actually, Einstein wrote a book on SR, several edition, cost you about $7 at a used book store.

It still amazes me that Einstein needed two methods of relativity to get his point across. Seems rather bizare wouldn't you think?

How light and time are related?? Its not so much the particle photon thats related to time, its the fact that its massless and travels at a theoretical maximum speed of the universe through a vacuume. At normal speeds in day to day life we dont notice much time dilation but at greater speeds time will move slower in our frame of reference(compared to others, to us it would be going normal, but elsewhere it would be going faster)
It is assumed that at light speed time around you would go incredibly fast. Not sure if our time would completely stop altogether(compared again to another framepoints perspective)

Basically, time gets slower(relatively) the faster we go, so at light speed it should come to a near halt(relatively)

Am i correct? Please correct me if i am wrong.

You sure got that right. After all my research into matters above and beyond I cannot comprehend non-linear time. Forget about mixing that with light!

Dallas

quiksilver, bang on. Allthough I believe Time actually stops for the person going the speed of c. Another trippy part of Relativity is if we found a way to go faster then light we would effectively start travelling backwards in time. Not sure if that is what would actually happen but that's what Einsteins equations seemed to suggest(and the subsequent follow-up also solved the Causality problem when doing such a feat, too bad it requires huge amounts of energy and exotic matter to achieve lol)

Imagine sending a sattelite with an enourmous mirror out in space. The mirror will always point toward earth, reflecting earth itself. The craft should move faster than light. As time passes, scientist on earth discovers even more and more sophisticated instruments to catch the light returned from the mirror on the spacecraft. So, in theory it would be possible to look back in time?

No. Since the light will never hit the mirror, because its travelling faster than light?

So if the mirror was stopped abrubtly after 1000 years of travelling, it would have reached far enough away to catch the light from the past?

Btw.. does time have a weight?

[edit on 5-8-2005 by Ingolf]

Brings back memories of my modern physics course...

Special relativity is actually pretty easy. The equations are simple, the concepts are the only thing that are tough to swallow for alot of people. I would suggest picking up a book and reading about it, as it'll be easier to understand with equations (the math alone explains everything you need to know).

Originally posted by sardion2000
Another trippy part of Relativity is if we found a way to go faster then light we would effectively start travelling backwards in time.

Going faster than light would mean you'd have imaginary time i.e. 4seconds + 5iseconds. Which doesn't happen. Good proof for no FTL travel.

Ok. Time and light aren't related, time and the speed of light are. Simply put, if you go faster (closer to the speed of light), then the passing of time slows down to you compared to someone who isn't moving.

What special relativity says is basically two things:
1. Speed of light is constant, no matter what
2. The same physical laws apply no matter where you are. Basically, physics doesn't change.

You can read a lot more here. (I sooo love wikipedia's naming of their articles)

didnt einstien have a theory on time viewing to that if you could see around the curvature of the universe you could see the past ect?

Originally posted by siddharthsma
My mind is a bit scrambled up with this Time, Relativity thing.
I just want ask how light and time are related, and could someone explain a few basic principles of Special Relativity to me.

I'll refer you to my post on this thread, which was largely ignored in favor of what someone's mom said.

www.abovetopsecret.com...

Relativistic Monkeys, not just for perspective anymore...

Originally posted by Annacryst
didnt einstien have a theory on time viewing to that if you could see around the curvature of the universe you could see the past ect?

Everything you see is in the past. Everything.

Einstein had a theory that gravity would allow you to see things by bending space. It's called gravitational lensing. Basically, a heavy object exists, and when light from an object goes past it, it bends the light, so an observer sees the object in a different place than normal, or, sometimes, multiple times, usually in the shape of a ring.

So basically there is space and there is time.

In most engineering applications they can be considered independent entities. For example, your notion of time is something that is imposed by humans to track the passage of, well, time, as in like the seconds ticking on a clock.

The way we typically understand time is a certain metric that on our planet at our average ambient temperature, and velocity through the universe, and with our standard materials available to us here (such as the cesium atomic standard) we can create a metric that is very stable.

The only problem is at very high speeds strange things start happening.


It became convenient to Einstein and others to describe what happens at high velocities by actually changing the definition of time. So when people talk about space-time curvature they are discussing the solution space of their geometry, sort of like warping a donut (torus).


But not even Einstein knew what we do now about particle physics. For example, a photon (light particle) is considered to be massless. But, yet light bends around large masses like stars and gets sucked into black holes.

I have a genius buddy of mine who is a theoretical physicist. Basically, he explained to me that light "turns" into a black hole. I gather it has to do with angular momentum and spin. Photons have 1 spin (electrons have 1/2 spin). Gravitons have 2 spin.

It gets pretty hairy from here, but hopefully that's a starting point for you ...

Okay prepare yourself for some heavy concepts.

Step 1) The difference between relativity and special relativity.

Einstein had 2 theories of relativity. The first theory term just General Theory of Relativity is a theory that involces mass and light and proposed that matter causes space to curve. The famous equation E=Mc^2 was the final outcome of this theory. E= enery, M= mass, c=the constant of the speed of light.

What this equation dictates is that as mass approaches the speed of light, it will turn towards pure energy rather than mass. It also predicts that travel faster than the speed of light is impossible. Why? As I stated before, as mass (or a ship) approaches the speed of light, the mass will also increase. The amount of power to keep this object going also increases. (because you are going faster and your mass is increasing until you don't have enough power to push this growing mass faster). The theory states that once the mass reaches the speed of light, it then turns into pure energy (or elctomagnetic wave particles i.e. light)

Now onto the relativity term. Relativity states that everything in space (space not meaning outer space, space meaning the area an object takes up, i.e. volume) can only be observed from exactly one other point in space, and those two spaces are relative to each other. So basically, if I were on a space ship moving at 300mph, and you were on a stationary space ship watching me race by, I am going 300MPH relative to your position. Now lets take that same example, and instead of being on your own ship, you are now in my ship, and we are both going 300mph. If I were standing next to you, then my speed is 0mph. (we are standing next to each other both going 300MPH) So relative to you in this case, I am not moving.

So this is basic relativity. It basically says that everything in space is relative to each other and nothing more.

Now on to the Special theory of relativity.

The special theory of relativity adds one more thing to the equation, and was actually never finished by Einstein. (He later called it one of his life's biggest failures)

What did he try to add into it?

Gravity

You see, gravity screws up everything and warps spacetime. Gravity effects time, mass, energy, and even light. Gravity is one of the great mysteries in thoeretical physics, and is said to be the ultimate bottom line towards getting the GUT (Grand unified Theory) of the cosmos.

Gravity affects time in what is called gravitational Time Dialation. GTD says that gravity effects spacetime relative to other objects in space. Here is an example:

If I were to build a space ship, and say goodbye to you and fly off to the outer rim (event horizon) of a black hole, my time relative to you would increase. ie one year for me would be multiple years for you. The greater gravity is for me, the slower time will go for me relative to the you in a less gravity situation. This has actually been proven by the Hafele and Keating Experiment. A good explanation can be found here, and info on the experiment can be found here.

This gravitational time dialtion is what many refer to as the "Time machine" syndrome in which one can travel into the future.


I guess that is enough info for now.
xmad

Special relativity came first...general relativity is the more confusing of the two, mathematically anyhow...your post kind of sounds like you think Einstein came up with general first.

Originally posted by Amorymeltzer

Originally posted by Annacryst
didnt einstien have a theory on time viewing to that if you could see around the curvature of the universe you could see the past ect?

Everything you see is in the past. Everything.

Einstein had a theory that gravity would allow you to see things by bending space. It's called gravitational lensing. Basically, a heavy object exists, and when light from an object goes past it, it bends the light, so an observer sees the object in a different place than normal, or, sometimes, multiple times, usually in the shape of a ring.

If I were to build a space ship, and say goodbye to you and fly off to the outer rim (event horizon) of a black hole, my time relative to you would increase. ie one year for me would be multiple years for you. The greater gravity is for me, the slower time will go for me relative to the you in a less gravity situation. This has actually been proven by the Hafele and Keating Experiment. A good explanation can be found here, and info on the experiment can be found here.

so does that mean when on a the moon or planet of lesser gravity time would actually seem to be moveing faster than those of us on lates say earth?



ahh that makes sense thanks. did he or anyone for the matter ever speculate that maby the cosmos has a toroidal shape to it?

[edit on 5-8-2005 by Annacryst]

Originally posted by Annacryst
If I were to build a space ship, and say goodbye to you and fly off to the outer rim (event horizon) of a black hole, my time relative to you would increase.

No it wouldn't, your speed would stay relative to us.

ie one year for me would be multiple years for you.

This is still a theory that has yet to be proven.

The greater gravity is for me, the slower time will go for me relative to the you in a less gravity situation.

I find this hard to understand. Are you stating the greater the gravity or the greater the increase of gravity?

This has actually been proven by the Hafele and Keating Experiment.

The problem in this experiment was the use of cessium atomic clocks and the lack of stability.


EDIT: Attributed to post above his.

[edit on 5-8-2005 by Frosty]

i copied that from the post above and was asking questions

There is no such thing as time...

.
Light is a constant. [EM - electromagnetic radiation is a constant speed]

Space & Time [Space-Time] are/is morphable back and forth into one another. [They are NOT constant separately, but are a constant when combined]
Think of a hinged frame work that you can wrack/bend back and forth.

I believe ones relationship to Space-time is a constant.
ie. you move more/faster in space you move slower in time and visa-versa.

Who thinks space is constructed of zero energy EM radiation? [Ultra long wavelengths, almost flat]

gamma rays, X-rays, UV, light, Infra-red, microwaves, radio waves, gravity waves, flat [Universe curve] EM = space? (Absolute [more than Universe] flat EM = time?)

Would the absolute flat EM be 'time' that forces the Universe to expand. So time [straight flat lines] is driving the expansion of the curve of the Universe?
.