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Lightbender

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Just a quick ponderation of sorts (is that a word?). If our good friend Einstein was correct in his theory which is based on the two postulates. That the speed of light in a vacuum is constant and independent of the source or observer. And that the mathematical forms of the laws of physics are invariant in all inertial systems.

 

(takes a breath) if his theory is correct, then is it possible to decrease ones velocity to an extent that one would achieve the exact opposite? Let me know if I'm going out on a limb here...

 

-Ted

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Ponderation sounds like a good word ot me...especially on a Sunday.

 

But I must admit I don't understand the question. What opposite is it you want to achieve?

 

Do you mean decreasing your velocity so that you are completely still, in regards to every possible observer frame and time system?

 

If so, I think it would be a tough task since, considering the expansion of the Universe, you'd be hard pressed to find aby spot in the Universe which is absolutely still. And if you try to decrease your velocity by matching the velocity of the expansion, you are merely moving along with it. If you try to go slower than it, you are simply moving away form the center of the source of expansion at a slower rate - in order to move towards it you will have to accelerate to a speed faster than the rate of expansion.

 

Gödel postulated that if the Universe is rotating, there could be time loops. But even here I don't think the point was that one could come to a complete stand-still, you will *always* be moving in reference to something.

 

(And let's not even start thinking about the Multiverse theory where our Universe is just one of many...)

 

But I am merely rambling here...maybe you could rephrase your question? Opposite to what?

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Mr. "Lightbender" why can you only go as fast as the rste the universe is expanding. Why does Einstien say that it is not posible to travel faster than the speed of light? is it because it would take infinate energey and the universe can't do that? Pardon my "simple" questions im only 13 but highly intrigued.

 

 

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TJ,

 

I think you mistook my input for Lightbender's.

 

The issue here is whether you can actually inverse time dilution (ie, the slowing of time as you accelerate an object) by trying to decelerate insted of accelerate.

 

My response to that was that while you can accelerate towards the speed of light and therefore gradually see a time dilution effect, the opposite is not so simple because you can't *not* move at all. No matter where you are in the Universe, you will always be moving in reference to somehing (for instance, the expansive force of the Universe). So any attempt to try to reduce time dilation by deceleration is simply an act of moving in a different way than before.

 

I would like to point out that of course, if you happen to be travelling *Very* fast, you can easily decelerate and inverse the time dilution - but not to a point where it starts going backwards in time.

 

As regards your question why nothing can move faster than the speed of light, it is simply one of the most basic constituents of Einstein's theory of realtivity. Nothing can move faster than light, because as an object approaches the speed of light, it has to spend so much energy to keep accelerating taht the object itself turns into pure energy. That is what the formula e=mc2 says. A mass moving at the speed of light equals the square of the energy it contains.

 

While it is easy to assume that things can move faster than light, in theory it is impossible.

 

This probably sounds like a jumble of strange ideas...I'll give it a think and see if I can come up with a better answer.

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TJ,

 

Here is a site which may help you help. You might find it a bit challenging (considering your age of course), but try n pick up as much as u can. This is a book which Einstein wrote himself explaining the theory of relativity including the process of deducing the theory. I personally find this the easiest book 2 understand on relativity.

 

http://www.bartleby.com/173/

 

As for your question regarding the speed of light as the speed limit. This can be explained by one of Einstein's questions, the most famous E=mc^2. One interpretation of this equation is that mass and energy are equivalent.

 

As an object moves at a certain speed, it has a certain amount of (kinetic) energy. The faster the object is moving, the larger the amount of energy it has. From this equation, E=mc^2, it can be seen that the mass of the object would increase. At close to the speed of light, the object has a lot of energy and hence a large mass, and needing a large amount of energy to accelerate any further. The energy (hence mass) rapidly increases as u close in on the speed of light and you will need an infinite amount of energy to accerlerate the object anymore because at that speed, its mass is infinite.

 

Lightbender, the opposite of time dilation is time moving faster for your frame of reference relative to the other frames. To achieve this, u will need to accelerate all the frames of reference so that they are moving very fast relative to you. Then THEIR time will be dilated and hence it will seem that your time has been moving faster. The same effect can be achieved by being at rest (or slower than) all other frames of reference.

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  • 2 months later...
  • 3 weeks later...

I aint sure if I am on the right track with this, but by decelleration, you are effectivly halving your velocity at rate x, however, you can never achieve absolute zero by halving, there is always a fraction smaller, just like there is always a bigger fish etc (tacky star wars quote I know).

 

the only way to acieve the exact opposite, is to apply negative accelleration, which is not the same as decelleration. Negative accelleration I think is the same as applying positive accelleration in the opposite direction, in which case you get the same result. Its like saying you can never go backwards, you are always moving forwards in another direction. I get the feeling what you're asking is essentially the same question as "can time move backwards" the answer to that, as I explained in my post on universal contraction, is no. The end result is always the same. possitive accelleration in a different direction.

 

Hope this helps

 

Martin.

 

Quicky to test your brains - science tells us that nothing can move faster than light.......in which case, how can science also tell us that light deccellerates over time? If nothing can move faster than light, then surely light cant either? and if light is deccellerating, would it not eventually get to a point where anything can move faster than it? assuming that the universe is around long enough for it to reach such a point.

 

Answers on a postcard please.

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Martin,

 

I think there is a problem with your theories in that you foresee a Big Crunch while at the same time you maintain that objects cannot come to a halt.

 

What then happens at the moment of the Big Crunch? If the Universe can expand and contract, this is not necessarily due to acceleration or deceleration. Rather, these are simply effects of the expansion and contraction of space-time. What you need is a unification of gravity and space-time at quantum levels...which would possibly be a Theory of everything...to explain the effects of matter and energy upon the shape of the Universe, and which forces are acting to manipulate it both as an ultra-large structure and at subatomic levels. The speed of light is possibly not a constant, but that does not mean that it isn't a fundamental limit in the conversion of matter and energy. It is the basis of E=mc2, which in turn is based upon Newtons laws of motion, with the difference that Newton believed in an absolute time (like you seem to do), whereas Einstein realized that time is relative to the observers position and velocity in space-time.

 

When you state that deceleration will never cause an object to stop because of the inherent properties of fractions, I can prove you wrong by throwing a rock into the air and watch it slowly stop and turn back. In this path there is a moment of absolute rest. It will also hit the ground, which effectively causes it to stop in its relative path. This is due to the force of gravity, and endless fractions have nothing to do with this. As for Lightbender's wish to "decelerate" to a speed which brings him on a path backwards in time, I think it must be based on a misunderstanding, although it was an interesting question...although I didn't understand it. (Like most of us).

 

Oh, I'll just shut up and go to bed. Until later,

 

Tormod

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I can prove you wrong by throwing a rock into the air and watch it slowly stop and turn back. In this path there is a moment of absolute rest. It will also hit the ground, which effectively causes it to stop in its relative path

 

I understand what you mean by this, and at the same time, I'm not sure if either of us are on the right track. Is the moment of absolute rest absolute? after all, the rock appears to stop dead in space, but only because the forces acting upon it are equal. Eventually one of the forces will win out, eg. gravity. Yes, eventually it will hit the ground, stopping it in its reletive path, but it still has a lot of energy from its mass/velocity ratio, so it bounces in order to lose the excess energy.

If you were to dig a hole under the rock, it will again fall. and, whilst gravity exists and surfaces to block it dont, it will keep on falling.

 

However, I thnk what I was getting at is that an object can deccellerate at rate x forever and never reach absolute rest, until another force acts upon it in the opposite direction, sorry, I'm not that good at explaining what I'm thinking at any particular moment. Unless you bring another force into play, you can decellerate as much as you want, you will never stop.

 

But, as you say, eventually gravity will come into play. Theres just no escaping it. Infinite decelleration works fine on paper, but it can never be proved practically, unless someone invents a way of cancelling out gravity.

 

Time

Hmm. I soppose in a way I actually believe in both absolute and reletive time. Reason? if absolute time didnt exist, then nor could relative time.

 

2 clocks on 2 spaceships - different velocities and positions. now, when you bring both clocks together, they are going to give different times, as in conjuction with Einsteins theory, but, at what point were they set? and how do you know that they are not both telling the correct time? for this to work you need an absolute time base. Or am I off on completely the wrong track. Its like I said in the extract posted with the "Universe is Contracting" statement. Time its self is absolute, but events can alter relative to one another giving the impression of relative time. If this doesnt explain it, sorry, I dont know how to say what I'm thinking better. What I'd give to be telepathic lol.

 

Hope this has helped.

 

Martin

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Martin,

 

time is not absolute. The only way to know that the clocks started out at the same time, is to be absolutely sure that they were set within the same frame from an observer's point of view in space-time. The best way to understand this is really to read some of Einstein's writings on relativity. Stephen Hawking covers much of it in A Brief History of Time, and also in his recent book The Universe in a Nutshell. David Bodanis covers it in a very accessible manner in his "E=mc2: the bioagraphy of an equation". Recommended!

 

I think perhaps you misunderstand (no offense!) the notion of "absolute" time. It is a term used to state that time has no beginning, no end, and that it always flows at a constant rate, no matter where you are in the Universe. If time is absolute, the Big Bang was not the beginning of it, and the Big Crunch will not be the end of it. In modern cosmology, absolute time has been abandoned.

 

Why? Because Einstein proved that time is relative. Relative to what? To the observer. Time flows differently if you're near a strong gravity well (like a black hole), or when you move at great speeds. Therefore, as you approach the speed of light, the flow of time changes drastically. But not for the object that is approaching the speed of light - but for an observer observing you moving at a relativistic speed.

 

In fact, a person living at sea level and another who spends his entire life on the top of a mountain, will not notice that in fact the flow of time is minutely different. But it is. But in both person's frame of observation, it is _the other_ person's time that has changed.

 

According to modern physics, there is no absolute time. If there was, you would have to explain what this absolute time is based upon. Is it the decay rate of protons? They did not exist before the Big Bang. Is it the expansion of space-time? It started right after the Big Bang. Is it causality (cause and effect)? Then what caused the Big Bang must have set an absolute time - which means that the absolute time is indeed relative to something. Is it the hour, minute, second? No, they are only cultural time-items based on the circling of our planet around a single star.

 

So time will flow differently according the where and when you are in the Universe.

 

Perhaps a better question to ask would be "what is time" - to which I have seen as many answers as there are stars in the sky.

 

Tormod

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  • 4 months later...

hey guys...i was wondering wat u meant by, reversing time dilation. Because even IF u can come to an absolute stop, that just means your velocity is 0, and time dilation is zero. Even if ur velocity is negative (direction of displacement), the formula for time dilation squares ur velocity so u can't go negative. at most, i agree with michaelchang about dilating everyone else's time to so u seem to move faster. just wondering, why do u want to move slower than everyone else, to observe something in slow motion????

 

forgive me if i'm wrong. i'm just a curious 15 year old teen trying to understand teh universe

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  • 3 weeks later...

Hello

Well I have some questions about Albert Einstein's theory due which still I am disagreeing with him. I will discuss that after sometime. Well let me increase your knowledge a bit speed of light is not the fastest now. Speed of Gravity is the fastest. Einstein ,I don't know y he never thought of that as he was the one who have worked alot on Gravity after Sir Isaac Newton. As whole General Relativity is based on it. There are few rules of Physics and a person should keep them mind. One of them is that if one thing happens its converse is also conisdered as possible. For example

E=mc2 , it says that matter is changed into energy when it moves with speed of light here i am not talking about that whether it is right or possible or not and whether it is practically proved or not this is what Albert Einstein says so according to Physics it's converse will also be, i am using will also be not it will , it's converse will also be possilbe that energy can be converted into matter. In easy words matter and energy r same means both can be converted. Another example is of Space-Time. I guess someone was talking about that a person should get slowed down or come to rest well this is can be explained by the thing which is called ""Frame of Reference"" which Sir Isaac Netwon didn't explain in his Laws of Motion. Einstein explained Frame of referecne wat is it. And nothing is at rest and cannot be because Universe is continously expanding. Second thing to go in past is possible using worm holes but there are alot disadvantages of it. One of them is that the matter of which it is made up of is not stable and secondly one cannot come back once went back in past and Scientists are not sure yet whether the person going in past could be able to speak to others there are not sure because one of the theory behind is that one couldn't change the history because that would be against the Laws of Physics. If you want to know how Speed of Light is not the fastest I can explain that If you do not understand.Remember one thing in Science which is not proved that it is right and which is also not proved as wrong is considered as correct because it is not proved wrong. If you any questions to ask me you can ask me. Thanks.

Bye

M.Janjua

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  • 1 month later...

Hi mjanj. I was just wondering what were the questions behind your post. I didn't really catch them. On a side thought, wormholes can be stablised by using exotic matter (matter with negative mass).

And I always thought the speed of light is the speed of gravity so can you explain that part?

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