why is it not possible to travel at the speed of light? plz explain keepingE=mc squared in mind.?

Question

plz explain using einsteins formula. i know most of the basics. all about energy and all. but plz explain keeping in mind that im only a 15 yr old!
not sum PhD doctorate
thx :)

Answer 1

Since Einsteins general relativity set an ultimate speed barrier known as the
lightspeed, many physicians have tried to find out if it's possible to travel
faster than light, without violating relativity.
We know that it's impossible to keep on accelerating forever. How closer we get
to lightspeed, how heavier we become. And not to forget time dilatation: the
effect of time slowing down.
However, there are ways to break the lightspeed barrier. We will look at the
physics and possible technical realization of 9 concepts.

CONTENTS OF PART I:

1. Making space into waves, and travel through the waves
2. Bringing points in space closer together
3. Changing the speed of light around your ship
4. Reduce the ships mass to 0
5. Travelling through wormholes
6. Entering subspace
7. Star Trek warp drive
8. Emit or store tachyons
9. Compressing and expanding spacetime

1. Making space into waves

We want to travel from A to B:

A B


Then a special modulated gravity emitter pulls space time into waves:
/\ /\ /\
/ \ / \ / \
/ \ / \ / \
/ \ / \ / \
/ \ / \ / \
/ \ / \ / \
A-------------------------------------------------B
__/ \/ \/ \__

By travelling in a straight line, between the waves, the distance is much
shorter.
Our absolute speed is not necessarily higher than light speed, but because we
traverse A to B in much shorter time than a beam of light would do, our
effective speed is higher than light.
We traverse the waves by building wormholes.
Can this drive be realized? We need enormous amounts of energy to make spacetime
into waves, and to build wormholes. Antimatter-reactors, one of the greatest
known potential energy sources, might provide too less energy. If we can find
an energy source which provides much and much more of energy, then it might.

2. Bringing points in space closer together

This is very easy. If the distance between two points becomes smaller, then we
can travel from point A to B in a conventional sub-lightspeed drive. There is
no need for a direct FTL drive.
We bring this points together just like concept 1: we emit massive amounts of
gravity. But here do we encounter the same problem: we need an energy source
which can provide a real enormous amount of energy.

3. Changing the speed of light around your ship

We create a bubble of modified spacetime around our ship, in where te physical
laws are changed. With a higher lightspeed barrier, we can travel at a speed
just below that, but maybe higher than light in normal spacetime. To reach
a speed x times less than modified lightspeed c_m needs as much energy than
achieve a speed x times less than normal lightspeed c_n. Did you grab that?
But we don't know how we must create a bubble of modified spacetime. However,
one thing is for sure: we need lots and lots of energy.

4. Reduce the ship's mass to 0

This concept cannot achieve FTL speeds. The speed of an object with zero mass
is still restricted to lightspeed. Another problem: massless objects ALWAYS
travel at lightspeed, except in a dense medium.
If we want to achieve lightspeed, this concept is well. We only need to
eliminating gravity, and that isn't necessarily difficult. We can emit some
kind of antigravity, if we find a way how.
But we want to break the lightspeed barrier.

5. Travelling through wormholes

This is a well known concept. Wormholes can make a long travel a lot shorter,
because they make the distance shorter:
________ ________
\ A o===================o B /
\ \ \ wormhole / / /
\ \ \ / / / - bent space time
\ \ \ / / /
\ \ \ / / /
\ \ \_____/ / /
\ \ / \ / /
\ \_______/ /
\ / \ /
\/___________\/

The bent spacetime as shown here, can be considered as our galaxy; our galaxy
influents the spacetime continuum in the same way as shown above.

To travel through wormholes, we need one at a macroscopic level. Quantum
mechanics predicts wormholes, but quantumwormholes will seldomly be greater
than 10E-33 cm. We can track a quantumwormhole, and blow it up to macroscopic
size. But macroscopic wormholes are instable - they will collapse because of
their own gravitational forces. However, if we continually feed a macrowormhole
with some kind of negative energy, a macrowormhole will be stable.
Until this far, this concept is very promising. But there are still some
problems: we can't predict where a wormhole will end. And it is also possible
that travelling through a wormhole will take you back in time, causing causality
paradoxes.
And if we can predict where wormholes will end, and if we even know how to
create a wormhole to the place where we want to be, we need still very huge
amounts of energy, just like the FTL concepts above.

6. Entering subspace

Subspace is a hypothetical continuum, which encloses our entire universe. It
has different laws than ours. In Star Trek, travelling through subspace doesn't
restrict you to light speed: in subspace, you can go any speed.
But there are two problems:
1) Does subspace exists?
2) And if yes, how must we enter and leave it?
We don't know the answers.

7. Star Trek warp drive

The Star Trek warp drive is discussed a lot in the world of physics. The
designers of warp drive have made complete building schedules.
It's powered by a tuned plasma stream from an matter/antimatter reactor.
Injectors feed the plasma into coils at specific times, causing pulses to run
the length of the nacelles, front to back. This peristaltic flow should cause
the push of nested subspace fields, and moves the ship forward.
The Star Trek Technical Manual says that the fields couple and decouple from
each other at velocities near (but less than) c. It could be that the
interaction of these fields, combined with the special frame subspace provides,
causes the ship as a whole to travel at FTL speeds.
But we have again energy problems. Without a constant influx of energy, the
subspace field will decay, and the ship will drop out of warp. In other words,
you must continue to provide energy to maintain your warp velocity.
The designers of warp drive use matter/antimatter reactors to provide that
energy. If that's enough, we don't know, but we also don't know if subspace
even exists.
Maximum warp speeds in Star Trek are approx. 7000c.

8. Emit or store tachyons

Tachyons are hypothetical particles which travel billions of times faster than
light. Their mass is negative or imaginary (an imaginary number is the result
of the square of a negative number), which allows them to go travel faster
than light, with a lower limit of c. In other words, they can travel any speed,
but never slower than light (more physical information about tachyons, see my
Encyclopedia: encyc.htm).
If we emit tachyons, we need relatively low amounts of fuel for a large speed.
If we will travel faster than light, that is not known.
If we store enough tachyons, our ship's mass will decrease, and if it's lowered
to negative or imaginary proportions, we will travel faster than light with
the same mechanism as tachyons do. To slow down, we just need to dump the
tachyons, so we will drop out of super-lightspeed.

9. Compressing and expanding spacetime

This concept is proposed by physician Miguel Alcubierre. He calls it, just
like the FTL drive in Star Trek, the 'warp drive'.
At the front of the ship, spacetime is pulled towards the ship. At the back
of the ship, spacetime is expanded. The ship doesn't even needs to move.

-------> [SHIP] ------->
spacetime is pulled spacetime is expanded

In fact, spacetime moves, not the ship.
Just like all the other concepts, we need a lot of energy. Miguel Alcubierre
proposes the use of a sort of 'exotic matter', which influents spacetime.

------------------------------------------------------------------------------

PART II: ENERGY SOURCES

It is clear that we need very high amounts of energy to travel at FTL. Some
say that this point makes FTL travel impossible. But is that true? Many people
think that we'll find an suitable energy source.
In this part, we'll look at x energy sources.


CONTENTS OF PART II:

10. Matter/antimatter reaction
11. Nuclear fusion
12. Zero-point energy
13. Singularities
14. Matter-energy conversion

------------------------------------------------------------------------------


10. Matter/antimatter reaction

This energy source is based on controlled annihilation of matter and antimatter.
It is used in Star Trek as energy source for warp drive.
If you annihilate 1 gram per second, you get an energy at least equal to the
present worldwide energy production in one year. If that's enough, is not
known.
Some sub-lightspeed starship designs with matter/antimatter propulsion are
based on speeds between 30,000 and 300,000 km/s (lightspeed). However, this
engines are based on emission of the gamma radiation produced by annihilation
reactions and not as energy source for another drive.

11. Nuclear fusion

Controlled nuclear fusion of light atoms to heavier atoms. In stars is hydrogen
fused to helium, and helium to heavier elements. Nuclear fusion is just like
matter/antimatter reaction often proposed as energy source for travelling at
faster than, or just less than, lightspeed.
It's known that nuclear fusion produces less energy as matter/antimatter
reactions Thus, it's not a very serious candidate.


12. Zero-point energy

This is a new discovery and a very promising candidate. Zero-point energy is
an energy that's stored in the whole universe (in other words: it's everywhere),
and is released when the temparature is dropped to -273,16 degrees Celcius
(0 degrees Kelvin), the absolute zero-point. In experiments are little bits
of zero-point energy released, at temparatures a little bit above the absolute
zero-point.

13. Singularities

The use of artificial singularities, or miniature black holes, is often seen
in Star Trek. It is based on releasing energy from an artificial black hole
in the central energy core. In Star Trek: Voyager, we saw that an artificial
singularity produces an constant energy flux of 5 terawatt.
There's one problem: the gravity of a singularity is so strong, that the ship
should collaps by it.

14. Matter-energy conversion

Based on the E=mc^2 formula of Einstein, which says that the mass of an object
is equivalent to energy. If we find a way to convert mass to direct mass-energy,
we have found a very huge energy source. This is best shown if we say that
a black hole emits only 30% (at highest, 60%) of the mass-energy of an object
thrown in the black hole. Black holes are not very good mass-energy releasers.
A matter-energy converter is more than 3 times more efficient as a black hole.

PART III: CONCLUSION

I think it is possible that we can travel at FTL speeds in the future. Tachyon
emission/storage is the most promising concept. If we find a way to 'catch' or
produce tachyons artificially, tachyon drive should be invented in a matter of
a few years.
My prediction? It's hard to say when humanity will explore the galaxy in FTL
driven ships, but I think that FTL drive should be realized in two centuries.
In Star Trek: First Contact we saw that dr. Zephrem Cochrane invented warp
drive in 2063. I hope that FTL travel will come as fast as that.

Answer 2

In simple terms. As a body accelerates it needs more energy to keep the acceleration going. So, a car going from 0 to 20 needs less energy then going from 20 to 40. This is due to an increase in mass. The greater the speed, the more energy required to accelerate. As the speed approaches the speed of light, mass approaches the infinite. So, the energy required to accelerate approaches the infinite. This means all the energy in the universe cannot accelerate a body to the speed of light. This, of course, only applies to a massive body (i.e. a body that has an inherent mass).

Answer 3

Think of it this way... as you near the speed of light, your mass increases - on it's way to infinity.

No rocket engine, no matter how much fuel you have or can supply, can push an infinite mass the little extra amount to from .99999C to the actual speed of light. Your mass - even if you're a *feather* - increases to infinity as you near the speed of light.

Now... E=MC^2 really isn't about speed & mass, it's about Energy & mass. So... if you could take a little amount of mass, and turn it into energy - you get a lot of it. Think of the atom bombs we dropped on Hiroshima & Nagasaki to end World War 2. A *very small amount* of mass was converted into energy - less than an ounce in each case. While the bomb itself weighed 10 tons, only 15 pounds of that was the actual core - and of that, only about 0.05 of that mass was converted into energy. So - the mass that was 'converted', times the speed of light squared (that's 186,282 miles a second), is equal to the Energy released.

On the other side of the coin, it's *conceivable* to take a vast amount of energy, in some form - and convert it into matter. But we haven't quite gotten that far yet.

Answer 4

The mc squared formula doesn't enter in. It's contained in a thing called a Lorentz transformation which says that you can't reach the speed of light because your mass will appear to be infinite.To need an infinite amount of energy to get there if you have a rest mass.

Answer 5

I am afraid to really explain it is PhD material. The basic idea is that light appears to go the same speed for all observers. This means that the light from headlights of a car driving at half light speed is seen by the driver leaving his car at light speed, which is to be expected, but a person sitting still behind the car sees the car moving away at half light speed and the light from the car's headlights moving away at light speed, not one and a half times light speed. The stationary person would assume that the driver sees his own headlight's light moving away at half light speed, but it isn't so.

Now relativity does not predict this behavior, it explains it. The behavior itself is observed experimentally. In other words we SEE light doing this and relativity is just a complex mathematical system to explain it. Relativity changes time and distance with speed, so that speed, which is distance divided by time, is always the same for light. When I say always the same, I mean the same even when common sense says it should be different. It would be like saying that when you drive 60 to pass a car driving 30, you see yourself passing the car at 60. It doesn't add up. But relativity MAKES it add up, by changing the rules for addition. Kind of.

None of this requires keeping E=MC^2 in mind.

For more detail, see the source.

Answer 6

When dealing with anything approaching the speed of light, classical (Newtonian) mechanics fail to approximate reality. In general, all calculations need to have the "gamma" value (1 / sqrt(1 - v^2/c^2)) multiplied into them.

Under Newtonian physics, F = ma (force = mass * acceleration), and P = m * v (power = mass * velocity). Under relativistic physics, which is what we need to use as we approach the speed of light, P = m * v * gamma.

Note that in the equation for gamma listed above, as your speed approaches the speed of light, gamma gets bigger and bigger (towards infinity, when v = c). Thus, as your speed increases, the amount of power required to go just a little bit faster tends toward infinity, and of course, it's impossible to get such infinite power.

Answer 7

The formula E=mcsquared means that Energy is directly proportional to mass and the speed of light. Since the speed of light is very high, you will also need very high amount of energy to reach that speed. For example even if your weight is just 2kilograms (approximately the weight of a baby), you'll need around the energy equal to millions of nuclear bomb exoploding to reach the velocity of light. That is how much energy you'll need and it is impossible to gather that much energy just to propell someone who just weighs like new born baby. I think that answers why is it impossible.

Answer 8

The faster something goes, the more energy it will take for it to go faster. When the speed of light is approached, the object being pushed will have to overcome its own weight to increase its speed. Remember that it takes the power of the sun to push photons the speed of light to produce light. Photons don't even have weight and it takes the power of the sun to push them that fast. If you have a spaceship, even a light one, you'd need an engine duplicating the sun's power for every electron, every proton, even every neutron that the ship is made up of to push it up to light speed. That kind of power is impossible to produce.
Then again, it used to be impossible to go 60 miles per hour. Then it was impossible to go the speed of sound. Who knows what impossibilities will be overcome in the next 100 years!

Answer 9

There is a resistance that increases rapidly as one nears light velocity. An object gains mass as it accelerates. If it could go at light velocity, it would have infinite mass. Not all the matter in the universe could accelerate a material object to that velocity.

Answer 10

"Energy equals mass times the velocity of light squared." So what exactly does the velocity of light have to do with it?
By far, Einstein's best-known equation is "E=mc2 - energy equals mass times the velocity of light squared." According to this equation, any given amount of mass is equivalent to a certain amount of energy, and vice versa.

We all have some idea of what mass and energy are, and can appreciate that either can be converted into the other. Einstein's equation even tells us how much of one potentially converts into how much of the other. But what exactly does the speed of light have to do with either matter or energy? How does the speed of light, of all things, come into the picture at all?

The answer turns out to be one of the easiest to follow of all Einstein's derivations. When Einstein derived the relation of mass to energy, he had already demonstrated how time is a direction much like the directions of space, and how the distance and time intervals between events depend on one's frame of reference, which changes as one changes velocity. He also found that other things depend on one's frame of reference in a similar manner, such as the strengths of electric and magnetic force fields. The way electric and magnetic fields depend on frames of reference gave Einstein a road to what he called "a very interesting conclusion."

We can follow Einstein's road by considering a simple physical situation. Suppose we have an object of some kind that can emit energy. The kind of energy it emits doesn't matter. The object could be a cup of hot chocolate that heats up the surrounding air. Or it could be something that can radiate energy in the form of sound, like a telephone, an alarm clock, or a radio. To keep the situation simple, as Einstein did, we will stipulate that in our own frame of reference the object is stationary. For the object to remain stationary throughout the process, it will need to emit the energy evenly in different directions; otherwise, the object would move as it recoils away from the direction most of the energy would be going.

To keep things even simpler we'll further specify, again like Einstein, that the object always emits the same amount of energy at the same time in exactly opposite directions. Furthermore, we will assume that the object emits the energy in a finite amount of time. Then we can consider what happens before and after the energy is emitted, without being concerned with what happens during the process itself.

Since natural processes only change the form of energy without changing the total amount, the energy the object has before it emits any is equal to the energy it has afterward, plus the amount it emits.

object's energy before = object's energy after + emitted energy

That's the situation as we see it from our own reference frame. The situation in any other reference frame differs only in the amounts of energy involved: the energy of an object is greater when it is moving that when it is stationary, and anyone moving past us will see the object as moving past them. But even in other frames of reference, the law of energy conservation still holds - total energy before equals total energy after.

We can summarize the energy situation in both reference frames with two simple equations, one for the moving observer (m.o.) and one for us, the stationary observers (s.o.):

object's energy before (m.o.) = object's energy after (m.o.) + emitted energy (m.o.)

object's energy before (s.o.) = object's energy after (s.o.) + emitted energy (s.o.)

As we just mentioned, the energy of an object that's moving in one reference frame is greater than the energy of the same object in a different reference frame in which it is stationary. The same energy difference exists when the object goes from moving to being stationary in any single frame of reference. This difference is called the object's kinetic energy, or energy of motion. If we subtract everything in the equation just above from the corresponding items in the equation just before it, we will find what the moving observer sees as the kinetic energy of our object, both before and after it emits energy:

object's energy before (m.o.) - object's energy before (s.o.)

= object's energy after (m.o.) - object's energy after (s.o.)

+ emitted energy (m.o.) - emitted energy (s.o.).

Put another way,

object's kinetic energy before (m.o.)

= object's kinetic energy after (m.o.)

+ emitted energy (m.o.) - emitted energy (s.o.).

The only energy difference we haven't figured out at this point is the difference between the energy emitted as seen in the other observer's reference frame and as seen in ours.

It is at this point that Einstein's earlier discovery about how electric and magnetic fields are different in different reference frames gave him a road to his interesting conclusion. Einstein realized that the form in which the object emits energy is not important. It could be sound, it could be heat, it could be something else, but whatever form it is, the change that the moving observer sees in the object's kinetic energy will equal the difference between the energy that he sees the object emitting and the energy we see it emitting.

What Einstein did was to consider emission of electromagnetic energy, which he had already figured out how to calculate for two different frames of reference. In particular, he considered energy in the form of light, which is a type of electromagnetic force field. So instead of a cup of hot liquid heating its surroundings, or a bell making a sound, we can imagine a light bulb shining equally in all directions in our reference frame. In this case, if the emitted light has (to us) an energy L:

emitted energy (s.o.) = L

the emitted light has, to the moving observer, a higher energy:

emitted energy (m.o.) = ,

which is times greater than L. The "v" stands for the velocity of our moving observer (or the velocity that he sees the object moving), and the "c" stands for the speed at which light travels in a vacuum.

When we use these expressions for the emitted energy in the equation preceding them, we find the change that our moving observer sees in the object's kinetic energy:

object's kinetic energy before (m.o.)

= object's kinetic energy after (m.o.)
+ - L.



Two more facts and we are there.

First, as long as the velocity of our moving observer is not very large compared to the speed of light in a vacuum (our usual experience), the difference between the emitted energy as seen by us and the moving observer is approximately

½ (L/c2) v2.

Second, under those same conditions, the kinetic energy of a moving object is approximately

½ (mass of the object) v2.

Since the velocity of the object as seen by the moving observer, "v", is the same after it emits the energy as it was before, the only way its kinetic energy can change is if its mass changes. Evidently, the mass changes by L/c2 - by the energy the object emits (in our frame of reference), divided by the speed of light in a vacuum squared. Since, as Einstein pointed out, the fact that the energy taken from the object turns into light doesn't seem to make any difference, he concluded that whenever an object emits an amount of energy L of any type, its mass diminishes by L/c2, so that the mass of an object is a measure of how much energy it contains.

If we go back to Einstein's first paper on relativity, we find that the speed "c" is involved, not because we considered light instead of some other energy form, but because "c" is the speed at which time becomes, in a sense, equivalent to space, as the preceding article in this series illustrates. The fact that "c" is also the speed of light in a vacuum is coincidental. We would have found the same relation between mass and energy even if we had considered energy emitted in a form other than light, although it might have made the math more difficult.

Interestingly enough, Einstein first expressed his conclusion in about the same way above, without actually using the equation "E=mc2". He only expressed the result that way later on. i know it didn't stay simple but the first bit you can follow and the second bit ignore or keep in mind for latter