Before beginning this brief article, dealing with the essential features of General Relativity, we have to postulate one thing: Special Relativity is supposed to be true. Hence, General Relativity lies on Special Relativity. If the latter were proved to be false, the whole edifice would collapse. In order to understand General Relativity, we have to define how mass is defined in classical mechanics. The Two Different Manifestations of Mass: First, let’s consider what represents mass in everyday life: “It’s weight.” In fact, we think of mass as something we can weigh, as that’s how we measure it: We put the object whose mass is to be measured on a balance. What’s the property of mass we use by doing this? The fact that the object and Earth attract each other. To be convinced of it, just go in your garage and try to raise your car! This kind of mass is called “gravitational mass.” We call it “gravitational” because it determines the motion of every planet or of every star in the universe: Earth’s and Sun’s gravitational mass compels Earth to have a nearly circular motion around the latter. Now, try to push your car on a plane surface. You cannot deny that your car resists very strongly to the acceleration you try to give it. It is because the car has a very large mass. It is easier to move a light object than a heavy one. Mass can also be defined in another way: “It resists acceleration.” This kind of mass is called “inertial mass.” We thus arrive at this conclusion: We can measure mass in two different ways. Either we weigh it (very easy...) or we measure its resistance to acceleration (using Newton’s law). Many experiments have been done to measure the inertial and gravitational mass of the same object. All lead to the same conclusion: The inertial mass equals the gravitational mass. Newton himself realized that the equality of the two masses was something his theory couldn’t explain. But he considered this result as a simple coincidence. On the contrary, Einstein found that there lay in this equality a way to supplant Newton’s theory. Everyday experimentation verifies this equality: Two objects (one heavy and the other one light) “fall” at the same speed. Yet, the heavy object is more attracted by Earth than the light one. So, why doesn’t it fall “faster?” Because its resistance to acceleration is stronger. From this, we conclude that the acceleration of an object in a gravitational field doesn’t depend upon its mass. Galileo Galilei was the first one to notice this fact. It is important that you should understand that the fact that all objects “fall at the same speed” in a gravitational field is a direct consequence of the equality of inertial and gravitational masses (in classical mechanics). Now, I would like to focus on the expression “to fall.” The object “falls” because of Earth’s gravitational field generated by Earth’s gravitational mass. The motion of the two objects would be the same in every gravitational field, be it Moon’s or Sun’s. They accelerate at the same rate. It means that their speeds increase by the same value in every second (Acceleration is the value by which speeds increases in one second). The Equality of Gravitational and Inertial Masses as an Argument for Einstein’s Third Postulate: Einstein was looking for something which could explain this: “Gravitational mass equals inertial mass.” Aiming at this, he stated his third postulate, known as the principle of equivalence. It says that if a frame is uniformly accelerated relative to a Galilean one, then we can consider it to be at rest by introducing the presence of uniform gravitational field relative to it. Let’s consider a frame K', which has a uniformly accelerated motion relative to K, a Galilean frame. There are many objects around K and K'. These objects are at rest, relative to K. So, these objects, relative to K', have a uniformly accelerated motion. This acceleration is the same for all objects, and it is opposed to the acceleration of K' relative to K. We have just said that all objects accelerate at the same rate in a gravitational field. So, the effect is the same as if K' is at rest and that a uniform gravitational field is present. Thus, if we state the principle of equivalence, the equality of the two masses is a simple consequence of it. That’s why this equality is a powerful argument in favor of the principle of equivalence. By supposing K' is at rest and a gravitational field is present, we make of K' a Galilean frame, where we can study the laws of mechanics. That’s why Einstein stated his fourth principle: Einstein’s Fourth Postulate: Einstein’s fourth postulate is a generalization of the first one. It can be expressed in the following way: “The laws of nature are the same in every frame.” It cannot be denied that it is more “natural” to say that the laws of nature are the same in every frame than in Galilean ones. Moreover, we don’t really know if a Galilean frame really exists. This principle is called the “Principle of General Relativity.”
As the mass of energy is very small (c^{2} = {300,000,000 meters/sec}^{2}!), the phenomenon can only be detected in the presence of VERY strong gravitational fields. It has been verified thanks to the Sun’s great mass: rays of light are curved when they approach it. This experiment was the first confirmation of Einstein’s theory. All these experiments allow us to conclude: We can consider that an accelerated frame is a Galilean one by introducing the presence of a gravitational field. Furthermore, it is true for all kinds of motions, be they rotations (the gravitational field explains the presence of centrifugal forces) or not uniformly accelerated motions (which is translated mathematically by the fact that the field doesn’t satisfy Riemann’s condition). As you see, the principle of General Relativity is fully in accordance with experience! Figure 4: 
Angle θ Degrees 
Measured Velocity = v = (c)(sinθ) v/c = sinθ 
Distance (Length) Contraction or Time Dilation Factor = cosθ = [1 – (v/c)^{2}]^{1/2} 
SpaceTime Compression Factor = γ = 1/cosθ = secθ = 1/[1 – (v/c)^{2}]^{1/2} 
Effective Velocity = v_{eff} = (c)(tanθ) = (c)(sinθ/cosθ) [v_{eff}/c] = tanθ 

0.000  0.000  1.000  1.000  0.000 
2.866  0.050  0.999  1.001  0.050 
5.739  0.100  0.995  1.005  0.101 
8.627  0.150  0.989  1.011  0.152 
11.537  0.200  0.980  1.021  0.204 
14.478  0.250  0.968  1.033  0.258 
17.458  0.300  0.954  1.048  0.314 
20.487  0.350  0.937  1.068  0.374 
23.578  0.400  0.917  1.091  0.436 
26.744  0.450  0.893  1.120  0.504 
30.000  0.500  0.866  1.155  0.577 
33.367  0.550  0.835  1.197  0.659 
36.870  0.600  0.800  1.250  0.750 
40.542  0.650  0.760  1.316  0.855 
44.427  0.700  0.714  1.400  0.980 
45.000  0.707  0.707  1.414  1.000 
48.590  0.750  0.661  1.512  1.134 
53.130  0.800  0.600  1.667  1.333 
58.212  0.850  0.527  1.898  1.614 
60.000  0.866  0.500  2.000  1.732 
64.158  0.900  0.436  2.294  2.065 
71.805  0.950  0.312  3.203  3.042 
73.739  0.960  0.280  3.571  3.428 
75.930  0.970  0.243  4.113  3.990 
78.522  0.980  0.199  5.025  4.925 
81.890  0.990  0.141  7.470  7.018 
84.268  0.995  0.100  10.013  9.962 
85.000  0.996  0.087  11.474  11.430 
85.561  0.997  0.077  12.920  12.882 
86.376  0.998  0.063  15.819  15.789 
87.437  0.999  0.045  22.366  22.340 
As indicated in Table 1, above, measured velocities do not contribute significantly to the “SpaceTime Compression” effect unless the measured velocity is a significant fraction of the the velocity of light, c. At a measured velocity of 0.995c, the “SpaceTime Compression Factor” is just above 10 and at a measured velocity of 0.999c, the “SpaceTime Compression Factor” is just under 22.4.
Table 1 introduces the concept of effective velocity. When the spacecraft is traveling at a measured velocity of 0.707c, the effective velocity, v_{eff}, of the spacecraft is 1.000c or the speed of light, c. Although the spacecraft only has a measured velocity as 0.707c, the length contraction along the line of travel is reduced to 0.707 (or 70.7%) of the original distance (which represents a “SpaceTime Compression Factor” equal to 1.414), therefore, the time to travel the uncompressed distance (which is a known quantity) is equal to the time it would take light to travel the uncompressed distance.
EXAMPLE:
Let’s assume our astronaut is traveling from the Earth to a star system 10 lightyears distant. The astronaut is traveling at a measured velocity of 0.707c. The astronaut measures the distance to the star system as only 7.07 lightyears rather than 10 lightyears because of the relativistic length contraction in the direction of motion. The astronaut’s travel time to the star system is 10 years as measured by the astronaut. The observer on Earth watching the astronaut accomplish the trip disagrees on the time elapsed. The observer on earth agrees with the astronaut that the astronaut’s measured velocity is 0.707c. However, the observer on Earth measures the distance the astronaut must travel as 10 lightyears (the Uncompressed SpaceTime distance). The observer on Earth measures the time elapsed for the astronaut to accomplish the trip from Earth to the star system as 14.1 years. Realize that it takes time for the light to travel from our astronaut’s position back to earth resulting in the disagreement on the time required for the astronaut to make the trip.
If a person could, theoretically, accelerate to the actual measured velocity of light, c, then the distance required to be traveled would be compressed to zero length. In this case, the effective velocity, v_{eff} would be infinity and zero time would be required to travel the distance because the distance is now zero. With measured velocities very close to that of the speed of light, c, the effective velocity, v_{eff} approaches the SpaceTime Compression Factor. Therefore, because of the “SpaceTime Compression” phenomenon, one could effectively travel much faster than the speed of light. The relationship between measured velocity, v, effective velocity, v_{eff}, and “SpaceTime Compression Factor” is defined by the relationship of the various trigonometric functions.
Let’s look at SpaceTime Compression in two hypothetical relativistic inertial reference frames. Consider an observer on Earth looking at a star 10 lightyears distant and an observer on a spacecraft traveling at a velocity, v = 0.98c, which is a significant fraction of the velocity of light, c. The light propagating from the star is measured to be moving at a velocity of c by both the observer on Earth and the observer in the spacecraft traveling at 0.98c. Recall that the velocity of light will always be measured the same in a vacuum, no matter what inertial reference frame the observer is in. We cannot add the velocity of our spacecraft to the velocity of light and get a result for the velocity of light other than c because the speed of photon propagation in a vacuum will always be measured as c no matter what reference frame one exists in when measuring the speed of light. Therefore, “v + c = c.” This “strange math” works out because we are adding velocities. A velocity is defined as a change in position of an object or particle with respect to some measured elapsed time. The “strange math” occurs because the measured elapsed time is different for observers in different inertial reference frames. We will compare what each observer sees at the instant the observer in the spacecraft passes by the Earth and the observer on the Earth. The observer in the spacecraft and the observer on Earth disagree on the distance to the star and the amount of time it takes light to travel from the star to each of them. The observer on Earth measures the distance as 10 lightyears. The observer in the spacecraft, however, measures the distance to the star to be about 2 lightyears because the SpaceTime Compression factor for traveling at 0.98c is equal to 5.025 resulting in his/her observed length contraction. In addition, because of the shorter measured distance, the time it takes the light to travel from the star to the observer on the spacecraft is only about 2 years because of the length contraction. To the observer on Earth, it appears to take the spacecraft over 10 years to arrive at the star. The disagreement between the observer in the spacecraft and the Earth observer for the time it takes the spacecraft to travel the distance to the star occurs because of the delay time for the light from the spacecraft to return back to Earth. If the spacecraft is 10 lightyears away, it will take 10 years for the light from the spacecraft to reach Earth. This hypothetical scenario demonstrates the equivalence of space (distance) and time.
One other concept that is observed here is that of “effective velocity.” The “effective velocity” represents the velocity of the spacecraft relative to Normal SpaceTime rather than Compressed SpaceTime. This would be the case if the velocity of light was infinite. The observer in the spacecraft realizes that the normal spacetime distance to the star is 10 lightyears even though, with the spacecraft measured velocity of 0.98c relative to Earth, the Compressed SpaceTime distance measured to the star is 2 lightyears. Therefore the effective velocity of the spacecraft is about 5 times the speed of light because it takes the observer 2 years, as measured by spacecraft onboard clock, to travel the Normal SpaceTime distance of 10 lightyears to the star. If the spacecraft was traveling at 0.7071c to the star 10 lightyears away, the measured Compressed SpaceTime distance to the star would be 7.071 lightyears. The time it would take the spacecraft to travel the Compressed SpaceTime distance of 7.071 lightyears would be 10 years, as measured by the spacecraft onboard clock. Therefore the effective velocity of the spacecraft is equal to the speed of light. The observer on Earth, however, would measure the time elapsed for the spacecraft to travel the actual 10 lightyear distance to the star as 14.142 years. That time is consistent with the measured velocity of the spacecraft relative to the Earth observer of 0.7071c. The additional 4.142 years that elapses for the spacecraft trip, as measured by the observer on Earth, results from the fact that it takes time for the light to return to Earth from the spacecraft, as the spacecraft travels to the star. From the right triangle and Pythagorean Theorem, one can see that sin θ represents the measured velocity of the spacecraft and tan θ represents the effective velocity of the spacecraft. If the spacecraft could have an actual velocity of the speed of light (sin θ = 1), then the effective velocity would be infinity (tan θ = infinity). Spacetime would be compressed to zero length based upon traveling at the speed of light.
Let’s look at the Flying Disc Spacecraft traveling at 0.98c relative to Earth as it passes over an Aircraft Hanger on the Earth from left to right. We will examine what an observer in front of the Aircraft Hanger on Earth at rest relative to the Aircraft Hanger would see as the Flying Disc Spacecraft passes above the Aircraft Hanger. We will compare that observation to what an observer in a second spacecraft flying in the same direction as the Flying Disc Spacecraft at a velocity of 0.98c such that the Flying Disc Spacecraft appears to be at rest relative to this second observer. Figure 8, below, displays the Flying Disc Spacecraft hovering over the Aircraft Hanger such that the Flying Disc Spacecraft is “at rest” relative to the Aircraft Hanger. The Flying Disc Spacecraft is 300 feet in diameter and the Aircraft Hanger is 300 feet in width from left to right. Therefore when both the Flying Disc Spacecraft and the Aircraft Hanger are at rest relative to each other, they appear to be the same width.
First we will analyze what the observer on Earth in front of the Aircraft Hanger sees as the Flying Disc Spacecraft passes over the Aircraft Hanger. As the Flying Disc Spacecraft passes over the Aircraft Hanger, we will focus on four specific events noted by the observer on Earth. Refer to Figure 9, below:
Note in Figure 9, above, that the Flying Disc Spacecraft is “compressed” by a factor of 5 in width along its direction of motion. This represents the “SpaceTime Compression” in the direction of motion of the Flying Disc Spacecraft as seen by the observer on Earth because its velocity relative to the observer on Earth is 0.98c (See Table 1, above). The events of interest as seen by the observer on Earth in front of the Aircraft Hanger as the Flying Disc Spacecraft passes over the Aircraft Hanger from left to right are as follows in order of the occurrence of each of those events.
Event 1:  The leading edge of the Flying Disc Spacecraft aligns with the left side of the Aircraft Hanger. 
Event 2:  The lagging edge of the Flying Disc Spacecraft aligns with the left side of the Aircraft Hanger. 
Event 3:  The leading edge of the Flying Disc Spacecraft aligns with the right side of the Aircraft Hanger. 
Event 4:  The lagging edge of the Flying Disc Spacecraft aligns with the right side of the Aircraft Hanger. 
Now we will analyze what the observer on the second spacecraft flying with the Flying Disc Spacecraft at 0.98c relative to Earth and the Aircraft Hanger sees as the Flying Disc Spacecraft passes over the Aircraft Hanger. Just as with the observer at rest on Earth in front of the Aircraft Hanger, above, we will focus on four specific events as the Flying Disc Spacecraft passes over the Aircraft Hanger. However, the events will be noted as seen by the observer in the second spacecraft. Refer to Figure 10, below:
Now note in Figure 10, above, that the Aircraft Hanger, rather than the Flying Disc Spacecraft, has a “compressed” width along the direction of motion of the Flying Disc Spacecraft. The Flying Disc Spacecraft appears to have full width. This represents the “SpaceTime Compression” in the direction of motion of the Flying Disc Spacecraft as seen by the second observer in the observing from the second spacecraft. Because the second spacecraft is flying with the Flying Disc Spacecraft, the Flying Disc Spacecraft appears to be at rest relative to the second spacecraft, hence, appears to be of full width in the direction of motion. The Earth and the Aircraft Hanger appear to be moving at a velocity of 0.98c from right to left relative to both the spacecraft in motion resulting in the Aircraft Hanger appearing to be “compressed” in width by a factor of 5 along the direction of motion of the Flying Disc Spacecraft (see Table 1, above). The events of interest as seen by the observer in the second spacecraft as the Flying Disc Spacecraft passes over the Aircraft Hanger from left to right are as follows in order of the occurrence of each of those events.
Event 1:  The leading edge of the Flying Disc Spacecraft aligns with the left side of the Aircraft Hanger. 
Event 2:  The leading edge of the Flying Disc Spacecraft aligns with the right side of the Aircraft Hanger. 
Event 3:  The lagging edge of the Flying Disc Spacecraft aligns with the left side of the Aircraft Hanger. 
Event 4:  The lagging edge of the Flying Disc Spacecraft aligns with the right side of the Aircraft Hanger. 
There is an obvious disparity between the observations of the two observers. The first observer is on Earth at rest relative to the aircraft hanger and the second observer is onboard a second spacecraft moving at a velocity of 0.98c in parallel with the Flying Disc Spacecraft, therefore, at rest relative to the Flying Disc Spacecraft. The two observers disagree with the order of the events taking place as the Flying Disc Spacecraft flies over the aircraft hanger. The event the Earth observer identifies as “Event 2” is identified as “Event 3” by the observer on the second spacecraft. Likewise, the event the Earth observer identifies as “Event 3” is identified as “Event 2” by the observer on the second spacecraft. Although the time interval between “Event 2” and “Event 3” is on the order of only 300 nanoseconds (300 x 10^{–9} seconds), there is a reversal of the order of the events in SpaceTime. This hypothetical situation demonstrates that the times of occurrence of events are relative to the specific reference frames of the observers and are not absolutes. Observers in different reference frames will not agree on the order of events, nor will they agree on the simultaneity of events. This disagreement in the order of events in time provides the evidence that timetravel is, theoretically, possible. If the SpaceTime Compression factor is large enough, then events that are years apart could be reversed relative to observers in different reference frames. Large SpaceTime Compression factors could, theoretically, be generated by amplifying gravity in a local area to generate separate accelerated reference frames (see the following discussion on accelerated reference frames). The “The Philadelphia Experiment and the Secrets of Montauk” Website provides testimony from several individuals regarding their involvement with the U.S. Government’s Top Secret timetravel experiments. It has been speculated that Albert Einstein and John Von Neumann were both involved with the Philadelphia Experiment. It has been speculated that John Von Neumann was intimately involved with the Phoenix Project, also known as the Montauk Project.
Accelerated Reference Frames:
When “generalized” to include the effects of gravity, the equations of relativity predict that gravity, or the curvature of SpaceTime by matter, not only stretches or shrinks distances (depending on their direction with respect to the gravitational field) but also will appear to slow down or “dilate” the flow of time  the very definition of SpaceTime Compression. The equations used to represent the curvature of SpaceTime in gravitational fields are multidimensional, rather complicated, and dependent upon the geometry of the system of interest. In most circumstances throughout the universe the intensity of the local gravitational field at a point in SpaceTime is relatively small, hence, any SpaceTime Compression taking place in that locality is miniscule. However SpaceTime Compression can become significant at a locality when SpaceTime is curved by a strong gravitational field produced by a massive object such as a star like our Sun as indicated by Figure 11 and Figure 12.  Figure 11: 
Just as the velocity of light in a vacuum will always be measured as c no matter what velocity of travel of the observer, the velocity of light will always be measured as c in an accelerated reference frame, no matter how great the acceleration or gravitational field. Einstein’s General Relativity Theory states that light is accelerated by a gravitational field, which results in the observed “bending of light” around our Sun as indicated by Figure 11, above. This appears to be a paradox. How can light be accelerated, yet remain at a velocity of c? Lets take a look at a rubber ball that is dropped in Earth’s gravitational field as displayed in Figure 13. The ball is initially at rest. When released, the ball begins to fall and its velocity of fall rises as it is accelerated by the local gravitational field of Earth until the rubber ball finally hits the floor. Graphs of the ball fall distance and ball velocity as a function of time are provided in Figure 14 and Figure 15, respectively, below. The graphs assume continual freefall. A photon of light is accelerated by a gravitational field in like manner to our ball falling in Earth’s gravitational field. However, instead of the photon of light traveling faster and faster relative to an external observer as our falling ball does, the distance the photon of light travels (and the time it takes the photon of light to travel that distance) compresses in a manner to offset the acceleration by gravity so that the velocity of the photon of light always remains the same, equal to c, relative to the external observer. This SpaceTime Compression effect is miniscule in Earth’s gravitational field because the gravitational field is relatively weak and the Earth’s average diameter, 7,918 miles, is relatively small compared to the distance light can travel in one second, 186,300 miles or 299,975 kilometers. A photon of light will travel a distance of a bit over 7 circumferences of the Earth in one second (Earth’s circumference is about 25,000 miles). When at or above the Earth’s surface, the Earth’s gravitational field intensity drops off proportional to 1/r^{2} where r represents the distance from the Earth’s center (Newton’s Law of Gravity). Earth’s gravitational field is equal to 1g = 32.2 feet/second^{2} acceleration = 0.00610 miles/second^{2} acceleration at the Earth’s surface, which is just under 4,000 miles from the Earth’s center. At about 4,000 miles above the Earth’s surface, the gravitational field is only 0.25g = 8.05 feet/second^{2} acceleration = 0.00152 miles/second^{2} acceleration. The change in velocity  actually the amount of SpaceTime Compression (photon velocity will always be measured at 186,300 miles/second)  resulting from a photon traveling at 186,300 miles/second spending 1 second in Earth’s gravitational field is very miniscule. A photon of light spends very little time in the Earth’s gravitational field, therefore, is not significantly affected by the Earth’s gravitational field. What we conclude here is the amount of SpaceTime Compression that occurs due to a gravitational field is a function of both the intensity of the gravitational field and the amount of time that a photon of light remains within the gravitational field. Gravitational fields are acceleration fields. The final velocity of an object in an acceleration field is a function of the rate of acceleration in that field and the time that acceleration is applied to an object in the field. An acceleration is a rate of change of velocity as a function of time. 
Figure 13: 

Figure 14: 

Figure 15: 
Let’s consider a photon traveling in the vicinity of the Sun’s gravitational field. The Sun’s diameter is 864,000 miles. The Sun’s gravitational field is about 27.8g = 895 feet/second^{2} acceleration = 0.169 miles/second^{2} acceleration at the Sun’s surface. A photon will travel the Sun’s diameter in 4.64 seconds. A photon of light will be accelerated an additional 0.786 miles/second  SpaceTime will be compressed accordingly to keep the measured velocity of light at 186,300 miles/second. Note that this is a gross calculation because the Sun’s gravitational field is only 27.8g at its surface. The Sun’s gravitational field as measured by an observer moving away from the Sun’s is proportional to 1/r^{2} where r represents the distance of the observer from the center of the Sun. At 864,000 miles above the Sun’s surface, the gravitational field would be 6.95g = 224 feet/second^{2} acceleration = 0.0424 miles/second^{2} acceleration. The Sun’s gravitational field is significant enough and large enough to result in measurable bending of the path of a photon of light.
SpaceTime Compression can become extremely significant when a massive object is compressed into a small volume making the massive object extremely dense such as is the case with a Neutron Star or Black Hole. The gravitational field near the surface of a Neutron Star is on the order of 2.10 x 10^{10}g = 6.76 x 10^{11} feet/second^{2} = 1.28 x 10^{8} miles/second^{2} = 128,000,000 miles/second^{2} acceleration. This rate of acceleration is huge compared to the velocity of light at 186,300 miles/second. Such an intense field will very rapidly accelerate a photon, hence, SpaceTime Compression occurs very rapidly.
Consider a situation where an observer far from a black hole is watching an astronaut in a spacecraft approach the black hole. The observer would witness time passing extremely slowly for an astronaut falling through the black hole’s Schwartschild radius or event horizon. The distant observer would never actually see the hapless astronaut fall into the black hole. The astronaut’s time, as measured by the observer, would appear to stand still.
Therefore, if a relatively intense gravitational field exists in a localized position in SpaceTime relative to an external observer, SpaceTime Compression can be measured without objects traveling at velocities very close to the velocity of light relative to the external observer “at rest.”
What if intense gravitational fields are not limited to massive stars, neutron stars, and black holes? What if we could amplify a gravitational field locally such that we could develop a SpaceTime Compression Factor of 100,000,000. Recall that a velocity of 0.98c yields a SpaceTime Compression Factor of 5.025 and a velocity of 0.999c yields a SpaceTime Compression Factor of 22.366 (See Table 1, above). Such compression factors result in reversing the order of events that are only several nanoseconds apart. In addition, it is very impractical to shift from one reference frame to another when one is moving at a velocity close to that of light in one reference frame relative to the other reference frame. With sufficient gravity amplification to obtain a SpaceTime Compression Factor of 100,000,000, we could potentially reverse the order of events that occur years apart. It appears that gravity amplification could make interstellar space travel possible and time travel possible.
Conclusion:
General Relativity does make our world and universe seem very strange. Consider two stop watches which are calibrated to operate identically. The first stopwatch is placed in a very strong gravitational field and the second stopwatch is placed in a much weaker gravitational field. Both stopwatches are started at precisely the same instant. The first stopwatch will measure time at a slower rate than the second stopwatch. When both stopwatches are stopped at precisely the same instant, the first stopwatch reading is compared to the second stopwatch reading. The first stopwatch indicates that a shorter interval of time has elapsed between the start and stop of the stopwatches than the interval of time that has elapsed as indicated by the second stopwatch. How can two different time intervals be equal (or the same)? Or, how can the same interval of time be different as measured by two identical clocks? General Relativity!
SpaceTime is not linear, it is curved. What appears to be a straight line in space or time may not be because a gravity field is bending the path of light. To an observer, the light path appears to be a straight line. Time appears to be a logical sequence of events. We know that gravity bends or distorts “SpaceTime” and light by virtue of the fact that we’re able to see stars which we know should be blocked from our view by our Sun as indicated by Figure 8, above. We’ve used radio and optical telescopes to map stars and other celestial bodies during the course of our yearly orbit around the Sun, so we know where these celestial bodies should be. When the Sun is between us and a background star, many times we can still see that star as though it were in a different position.
Therefore, the apparent location that one observes an object to be may not be its actual location. Don’t trust your eyes, they may deceive you! Likewise, the order of events in SpaceTime are dependent upon your reference frame. What may be in your past in one reference frame could, very well, be in your future in an alternate reference frame.
I hope you have appreciated this brief introduction to General Relativity. If you have any comments, please EMail the original author, Nymbus, at nymbus@wanadoo.fr or me, Ken Wright, at Info@gravitywarpdrive.com.
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