ATSOL- (Approaching The Speed Of Light)-  The act of accelerating toward the speed of light, getting as close as you can without ever reaching the velocity of C which is 186,287.9 miles/sec.

POTSOL (Percent Of The Speed Of Light), used as most people use the term "miles per hour" when referring to automobiles.   An astronaut traveling at high velocity might refer to his speed as "three tenths POTSOL" or "Zero point three POTSOL".

"C" The unit of measure for light.   1.0 C would be the speed of light.  0.75 C would be three quarters or 75% of the speed of light, where the speed of light is a universal constant at 186,287.9 miles per second.  0.10 C would be 18,628.79 miles per second, or ten percent of the speed of light.

"-C" The representation for speeds below that of light.

"C+" The representation for speeds in excess of that of light.

To put it simply, Alpha Centauri is the closest star system to our own in terms of interstellar distances and crew flight time.  Coincidentally, Alpha Centauri is also the most promising with regard to having the chance of supporting a future colony or of even of having highly evolved life of its own.  We have been studying Alpha Centauri for over fifty years now, and the more data that we collect, the more we are intrigued.  Alpha Centauri is now within our technological grasp to reach, and it is with the criteria that we have judged Alpha Centauri to be a viable interest to both the United States and to the world.  Upon reaching Alpha Centauri, all of our past achievements, even the fact of stepping foot on the moon, will pale in comparison.

Dr. Hasslein, as you approach the speed of light will the universe appear to vanish into a bright point of light ahead of your spacecraft?

As far as we currently understand the effects of near relativistic travel, as an astronaut is looking along their direction of travel, they will see stars directly ahead of them visually move into a strong blue-shift phase.  Looking behind them, they will notice that the stars there have undergone a strong red-shift phase. There will be a ever increasing distortion of where the images are in the perceived sense that the stars ahead of the astronaut will seem to slide to a point directly ahead of them while behind the astronaut, a ever increasing dark zone will continue to expand.  This dark zone contains the stars which have completely shifted out of the visually perceivable light band and no longer have any emission to detect at optical wavelengths read by the normal human eye.

Dr. Hasslein, if you travel at speeds approaching light, will you return having aged slower than any relatives or friends that you left behind?

Our extensive experiments involving sub-atomic particles artificially accelerated to near relativistic velocities, as well as extremely precise clocks mounted in our fastest test jets all seem to confirm that an astronaut and a clock moving at very high speeds will see time pass more slowly than a astronaut and a clock which is completely at rest.  But for the kinds of speeds we can generate in our own atmosphere, even using our fastest jets, the amount of time that can be measured is only very minute fractions of a second.  When we apply these same testing criteria to various sub-atomic particles, we can accelerate them to 99.9999 percent of the speed of light (POTSOL).  As these particles approach the speed of light (ATSOL), we witness very real changes in their relation with time ( as we understand it) as the individual lifetimes of these particles become many times longer than what they should be if they were not traveling so fast. The effect seems to be real enough, given our criteria for testing.  My hypothesis on time thrust will bear this out during flight, I'm sure.

Dr. Hasslein, you have shown that we can get very, very close to the speed of light, but why can't we travel faster than light?

Quite frankly, we simply do not know.  Our understanding, and I admit it is a rather limited understanding, even at this advanced stage, of the universe is that nature simply exacts too severe a penalty on any process that tries to break the light speed barrier.  Research so far points that this just seems to be the way that our particular universe is put together, it is a law that appears unbreakable at the current point in time and research.  Further research, better understanding, and more knowledge may show that we are wrong, and that there is a way to travel faster than light.    However, currently, the answer to the question is that we cannot travel faster than light because of the way that the universe operates.  The one inherent law of physics that prevents us from traveling faster than light appears to be rather absolute. We, as scientists and explorers, might not like this law, but like many other laws we seem obligated to live by, this is one we have never seen violated and one we will just have to live with.  For now.

Dr. Hasslein, we used to think that the speed of sound was an impassable barrier but we broke that twenty years ago.  Isn't the speed of light the same kind of barrier?   Won't we break it as well if we just keep applying enough intelligence of design and power application to the procedure?

Sadly, this is a romantic notion, but it has no scientific basis.  It is foundless for the mere fact that the constant that we use, the speed of light, as we understand the operations of the universe, permeates every scientific experiment that physicists and scientists have conducted for the last 120 years.  In all of that time, using constantly evolving scientific instruments, methodology, and deeper understanding, not one single crack in this barrier has ever been measured to even suggest that matter or energy, in any form, regardless of power applied or the intelligence of design for the medium through which it is transported,  can ever travel even so much as 1 micron per second faster than the speed of light.  If there is a way to do it, neither nature and God are telling us by showing a single phenomenon where it naturally happens or allowing us to create such an instance artificially using what we can here on Earth.  Again, I fear, that the speed of light is not only an absolute, it is an absolute barrier.

Dr. Hasslein, if there is so very little friction in outer space, then why can't we just use a powerful enough rocket to attain the speed of light?

The absolute barrier that we call the speed of light is a limitation which is firmly built into the space-time continuum itself.  The barrier that is the speed of light  is an integral  property of the gravitational field and the constant workings of the universe. Nature, and all forms of matter and energy present therein, seem to be locked in to this velocity limit, forced to obey without question, and there is nothing that we can do to the matter and energy within our space-time that can force it to or allow it to exceed this very finite limit. We can no more exceed the speed of light using simple brute force than we can alter any of the other myriad constants that we know exist in Nature.

Dr. Hasslein, According to the theories of relativity as we know them, how much younger would astronauts in earth-orbit be if they stayed there for six months before returning to Earth?

An interesting question.  Lets presume that the astronauts travel at a speed of 20,000 miles per hour. This is 9 kilometers/sec or 0.00003 of the speed of light. This high velocity produces a very special relativistic time dilation factor of 1+.5*(.00003)^2 = 1.00000000045, which can be measured in a minute amount.  If you multiply this result by the 6 month trip, then we arrive at the conclusion that the astronauts would be about .007 seconds younger than if they had stayed on the Earth.    That is, the astronauts in their spacecraft would have aged 0.007 seconds LESS than the people on Earth.  There is a very slight gravitational time dilation effect ( 1 - 2GM/rc^2 )^1/2 because their trip was at a lower gravitational field than on the surface, but this is not very large compared to the special relativistic factor which itself provides much more astounding results and effects.

Dr. Hasslein, how would a spacecraft traveling at near the speed of light appear to us here on Earth?

A spacecraft traveling away from us at very high relativistic velocities would have its entire spectrum red-red-shifted.  The variable differences of the time it takes for visible light to travel across the various refracting surfaces of the spacecraft would cause the spacecraft to be seen as a rotated or otherwise deformed object.  The image would not be easily recognizable for what it was, to the untrained eye.

Dr. Hasslein, does time stop when you travel at the speed of light?

This is a question more in line with theory and hypothesis than actual fact, since no matter can ever travel at exactly the speed of light.  We understand from experiments that the various half-lives of unstable particles, particles such as muons, are prolonged in regard to our reference of time frame.  These half-lives are prolonged by an amount predicted from their speeds by special relativity.  Using these examples and by means of  scientific extrapolation, we fully expect that for particles or matter moving at nearly the speed of light, their frames of temporal reference are greatly increased.  In essence, this means that to a particle accelerated almost to the speed of light, that a single second of the particle's life, according to its frame of temporal reference, might be days or weeks or even longer in our outside frame of temporal reference.  So, as your question asks, does time 'stop' at relativistic speeds?  Our answer is that time simply slows.  Time flows slower the closer you get to the speed of light.  The higher percentage you travel at relativistic velocities, the greater the time dilation will be.  We suspect that a spacecraft moving at very high percentages of the speed of light (POSOL) could travel days of interstellar distance, where to us, here on Earth, the spacecraft would travel for three days and cover an incredible amount of interstellar distance.  To the crew aboard that spacecraft, those three days could be seen and experienced under their frame of temporal reference to be merely minutes.  We cannot fully answer your question, because we do not fully know the answer.  However, our tests and experiments show that as you approach the speed of light, time slows down.  The faster you go, the slower time moves forward, but only for the spacecraft and the crew who are traveling at such high speeds.

Dr. Hasslein, do you anticipate that can we exceed the speed of light by somehow manipulating space-time?

I would like to say that currently, in nothing other than science fiction is there a way to exceed the speed of light or to transmit matter or information in that manner .  Using poetic terms like 'space-time' and 'worm holes' does not provide any proof that such concepts actually exist in our universe.   As scientists, we simply must require hard evidence and concrete proof that nature or the workings of the universe itself permits such phenomena to exist naturally.  At this time, evidence that any of these phenomena exist naturally is completely lacking, and for the ability of such a phenomena to be created artificially, we would have to have some basis, firmly established in the laws of the universe, upon which to build our creation.    Physicists have been, for many decades, accelerating electrons to within a millimeter/sec of the speed of light and recording the results.  Not one instance has been documented where any departure from what is strictly permitted by our understanding of  relativity.  I'm afraid to tell you that there is no 'gap' or 'quirk' that has ever been accidentally or experimentally discovered that shows light-weight electrons can surmount the speed of light, and if we can't get electrons to go faster than light, it is a sure bet that we can't get a spacecraft to do so either.

Dr. Hasslein, if an object approached the speed of light, would it be transformed into light?

No. This is amateur physics reasoning that I often hear, but it holds no water simply because "light", as we know and understand it,  has what we call a 'zero rest mass'.   No material body, not even an electron, can approach such an amazing condition naturally or artificially.  We have learned, as we accelerate particles to very high percentages of the speed of light (POTSOL) that the non-zero rest mass of the particles being accelerated would always prevent us from actually attaining a true light-speed velocity.  We can get very, very close, but we can never actually accelerate a particle or matter to the speed of light due to the difference in the mass.    "Light", as you well know, consists of oscillating electric and magnetic fields which are located at right angles to each other and at the same time, at right angles to their direction of travel. No material particle, as we understand physics, can be made or forced to do this, using natural or artificial means.

Dr. Hasslein, does gravity travel faster than the speed of light?

Gravity does not appear to travel faster than light, as a force and a constant, gravity appears to travel exactly at the speed of light.  Einstein postulated a relativistic equation for gravity that was based on general relativity demands that the force of gravity travels at the speed of light, otherwise the predictions we achieve for the phenomena of light bending and the precession of the perihelion of the planet Mercury would be very different than what we have experimentally determined to be true.  As you know, we can send spacecraft on very long journeys through the solar system, and soon even beyond the solar system to other stars.  As these spacecraft accelerate away, often at high percentages of the speed of light, the distance between the Earth and these spacecraft will become very great indeed.  So great will the distances be that the time it takes for light traveling between Earth and the spacecraft will be measured in hours, days, weeks, or even months.  If gravity traveled at any other speed than the speed of light, then the precise navigational trajectories that are often calculated for spacecraft would always come out incorrect.  That is for the simple fact that these trajectories always include gravitational influences that constantly change from moment to moment as the spacecraft, the sun and the planets change their own positions with respect to each other.  If gravity traveled either slower than or faster than the speed of light, then we would never be able to correctly calculate all the inherently different time delays of these gravitational influences in order to correctly plot and navigate the flight of the spacecraft.

Dr. Hasslein, what exactly is it that physically prevents us from achieving faster than light speeds?

At this time, we really do not understand why it is that nature or God has decided that the constant of C = 186,287.9 miles/sec is to be the absolute fastest speed allowed in our particular four dimensional reference of space and time.  Countless experiments have shown that if you take an electron and boost its speed, increasing its velocity in ever rising amounts, that the electron behaves as though it is physically gaining mass.  The faster the electron is accelerated, the more massive it becomes.    In this limitation, as matter approaches a velocity of the speed of light, the amount of energy required to boost that matter one inch/sec faster outstrips first the energy available in your local power utility, than your nation, then your planet, and so on until the power demands approach requiring infinite power to move infinite mass.    Exactly why this happens can only be accurately explained by the special relativity equations and using a zillion decimal places.  Still, exactly why this effect should be so, no one has a thorough understanding at this time.

Dr. Hasslein, what happens to the fabric of space-time when an object moves through it travelling at velocities that are near the speed of light?

I must argue a point of reference here.  For all of our better understanding, "space-time" is not a fabric as you would rationalize "fabric".  Space and time, as well as many, many other things by which our universe apparently operates, are not tangible 'things' in the same way that soil and rock are.  It is, therefore, incorrect to think of these 'intangible' phenomena as having a physical 'medium' or representation at all.   No physicist or astronomer who is educated in these sciences even begins to consider that space-time is a truly physical tapestry through which we might be able to 'punch a hole', as it is commonly thought.   Giving tangible references to intangible is the way that our minds often prefer to conceptualize.  This concept of giving an intangible phenomena a tangible trait has been a problem of science, both the amateur and professional aspects, since the 19th century and maybe even farther.  It was during the 19th century that physicists once talked of an "ether" or a medium beyond the air we breathe through which me might simply sail to other worlds, using air ships and propellers. Today we know that these "ethers" that  behave like a physical medium are simply not founded.    They are romantic concepts, from a time when more scientists were romantics.    I hold the same to be true today.  The mind prefers to draw pretty pictures instead of the hard, cold logic often required, and these pretty pictures are sometimes misleading.

If space-time is not a fabric, a physical representation of the surface which covers all parts of our universe, then what is it?  Science really does not know what space-time is at this juncture in our knowledge.  The only clues we have are hinted at us by quantum mechanics and general relativity.  General relativity, presented by Einstein, says:

"Space-time does not claim existence in its own right, but only as a structural quality of the [gravitational] field".

Einstein even noted that "Space and time are modes in which we think, not conditions in which we exist". 

This view was also expressed early in 900 AD by Ikhwan al-Sufa, an Arab physicist who said that: "Space is a form abstracted from matter and exists only in (the) consciousness".

So, the question about what happens to space-time when a particle moves through it at near the speed of light is answered by saying that such a question is simply the wrong question to ask.

Dr. Hasslein, what visual distortions, if any, will occur to the astronauts as their speed approaches high percentages of the speed of light?

Astronauts in a spacecraft approaching high percentages of the speed of light will notice that the light from objects directly ahead of their speeding spacecraft will undergo a strong blue shift and that objects to the stern will undergo a strong red-shift.    As their speed increases and the POTSOL is added to, the red-blue shifting will become so extreme that all visible light from the stars that are in front of the spacecraft and the stars that are to the rear of the spacecraft will be phase shifted completely out of the known visible spectrum.  When these stars move out of our perceptible wavelength, the stars will simply appear to fade to black or vanish against the background.  There is another kind of relativistic effect, an interesting effect which causes an apparent displacement of the visible images.  This curious effect is called relativistic aberration, or the aberration of light.

The relevant formula is:

                            cos (Theta) +  (V/c)
Cos (Theta) =  ----------------------------
                          1 + (V/c) cos (Theta)

This equation assumes that the variable V is the velocity of the spacecraft.   The variable Theta is the angle between the star and the direction of travel when the spacecraft is at rest, and Theta is the same angle measured when the spacecraft is in motion.

Astronauts looking in the direction of travel will notice that the star images shift to smaller angles, Theta, in the direction of travel.  At 75 percent of the speed of light (.75C POTSOL), the stars that are 90 degrees from the direction of spacecraft travel will have now shifted to a position some 41 degrees from the direction of motion in the sky. At even higher POTSOL, all of the stars in the forward hemisphere will shift to positions within a degree or less of the direction of travel of the spacecraft.  At ultra-relativistic speeds, all the stars will merge together into one 'star-like' object located directly ahead of the spacecraft, according to the astronauts' point of view.  If we take into consideration the Doppler effect, then light will become increasingly blue-shifted and the star-like object directly ahead of the speeding spacecraft will appear blindingly white.  Because the nature of the dominant source of radiation in the universe is found in the cosmic background radiation that permeates space, it is this blue-shifted light that will dominate what the astronauts see over the actual light from individual stars with regard to their forward line of motion.

In the opposite hemisphere, to the rear or stern of the spacecraft, a large dark spot will appear exactly opposite of the direction that our astronauts are traveling.  This dark spot will expand in size to engulf the entire hemisphere.    The faster the astronauts travel, the larger the dark spot gets, and the faster it grows in size.

Dr. Hasslein, why does time change when you travel near the speed of light?

I don't think any scientist or physicist is really sure why Nature wants to do things this way.  However, scientific research shows, in experiment after experiment, that this curious effect is exactly what happens the faster one travels.  This most curious effect is linked directly with how we, as a species, measure time.    Astronauts traveling at a high POTSOL will notice absolutely nothing strange about how their ship chronometer or a watch that they are wearing is measuring the passage of time.    However, someone on the Earth, who is moving far slower than the astronaut aboard their hurtling spacecraft, will notice that time passes slower for them than it does for the astronaut who is speeding away.  Time passes normally for the observer on the Earth, but for the astronaut heading away from the observer, the faster that the astronaut travels in relation to POTSOL, the slower time passes for the astronaut with relation to the Observer on Earth.  This process seems to be counter-intuitive to a line of reasoning, but a 'common sense' explanation for this curious effect will continue to elude us until we have more experience with flight time at high POTSOL.

Dr. Hasslein, can gravity affect the speed of light?

Gravity and light are two different forces of Nature, so the answer is that gravity cannot really affect the speed of light, nor can light affect the force of gravity.   Gravity may become so strong that it can bend light or shape light, but it is impossible for gravity to either accelerate or decelerate the speed of light.    Light simply cannot go slower than itself, nor can light go faster than itself.   Gravity is a changing constant, variable depending on acceleration and mass.   Light is a absolute constant, a true absolute that exists in our universe as we know it.  The force of gravity can change from location to location, but light will always travel at the same speed regardless of where in the universe it is.   As such, gravity and light are mutually exclusive with being able to affect each other, as we understand it, with certain exceptions. 

Perhaps our research into the bending of light under high gravity fields will yield interesting, or even startling data, but I must tell you that these experiments show that under the conditions where light might be bent or 'curved', that no human could survive, thus its application to manned spaceflight seems a dead end.

Dr. Hasslein, could you give us an example of the kind of time dilation that will occur as the astronauts head away from us at speeds approaching the speed of light?

As the various ANSA spacecraft leave our solar system for their own individual missions and destinations, I should mention here that the passage of time at speeds approaching the speed of light (ATSOL) where light travels at 186,000 miles per second.   As the crew of a spacecraft approaches the speed of light, time dilates or compresses in relation to the perspective of those aboard the accelerating spacecraft.   One example of this time dilation, the one you are most familiar with, uses identical twins.  At the age of 20 years old, one brother is a successful businessman, the other brother a successful astronaut.   As the astronaut leaves the Earth on a mission to a star 30 light years away and accelerates away at a velocity that is 0.999 the speed of light, he starts to undergo time dilation with respect to his perception of time aboard his spacecraft.

The mission at the destination star lasts for 6 full months of non-dilated time which the astronaut spends 'at rest', or at velocities far below the speed of light.   At the end of six months, the astronaut turns his spacecraft around, and again travels back to Earth at a velocity of 0.999 the speed of light.  When the astronaut arrives back on Earth, the astronaut has aged a mere 2.6 years or 2 years, 7 months, and 8 days, give or take some.  This means that when he arrives back on Earth, his actual age will be 22 years, 7 months and some days.  His brother, who remained behind, is now 80 years old, if he is still alive at all.  To the astronaut, he has experienced what we call 'subjective' time, or time that has moved very slowly.   To the brother that the astronaut left behind, time passed in what we call an 'objective' phase, which is what we normally measure time by.  The trip that took the astronaut only 2.6 years, the time it took him to travel to the star was measured by those on Earth in objective time which was 30 years.  The six months of objective time, which both the astronaut and the Earth bound brother experienced, spent at the other star are trivial, compared to the sixty-year round trip travel time for the astronaut.

Thus, there are two types of time measure used when people move at great percentages of the speed of light; "objective time" and "subjective time".  Objective time is the amount of time that passes 'normally' outside of the spaceship, to people who are not traveling at high velocities.  Objective time is 'normal' time that you and I measure by simply looking at our wrist watches or the clock on the wall.  It is time that passes for those who are not aboard the spaceship hurtling at great velocity away from the Earth.   Subjective time is time that is observed by those who are aboard a spacecraft that is hurtling away at high velocity.   The faster the speed of the vessel approaches that of the speed of light, the less subjective time is observed with regards to objective time.  Time passes much more slower for those travelling at higher velocities.  The following table is provided as a rough outline for our theory of time curvature as one approaches the speed of light.   As you can see, the closer you approach to the actual speed of light, the slower time moves for the traveler, and the faster time appears to move outside of the vessel, with respect to the traveler.