Shlomo Ezagui

God’s Timelessness, Kefitzat Haderech, and the Physics of Light

Karsten Winegeart

God’s essential name, the tetragrammaton, loosely translated, is saying that God was, is, and will be all in one. The past, present, and future are all one in God. To God, the future is like the past, as is the present. God, of course, created time, but that is a lower and more peripherally measured expression of God.

It is impossible for us humans to truly appreciate a dimension beyond the parameters of time. Light, as the most transcendent and sublime of all creations, gives us a small appreciation of what beyond time might mean.

Time is not what you think it is.

If the speed of light is an absolute constant, then time, space, and matter are all relative, according to Einstein. The speed of light is not only absolute, but it also calibrates everything important in the universe, including time!

We usually consider time to be an absolute. We have the impression that time moves at the same rate for everyone because of our experience with the constant ticking of a clock, and that time is governed by some external universal clock that is the same for everyone. So, how can time be relative?

Let me demonstrate this concept with a simple thought experiment involving a laser beam reflected from a train mirror. A light beam travels from the laser to the mirror, is reflected, and then returns to the laser. The light beam moves straight up and down vertically to an observer sitting on the train. From the reference frame of a person standing on the ground watching the train go by, the light beam traces a zig-zag path reflected from the top mirror.

If the person on the train wants to measure the speed of light, they will measure the distance that the light travels along the vertical line between the laser and the top mirror and the distance that the light travels from the mirror back to the laser. The total distance will then be divided by the time it takes for the light beam to bounce back and forth. This is because speed is defined as the distance something travels in a given amount of time.

If the person on the ground attempts to measure the speed of light, they will measure the distance traveled by the light along the zig-zag path and divide it by the time it takes for the light beam to travel up and back down to the laser. Because the zig-zag pattern traces a longer distance than the vertical, the person on the ground calculates the speed of light to be greater than the speed measured by someone on the train.

A greater distance divided by the same amount of time will result in a greater speed since Speed=Distance/Time

We have a problem based on what we presented earlier! This contradicts the principle that the speed of light is constant for all observers. How can both observers measure the speed of light at different rates when the speed of light is absolute and independent of the observer’s reference frame?

When the person on the train and the person on the ground compare notes, they will notice that the person on the ground measured the speed of light at a higher rate!
Einstein realized that for both observers to measure the same speed of light, the time measurement must change proportionally to the length change. Because speed is defined as distance divided by time, a longer distance divided by a longer time produces the same result as a shorter distance divided by a shorter time.

If each observer measures a different time so that the ratio stays the same, then the speed of light remains the same. This is illustrated by the fact that 2 divided by 2 is the same as 5 divided by 5. Both ratios result in the number 1. Essentially, Distance/Time=Distance/Time

So, in order for the speed of light to remain constant for both observers, the time measured by the person on the train must be less than the time measured by the person on the ground. The light beam would have taken longer to travel from the laser and return to its starting point after reflecting off the mirror for the person on the ground.  How can two different observers measure different durations for the same event? This can only occur if each observer’s time flows at a different rate! The clock of the person on the train must move slower when compared to the clock of the person on the ground!

The zig-zag stretches out further as the train moves faster, and a stationary observer’s total distance traveled by the light beam on the ground increases. This means that the clock on the train moves even slower than a clock on the ground.

As the train approaches the speed of light, the clock slows down. Time would come to a complete halt on the train if it could reach the speed of light. If the train could travel at the speed of light, the passengers would be immortal. If the train were traveling at the speed of light, an infinite amount of time could elapse for someone standing on the ground while no time elapsed for the person on the train.

After further consideration, we can conclude that a person on a train traveling at the speed of light experiences timelessness! Essentially, all points are merged into a single point in time. The person on the train is not moving through time by a single millisecond, whereas the world outside the train is!

When Einstein’s theory was first published, no one believed it. After careful experimentation, the data conclusively demonstrated that Einstein’s theory was correct!

The clock slows down as someone moves faster. The person in motion is unaware of the slowing of time because the clock in their head is also slowing! Nothing has changed for the person riding the train. It appears to be business as usual. The moving person’s clock only appears to be moving slower when observed by someone not moving with the clock! That is, time is not an absolute quantity. Time is completely relative.

It is critical to note that this time difference is negligible at the speeds we normally travel in a car or a plane. As an example, the clock of someone moving at 60 miles per hour runs at 0.999999999999996 times the rate of a clock that is stationary in a person’s home. A clock in an airplane moving at 500 mph runs at 0.99999999999972 times the rate of the clock on the ground. These small-time differences are imperceptible in most situations.

However, these minute time differences are significant and required for GPS satellites. Because the clocks on GPS satellites run at a different rate than those here on Earth, the GPS in your phone is based on this math. Due to special relativity, this time difference is minimal because the GPS satellite’s clock slows down by 7 microseconds (7 millionths of a second) per day. This is due to the satellite’s orbital speed of 14,000 kilometers per hour. If this minor time difference is not considered, it will result in a significant miscalculation of distances on Earth.

(It should be noted that there is also a time difference on satellite clocks due to General Relativity, which Einstein developed after introducing Special Relativity. Einstein demonstrated in General Relativity that gravity affects the rates at which clocks move. More on this, God willing, in the future when I discuss the relationship of mass with gravity and time.)

These differences are more pronounced at speeds that are a significant fraction of the speed of light. A clock in a spaceship traveling at 50% the speed of light, for example, runs at 86.6% the rate of a clock on Earth (i.e., the clock runs 13.4% slower). This means that if this spaceship traveled at this speed for 86.6 years before returning to Earth, 100 years would have passed. This space traveler believes they have traveled 14 years into the future. The space traveler appears to be traveling into the future because they experienced 86 years according to their clock, while everyone else on Earth experienced 100 years. As another example, if this spaceship traveled at 99% the speed of light for the same 86.6 years, 613.89 years would have passed on the earth. This space traveler would feel like they traveled ~527 years into the future.

All this appears impossible, but time relativity based on the absolute speed of light has been proven to many decimal points in countless experiments.

If someone could travel at the speed of light, their clock would move infinitely slowly. In other words, their clock would be completely stopped while clocks on Earth continued to tick. This space traveler could travel indefinitely into the future and feel like no time had passed! If someone could travel at the speed of light, they could simultaneously experience all points in time!

We are familiar with many Bible stories, Talmud, and of our sages who experienced Kefitzas Haderech.

The common understanding of kefitzas haderech is that the person travels at dizzying speeds. According to this explanation, the word kefitzah means to jump: the person “jumps” and covers great distances in a very short amount of time.

Rashi, however, translates the word kefitzah in kefitzas haderech differently and quotes the verse “Lo sikpotz es yadcha – Do not CLOSE your fist to your poor brother [and refrain from giving him Charity].” The term kefitzah (Sikpotz) means to close the hand, causing it to take up less space than usual. Accordingly, kefitzas haderech means that the physical earth compresses and takes up less space.

As the person picks up speed, time and space dilate. According to Albert Einstein’s theory of special relativity, time and space undergo dilation as an object moves faster and approaches the speed of light. Both explanations of Kefitzas Haderech are correct and complement each other in describing the effects of relativity.

Back to God, may He be blessed.

Because light is essentially “timeless,” this exceptional and unusual property of light can help us somewhat relate to the timelessness of God. The peculiar properties of light correspond to the characteristics of an infinite God: Time does not confine or constrain God. God does not move in a straight line through time. God exists outside of time, and time, like space, matter, and energy, is a created thing. God, like light, experiences all points in time (past, present, and future) simultaneously. God sees the end from the start. God has His finger in the past, as in the future, as in the present.

Pray to God since nothing constrains His possibilities.

About the Author
Rabbi Shlomo Ezagui is an author and lecturer. "A Spiritual Soul Book" ( & "Maimonides Advice for the 21st Century" ( In 1987, Rabbi Ezagui opened the first Chabad Center in Palm Beach County, Florida, and the first Orthodox Synagogue on the island of Palm Beach, Florida.
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