*recently we received an email from a friend asking for clarification regarding some points. In response, Barry wrote the following, which is a good layman's summary of the material being questioned:*

**Your first query** suggests that there has been no reason found for the slowing speed of light. In fact, that situation had changed many years ago. The basic reason why also explained the changes in a number of other atomic constants. Let me, then, start at the beginning. We are told 12 times in scripture that the Lord created the heavens and stretched them out. Science, generally, agrees that there was indeed an initial fast expansion of space. Given this background, you might like to read what we have on our website here. You might also like to consider the following items.

Consider: when you stretch a rubber band, or inflate a balloon, you put energy into its fabric. When space was expanded, energy was also put into its fabric. To simplify the explanation, let me say that this energy ultimately appears as the Zero Point Energy (ZPE) of the vacuum. This energy is present when a vacuum is cooled to zero degrees Kelvin and for that reason is called the Zero Point Energy. The ZPE, even in a small volume, is incredibly large and is in the form of electromagnetic waves of all wavelengths. Science has shown that the ZPE has many more small wavelength waves than large. Therefore, as the universe expanded, more and more energy was put into the fabric of space, so the ZPE continued to build up.

Consider the waves you see on the ocean. When they intersect, they form white-caps which disappear a short while after. In a similar way, where the intense number of randomly intersecting waves of the ZPE meet, there is a concentration of energy. On the basis of Einstein’s famous equation, energy and matter are interconvertible. So, for a brief moment, where the energy concentration occurs, virtual particle pairs form. These pairs are positively and negatively charged and exist briefly, then slam back together again and go back to energy. It can be calculated that at any instant there are at least 10^63 virtual particle pairs in any cubic yard of the vacuum at this point in time. Since the ZPE waves are moving, the virtual particle pairs with their positive and negative charges are also moving. A moving charge is an electric current and all electric currents have circling magnetic fields. Therefore, these virtual particle pairs give rise to the electric and magnetic properties of the vacuum.

Two things now become apparent. As the ZPE strength built up, so, too, did the number of virtual particle pairs. Thus, over time, as the universe expanded, and the ZPE strength increased, the numbers of virtual particle pairs in a given volume also increased. This means that the electric and magnetic properties of space changed with time. The outcome is that all electro-magnetic phenomena are going to be affected in a predictable way. Since atomic clocks and their interactions are basically electro-magnetic in character, then their rate of ticking will slow down as space became “thicker” with virtual particle pairs. In a similar way, lightspeed will slow down. As a photon of light proceeds through the vacuum, it hits a virtual particle, gets absorbed, the pair annihilate and the photon goes on its way…only to interact with another virtual particle pair. Thus, the path of the photon is like a runner going over hurdles; the more hurdles there are in the designated distance, the slower the elapsed time will be. The math using the electric permittivity and magnetic permeability of free space is quite straightforward as both depend on the ZPE strength and the virtual particles. That is as basic as I can get for you showing why the speed of light and the rate of ticking of atomic clocks has changed. Further details can be found on our website here.

**Your second main point** is that it is awkward for the speed of light to have slowed down to such a small rate of change just at this point in time. You similarly suggest that there is no reason for that apart from the fact that atomic clocks have been measuring the flight time of light photons over a set course. While that is certainly true, there have been some important developments here as well which come from other data. You might like to consider the following items. Please bear with me as we have an unusual starting point.

It is standard science to say that universal expansion is ongoing. However, this is not the picture that emerges from data like the distribution of hydrogen clouds in space. At any given moment, the distribution of such clouds will be very approximately consistent throughout the volume of the universe. In the early days of the universe, when the cosmos was smaller, because expansion had not been going on for long, the clouds were much closer together. This is indeed observed at the most distant parts of the universe. As expansion continued, the hydrogen clouds got further and further apart. We see this process occurring as we come forward in time from the original highest redshifts (about z = 10 or more) down to a redshift of about z = 2.6. Then, as we come closer to the present epoch, the expansion process then slows to a stop at a redshift of z = 1.6. Then from a time corresponding to a redshift of 1.6 down to the present, the hydrogen clouds have remained at a fixed distance apart. In other words, the universe did expand initially, slowed down and was then relatively static from that point on. From the point that the cosmos became relatively static, no more energy was being put into the fabric of space. Following this event, the conversion of expansion energy into the ZPE continued by the same process operating as before, since the conversion was not an instantaneous action. Once that well-defined process was complete, the ZPE reached its maximum value.

Importantly, Narlikar and Arp in 1991 showed that any such static cosmos with matter in it would be stable against collapse provided that it oscillated slightly in several modes simultaneously. This meant that, once the ZPE had finally built to its maximum, its strength will, nonetheless, oscillate somewhat. Because of this universal oscillation, when the cosmos is at its minimum size, all the ZPE waves will be forced to occupy a smaller volume. As a result, the ZPE strength will be greater and the number of virtual particle pairs per unit volume will be at a maximum. When the universe is at its maximum extent, the same number of ZPE waves will be in a larger volume. Thus, the ZPE strength will be less as will the number of virtual particles per unit volume. Since this oscillation affects the ZPE strength, it will also affect the rate of ticking of atomic clocks and the speed of light. This oscillation can be traced in atomic clock data back to about 2000 BC. In addition, this oscillation has been picked up in measurements of other electromagnetic quantities, separate from lightspeed, in the period from 1940 to 1990. These curves support the contention that we are currently near a temporary minimum caused by the effects of the oscillation modes of the cosmos on the Zero Point Energy. These data also verify the theoretical approach of Narlikar and Arp. Some additional information and graphs can be found on our website here.

**The final point that you make** concerns an experiment that you suggest should take place to settle the issue about whether or not lightspeed is still dropping. The oscillation data actually suggest that lightspeed might even be increasing slightly at the moment as we picked up a change in the trend direction around 1970 as shown on the graphs here and figures 4 and 5 here.

You suggest that some of the moons of the outer planets may be employed, just like Jupiter’s moon Io was initially, to measure the speed of light, and results compared. There is a problem with that! Space-probe data have found that these moons are deep inside the magnetic fields of these giant planets. The data show that electric and magnetic interactions are occurring between the moons and their parent planet which results in the degrading the orbits of these moons, sometimes erratically. Therefore, since timing of the orbital characteristics is the key to lightspeed measurements, nothing definite can be found from that source of data because of the degrading orbits. But it was a good suggestion.

On the other hand, direct atomic clock measurements of planetary orbital characteristics have been made. The graphs of this have shown a slow-down in atomic time (just as it has for light) with a slight upturn around 1970 – similar to the results from other atomic constants. This then suggests that lightspeed reached a minimum around 1970 and increased marginally after that as I mentioned above. Many quantities are now being linked by convention to an absolutely fixed speed of light. Therefore, any quantity suspected of showing a lightspeed-linked variation will need to be carefully chosen. However, there is one way of measuring the speed of light which is not affected by these conventions. It is the aberration method of measurement of lightspeed. This method measures angles, not times or distances. Therefore, it should theoretically be possible to keep a cross-check on lightspeed behavior independently by this method.

**You then suggest** that I should undertake some such series of experiments. Thank you for the vote of confidence! In actual fact, I am now 75 years old and my health is too precarious to allow any such undertaking. This is particularly the case since a comparison of data values would have to occur over at least a decade. As a consequence, that process will have to be left to someone else.

I hope all this clarifies the current state of the research.