It is one of the curious ironies of scientific progress that quite often when scientists feel that a certain theory or concept seems to adequately explain all observed phenomena related to any particular field, they suddenly come across a development that shakes their confidence almost compelling them to revise their opinion. The discovery of the existence of what is now being described as a “hole” in space by astronomers visiting an observatory in Arizona in the United States is a case in point. It is felt in some circles that this newly discovered hole i.e. a large region with no galaxies may pose a riddle to the supporters of the “Big Bang” Theory which is now the best explanation for the creation of the Universe.
There has been a lot of controversy in respect of the existence of such a vast hole in the depths of space. This hole, however, has nothing to do with a black hole most astronomers are familiar with. When astronomers speak of a Black hole they are referring to the black region around an old collapsed very massive star, which is pulling so strongly that not even light can escape from it. Very complex physical laws and mathematical equations are required to understand that phenomenon (Stephen Hawking of Cambridge University, England, and Roger Penrose of Oxford carried out extensive researches on Black holes.) But the “hole” in space that we have referred to above is an entirely different phenomenon.
The astronomers (visiting the observatory in Arizona) who discovered this Hole were studying the distances of galaxies. The distances of remote galaxies are measured by the “red shifts” in their spectra. A red shift- a displacement of the spectral line towards the red or long wave end of the spectral band—indicates a velocity of recession. The universe is believed to be expanding and the farther away a galaxy is, the faster it races into space.
This is the view of Edwin Hubble who studied these phenomena in depth. The factor relating the speed of a galaxy to its distance is known as Hubble’s Constant which can be used to arrive at that time in the past when all the galaxies were packed together. Therefore, the velocity of recession is a fairly reliable way to measure the distance between a galaxy and ourselves.
The Astronomers at Arizona were measuring the red shifts of galaxies in six selected regions, three in the northern hemisphere of the sky and three in the southern hemisphere. It was the northern region, in the general direction of constellation Bootes (the herdsman) that caused all the flurry of excitement. Galaxies were clumped about 300 million light years away from Earth which is a fairly modest distance by cosmic standards (a light year is the distance travelled by light for a whole year at the velocity of 186000 miles per second). There were also galaxies clumped at about 600 million light years away. But, strangely in between, there were absolutely no galaxies at all. The astronomers were first unwilling to believe this as they found it to be rather peculiar. They checked, and rechecked several times. But the results were the same. Moreover, other observations suggested that the void or the hole had to be at least as wide as it was deep and approximately 300 million light years in diameter.
How could one find the answer? One possible explanation is that some material is obscuring the galaxies in this area. But this could not be because we would not see galaxies on the far side of the empty region. Another possible explanation is that galaxies in the “hole” are so “faint” that we cannot detect them. This also seems not the correct answer since there are no spectral regions in which galaxies are particularly bright or dim.
A completely different suggestion was put forth by England’s famous, though controversial Astronomer, Sir Fred Hoyle who has been interested in studying interstellar and also intergalactic materials spread through space.
Hoyle suggested that the galaxies inside the hole are perhaps shrouded in cocoons which effectively shut in their light. This seems to be the most plausible suggestion yet. There are galaxies that contain a great deal of matter and there seems to be no valid reason why some galaxy should not be completely hidden. But the explanation is not entirely satisfactory. Why should there be so many “cocooned” galaxies in a particular state of evolution in one particular region. It could be that we are dealing with a cluster of galaxies in a particular state of evolution but nothing of the sort has been suspected elsewhere.
The absence of physical galaxies, however, does not necessarily mean that the area is entirely empty. There could be a vast amount of thinly spread material that we can’t see. Infrared studies of the hole may yield some result especially if the cocoon theory is right. But this hasn’t been attempted yet.
Anyway the general consensus of opinion among eminent astronomers is that the hole is real. A vast region has really been discovered in space in which there are no galaxies. This could have a profound impact upon current cosmological thinking. At the moment, the Big Bang theory is popular. According to this theory which was spelt out in detail by Albert Einstein, the matter in the universe—enough to make a hundred thousand million galaxies—was all concentrated in one small mass of incredible density about 15 billion years ago. This “primeval atom” or small mass exploded for some reason sending matter out in all directions and as the expansion slowed down a steady state resulted at which time galaxies formed. Something again upset the triggering and expansion of the universe which is still continuing. There are variations. There may have been no steady state as indicated above. But basically this “evolutionary theory” or ” Big Bang theory” takes it that the universe was created at one place at one point in time and has been expanding ever since. The existence of a very large area with no galaxies certainly poses interesting and different problems for Big Bang or Evolutionary theorists. It would however no doubt ironically provide fascination for Astronomers like Hoyle who are opposed to the Big Bang theory and believe in what is known as the “steady state theory” of creation. Hoyle and some others maintain that universe as a whole has always looked the same and always will. As the galaxies expand away from each other new material is formed in some way between the galaxies and makes up new galaxies to replace those that have receded. Thus the general distribution of the galaxies is the same. Though how matter would be formed in this way is hard to see, it is perhaps no harder than seeing why it should all form at one place at one time.
How do we decide which of the theories is closest to truth. Since the very distant galaxies are thousands of millions of light years away we are seeing them as they were thousands of millions of years ago. If the Evolutionary Theory is correct then the galaxies were closer together in the past than they are now and so distant galaxies ought to appear to be closer together than the nearer ones. According to the Steady State Theorists there should be no difference. Available evidence seems to suggest that there is a difference and that the galaxies were closer together than they are now and so the Evolutionary Theory is partially confirmed and the Steady State theory in its original form at least has to be rejected.
It is much too premature to say anything finally on the subject of the “hole” discovered by the Astronomers from the observatory at Arizona. Their observations no doubt seem reliable but they are preliminary findings. Some Astronomers are inclined to believe that it is not impossible that there has not been a serious mistake in the interpretation of the observations made from the observatory at Arizona. They also question the universal validity of the red shift distance relationship. But unless the Arizona findings are proved wrong, we would have to accept that there is a “vast hole” somewhere out there in space and that Hoyle’s “Cocoon Theory” appears to be the most convincing explanation of at least the “Vast Hole” phenomenon at least for now, notwithstanding the fact that his “steady state theory” of the creation of the universe, has been discarded.