Among the astronomers who have expressed grave reservations regarding the customary interpretation of all cosmic red shifts as mere Doppler effects is Halton Arp. Śrī Arp formerly served on the staff of the Hale Observatory at Mount Palomar and is presently engaged in research at the Max Planck Institute near Munich, in what was then West Germany. While at Palomar, Arp carefully observed numerous instances of what are termed discordant red shifts—cases that do not conform to Hubble’s celebrated law. From his meticulous analysis, he has been led to conclude that red shifts, in general, may arise from causes other than relative motion alone.
At this juncture, a thoughtful person must inquire: why do scientists so firmly insist that red shifts are produced exclusively by the Doppler effect? It is indeed acknowledged that a Doppler effect can generate a red shift. But by what conclusive reasoning is it established that every red shift must arise from this single cause? According to prevailing physical theory, the only phenomenon aside from Doppler motion known to produce a significant red shift is a powerful gravitational field. When light ascends against gravity, it loses energy and thus becomes red-shifted. Yet astronomers dismiss this explanation for stars and galaxies, reasoning that gravitational fields of unimaginable strength would be required to account for the observed magnitudes.
Arp, however, contends that he has identified objects possessing high red shifts situated in close proximity to objects with low red shifts. According to the standard theory of an expanding universe, a body with a small red shift should be relatively near, whereas one with a large red shift should lie at a great distance. Consequently, objects that are genuinely close to one another ought to exhibit similar red shifts.
Contrary to this expectation, Arp presents the example of the spiral galaxy NGC 7603, which appears connected to a companion galaxy by a luminous bridge. Yet the companion exhibits a red shift some 8,000 kilometers per second greater than that of the spiral galaxy. Judging solely by this disparity, the companion should lie approximately 478 million light-years farther away. Nevertheless, the two galaxies appear sufficiently near to one another to be physically connected. By way of comparison, our own Milky Way galaxy is said to be only about two million light-years distant from its nearest neighbor, the Andromeda galaxy.
Predictably, defenders of the standard cosmological view strongly contest Arp’s conclusions. John N. Bahcall of Princeton’s Institute for Advanced Study asserts that there is no necessity to suppose that the two galaxies are truly connected. According to his view, they are widely separated in space and merely appear close together from our particular line of sight. The luminous bridge may indeed exist, but the more distant galaxy simply happens to be aligned behind it.
To support his objection, Bahcall offers a striking illustration: a photograph of a star within our own Milky Way that seems to be connected by a luminous bridge to a distant galaxy. Are they actually related? Bahcall explains that such a connection is impossible, for the star is a bright foreground object within our galaxy, whereas the distant galaxy lies some forty-four million light-years away.
Arp replies that this example is frivolous and misleading. The galaxy displayed by Bahcall is entirely ordinary, and the so-called bridge connecting it to the star is nothing more than one of its normal spiral arms. In contrast, Arp notes that the bridge in his own example is an unusual structure, not commonly observed in such galaxies. The probability that two galaxies of this particular type would coincidentally appear in such a configuration is, he argues, exceedingly small—far smaller than the chance alignment of a foreground star with a typical background galaxy.
Arp has documented many additional cases that appear to violate the conventional understanding of red shifts. Among the most controversial is his observation of a quasar, Markarian 205, situated near the spiral galaxy NGC 4319 and apparently connected to it by a luminous bridge. The galaxy exhibits a red shift of 1,800 kilometers per second, corresponding to a distance of approximately 107 million light-years. The quasar, however, has a red shift of 21,000 kilometers per second, which by standard reckoning would place it at a distance of about 1.24 billion light-years. Arp nevertheless maintains that the two objects are genuinely connected, thereby indicating that the customary interpretation of red shift is erroneous in this instance. It may be noted, in passing, that the practice of expressing red shifts in terms of kilometers per second itself betrays a firm commitment to the Doppler interpretation.
Critics obtained their own photographs of NGC 4319 and reported that they could detect no such connecting bridge. Some went so far as to claim that the bridge seen by Arp was merely a spurious photographic artifact. Yet more recently, Jack M. Sulentic of the University of Alabama conducted extensive photometric studies of the pair and concluded that the connecting bridge is, in fact, real.
Another example cited by Arp is found in the peculiar chain of galaxies known as Vorontsov-Velyaminov 172, named after its Russian discoverers. In this chain, the smaller and more compact member exhibits a red shift twice as great as that of its companions.
Beyond such paired galaxies, Arp draws attention to an even more astonishing phenomenon: it appears that galaxies and quasars may eject other quasars and even other galaxies. For instance, the exploding galaxy NGC 520 possesses a relatively small red shift. Along a straight line extending southwest from this galaxy are four faint quasars. Arp observes that these quasars are the only ones found in that region and asks whether it is reasonable to regard their near-perfect alignment as a mere accident. He considers such a coincidence extremely unlikely and therefore suggests that the quasars were ejected from the galaxy itself.
Notably, these quasars possess red shifts far greater than that of the galaxy from which they seem to originate. According to standard theory, this would imply that they are vastly more distant. Arp, however, interprets this and similar cases by proposing that newly ejected quasars are born with intrinsically high red shifts, which gradually diminish with time.
Some scientists doubt whether galaxies could possibly eject massive objects such as other galaxies or quasars. In reply, Arp points to a remarkable photograph of the giant galaxy M87, which is observed ejecting a jet of material. When one examines the surrounding elliptical galaxies in that region—M87 itself being elliptical—one finds that they lie along a line aligned with the direction of the jet. This, Arp suggests, indicates that these galaxies were expelled by M87.
This proposal naturally raises a profound question: how can a galaxy, understood as an “island universe” composed of countless stars, gas, and dust, emit another galaxy of similar composition? Some have suggested that radio astronomy may provide a clue. It is now generally accepted that vast regions of radio emission can be ejected from galaxies, often appearing in pairs on opposite sides. To account for this, astronomers have postulated enormous rotating black holes at galactic centers, which consume nearby matter and expel material along their axis of rotation. Yet if Arp’s conclusions are correct, one must explain not merely the expulsion of tenuous emitting gas, but the ejection of entire galaxies or their precursors.
With respect to the red shifts of such ejected objects, Arp observes a consistent pattern: although these bodies lie in close proximity to their parent galaxies, they display far higher red shifts. Arp insists that this can only indicate that their red shifts are not caused by velocity—that is, they do not measure recession speed. Rather, the red shift must be related to the intrinsic physical condition of the object itself.
At present, however, the established laws of physics offer no explanation of what such a condition might be. Since a galaxy is understood to be an aggregate of stars, gas, and dust, it is difficult to conceive of any inherent property that would produce a red shift independent of motion or gravitation. Such a phenomenon cannot be accounted for by known physical principles.
This circumstance appears to demand the formulation of new physics. Yet such a step opens a veritable Pandora’s box, for modern cosmology is firmly committed to the premise that the universe can be fully explained by existing physical laws. Should those laws require fundamental revision, all cosmological models founded upon them would likewise be called into question.
Arp’s findings are therefore highly controversial, and many astronomers remain unconvinced that the associations he describes between galaxies and quasars are real. Nevertheless, his work represents a significant and sobering line of evidence suggesting that the standard interpretation of galactic red shifts may not be as final or complete as is commonly assumed.
Deepen your Bhakti-yoga practice, harmonize relationships, and receive guided coaching — all at Vedavarsity.com
