University Lowbrow Astronomers

STICKING TO THE COSMIC SPEED LIMIT.

by Lorna Simmons
Printed in Reflections:  January, 2000.

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I have often wished that some hapless traffic enforcement officer would ticket me for driving over the speed limit, at which time I would inform him/her that I actually was traveling much faster than that -- much, much faster.  In fact, if the traffic cop really wanted to clock my velocity in the accelerating expansion of the cosmos, such recorded motion should be actually considered as ending with the speed of which my car is traveling (which, while non-zero, will forever be kept a secret).  As a reference point, or “rest frame,” the Cosmic Microwave Background Radiation (CMBR) herein will be considered to have a measurement of zero velocity against which all of the remaining cosmic motions are computed.  Naturally, from here on in, everything being discussed actually happened sometime in the distant past, the intervening time depending upon the cosmic distance.  None of the objects are actually in the positions where we now observe them.  Therefore, keep in mind the changing velocities and positions in the cosmos with respect to time.  Of course, there is no simple addition or subtraction involved, and the combination of velocities and/or accelerations (both positively and negatively) are much more complicated than what is being stated here.

Therefore, for the purpose of simplicity, we will combine my car’s mysterious velocity with the speed of the earth’s rotation on its axis (1,610 km/hr), add that to the speed with which the earth is revolving around the Sun (30 km/sec), join that to the speed with which the Solar System is cruising in its path around the Milky Way (220 km/sec) and include the speed at which the Milky Way (a.k.a. “The Galaxy”) and the Andromeda Galaxy (a.k.a. “M31”) are charging toward each other -- approximately 300km/sec.  The Milky Way itself is recorded as traveling at 360 (+/- 20) km/sec toward the constellations of Leo and Crater.  In addition, there is the random motion of the galaxies within our Local Group -- 300 to 1000 km/sec.  Then there is the speed with which our own Local Group of Galaxies is traveling toward the Virgo Cluster, approximately 65-70 kilometers per second per megaparsec (km/sec/Mpc), combined with the speeds at which all of these neighboring galactic clusters are hurtling in the direction of the Great Attractor (again, approximately 65-70 km/sec/Mpc).  After all of that, it is necessary to consider the relative speeds of distant galaxies with respect to the Milky Way, which speeds have been reported as being approximately 2,000 km/sec for each 31 Mpc.  Finally, to top things off in style, it is important to consider the speed of the expansion of space between the galactic clusters -- the extravagantly excessive speed of the accelerated expansion of the Universe itself due to Lambda, the hypothetical energy density of the vacuum.  Two large groups of cosmologists, The Supernova Cosmology Project and the High-z Supernova Search Team, presently are working on the calculation of the recently found cosmic acceleration, so stay tuned.  To paraphrase a once-popular song from a bygone era, a lot of this means running around in ellipses, getting nowhere, because many of these motions are directionally contrary to each other and will partially cancel each other out.  Somewhere in this hodgepodge computation of confusing and contradictory calculations must be my actual cosmic speed.

Officer, I am traveling extremely fast!

Naturally, I would have to take the consequences for offering this unsolicited information and perhaps spend at least the night in the lockup at the local jail, or even worse, lose my driver’s license.  Would my fine be significantly increased to reflect of all of this additional cosmic acceleration?

Then, again, none of these velocities are actually that swift when compared to the speed of light (the speed of the photons of the electromagnetic spectrum) at exactly 299,792,458 meters per second (m/sec) in the “perfect vacuum of space” (although there is actually no perfect vacuum of space at all, since space has been indirectly observed as being filled with the roiling virtual particles and their antiparticles which are instantaneously coming into and out of existence through annihilation).  Therefore, there is a real (not-manufactured-by-humans) speed limit, actually a “constant” which is the aforesaid 299,792,458 m/sec, exactly.  This includes everything in the electromagnetic spectrum (which encompasses all frequencies of “light” at the radio, infrared, visible, ultraviolet, x-ray and gamma ray wavelengths).  Nothing containing mass (which means almost nothing except for light and other massless particles) can equal light’s speed limit (299,792,458 m/sec).  Nothing.  Almost nothing.  Relativity takes care of that, because at the speed of light, massive objects would attain infinite mass, and it would take an infinite amount of force (including fuel) to move them faster.  Actually, the light-speed rule applies to “information” which cannot travel faster than the speed of light -- never, ever, well, almost never, ever.  An imaginary crack must be left open for possible future discoveries concerning the speed of light.  Of course, in science fiction, things like superluminal speeds (faster-than-light warp speeds) are introduced repeatedly so that the characters in these dramas can get from here to there before the end of the next Millennium (at least before the end of that particular nightly segment of the hypothetical science fiction drama in question).

There actually are particles which can be measured as traveling at superluminal speeds, however trivially.  In quantum tunneling, particles have been measured as passing through a laboratory barrier and appearing instantaneously on the other side of that barrier.  Sometimes light might be measured as being superluminal while it is actually measured as traveling on an angle.  This makes it appear to be traveling faster than the light speed limit, until this angle is taken into account and the measured speed comes back down to, or below, the speed-of-light speed limit (299,792,458 m/sec).  Trivially, shadows can be thought to travel faster than light speed, but shadows (the absence of light) are not composed of matter particles, do not contain mass, and, for that reason, cannot be thought of as information carriers.  Then again, who knows what science will bring in the next Millennium (if ever people can agree upon the timing of the advent of the next Millennium)?

Gravitons (gravitational force particles), having no mass, travel at the speed of light.  In fact, as stated previously, all particles with zero mass travel at the speed of light.  Neutrinos and antineutrinos are said to travel at light speed.  Scientists have measured a very slight difference in mass between at least two of the six kinds (a.k.a. “flavors”) of neutrino (electron neutrino, muon neutrino, tau neutrino and their anti-neutrinos), because at least two kinds of neutrinos have been detected as “oscillating” (the act of changing from one kind of neutrino to another), thereby possessing mass.  However, it has not yet been determined just which particular neutrino kinds are doing the oscillating and, therefore, have mass.  The difference in kinetic energies recorded between neutrino kinds shows a difference in their mass squared which demonstrates that at least one, if not all, of the neutrinos studied probably has an extremely tiny mass (expected to be between 2 electron volts (2eV) and 30 electron volts (30eV).  Particles of the weak force, W+, W-, and Z0 (W plus, W minus, and Z naught), each of which has zero mass, also travel at light speed.  The door is left wide open (a large crack) for future particles which, as yet, are only figments of some theoretical physicists’ fertile imaginations.

Actually, light sometimes travels more slowly than other particles.  For instance, it slows down in water and in glass.  Therefore, sometimes things can travel faster than light, but only if light is traveling more slowly than “light speed.”  Details, details.  Confusing?  Recently, light was extremely slowed down in the laboratory to approximately 61.2 kilometers per hour (which, eventually, ought to end up earning at least one Nobel Prize for the scientists involved).  So, the speed of light is not always “the speed of light.”  It is just a speed limit at its upper end -- at least until physicists come along with new evidence.  That, naturally, is a gigantic “if”!

Confusing?  Whatever.

So, next time you receive a speeding ticket, resist all silly impulses which will get you into trouble (like attempting to educate the local constable).  Take the ticket.  Keep your mouth shut about your own projected cosmic velocity and/or cosmic acceleration in traversing the universe.  Do not insist upon arguing your case before a judge, because this reasoning would probably get you into more hot water and you would end up paying a stiffer fine.  Add to that your court costs and attorney fees.

There probably are specially-constructed jail cells in the “slammer” ready for foolish drivers who want to make inane little remarks that would probably be over the heads of their local traffic enforcement officers.  So be silent, take the ticket, take your medicine, and shut up!  And forget that I ever mentioned this subject.

NOTE:  All calculations in this article are in “metric” units, in somber memory of the recent Mars Climate Orbiter tragedy.

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This page originally appeared in Reflections of the University Lowbrow Astronomers (the club newsletter).
This page revised Sunday, March 9, 2014 4:30 PM.
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