arXiv subjects

Eric Baird

Publications and source records attributed to Eric Baird.

13 recordsLinked to original sources

arXiv2001

The "optical" version of the barn-pole problem

We present diagrams and simple calculations for the apparent (i.e. photographable) length of a moving ruler skimming the observer's position, under three different classes of model. Special relativity's predictions in this particular situation are the root-product average of the two more basic first-order predictions generated by simple "propagation timelag" arguments. We find that special relativity can legally predict either a photographable Lorentz contraction or a photographable Lorentz expansion in the "centred" ruler, depending on whether our camera is at the ruler's "apparent" or "official" centre.

physics.gen-ph↗

arXiv2001

Problems with "GR without SR: A gravitational-domain description of first-order Doppler effects" (gr-qc/9807084)

Einstein's goal of producing an advanced gravitational model that was independent of special relativity's "non-gravitational" derivations has arguably still not been achieved. The author produced a paper in 1998 outlining a possible method of attack on the problem based on shift equivalence principles ("Doppler mass shift"). Some problems with this paper have since come to light. We list some further developments, some papers not cited in gr-qc/9807084, some experimental results missed by the author, and identify a problem with the paper's approach to aberration effects.

physics.gen-ph↗

arXiv2000

Newton's aether model

Isaac Newton is usually associated with the idea of absolute space and time, and with ballistic light-corpuscle arguments. However, Newton was also a proponent of wave/particle duality, and published a "new" variable-density aether model in which light and matter trajectories were either bent by gravitational fields, or deflected by an aether density gradient. Newton's (flawed) aether model can be considered as an early attempt at a curved-space model of gravity.

physics.gen-ph↗

arXiv2000

Transverse redshift effects without special relativity

Transverse redshift effects are sometimes presented as being unique to special relativity (the "transverse Doppler effect"). We argue that if the detector is aimed at 90 degrees in the laboratory frame, most theories will predict a redshifted frequency at the detector, although these predictions can be concealed by specifying that angles should be defined in a frame /other/ than the laboratory frame. These redshifts are often stronger than special relativity's predictions. We list some of the situations in which lab-transverse redshifts would be expected.

physics.gen-ph↗

arXiv2000

Relativistic angle-changes and frequency-changes

We generate a set of "relativistic" predictions for the relationship between viewing angle and apparent frequency, for each of three different non-transverse shift equations. We find that a detector aimed transversely (in the lab frame) at a moving object should report a redshift effect with two out of the three equations.

physics.gen-ph↗

arXiv2000

Two exact derivations of the mass/energy relationship, E=mc^2

The E=mc^2 relationship is not unique to special relativity. Einstein published one exact derivation from special relativity and two approximate derivations that used general extensions to Newtonian mechanics, and an exact derivation is also possible if we use a "first-order" Doppler equation instead of special relativity's "relativistic Doppler" formula. We present two sample derivations based on different non-transverse Doppler relationships, and briefly look at the two diverging systems of physics that result.

physics.gen-ph↗

arXiv1999

Warp drives, wavefronts and superluminality

Coule's primary objection to the Alcubierre "warpdrive" is that the material producing the warp field needs to be superluminal. This difficulty is solved by placing the drive material inside its own warp field (making the drive system part of the payload), but we then have to deal with Low's related objection, that there is then a restricted rate at which this "naked" warp-field can propagate through the background metric. We argue that the propagation of this sort of gravitational wave is not a trivial problem, and that the possibility of ultrafast warpfield propagation should not be dismissed without further research.

physics.gen-ph↗

arXiv1999

Hyper-fast travel without negative energy

Olum (PRL 81 3567-3570, 1998) has defined "superluminality" as the ability of a signal path to carry information faster than any neighbouring signal path, and has suggested that this requires a negative energy-density. However, this condition can be created without exotic matter if we are only sending information along the delivery path in one particular direction, and restrict ourselves to experiments that do not involve the speed of any counterpropagating or return-trip signals. Although negative energy-densities may be required for enhanced transit speeds in both directions along a single path at the same time, a traveller will normally not need (or want!) to travel in two opposing directions at once, so the condition of bidirectionality that gives rise to the negative energy condition may be unnecessarily restrictive.

gr-qc↗

arXiv1998

The light speed barrier: Bending the rules

Special relativity includes a concealed mechanism for reducing time-dilation effects in two mutually-receding objects. Forwarding their signals via one or more intermediate physical relay stages (a "probe chain") allows enhanced communication and propulsion efficiency. These possibilities are masked by the mathematical redefinitions of the special theory, which then assigns the velocity of the signal source a correspondingly lower value by using a velocity-addition formula. Probe chains reveal the existence of velocity-dependent curvature within inertial systems, and suggest a mechanism for indirect radiation from black holes that is strongly reminiscent of Hawking radiation. The "emitter-theory" force law is mentioned as a possible basis for a curved-space alternative to special relativity.

gr-qc↗

arXiv1998

Ruler-changes and Relative Velocity

Simple signal-propagation effects make receding objects seem contracted and approaching objects seem elongated. These effects are theoretically photographable, and are proportional in strength to the frequency-change in the object's emitted light. In a one-dimensional version of the "barn-pole" experiment, a "moving" object's photographed image can appear doubly length-dilated according to fixed-aether theory, but only singly length-dilated according to SR. This expected difference might be charitably described as a form of photographable Lorentz contraction.

physics.ed-ph↗

arXiv1998

GR without SR: A gravitational-domain description of first-order Doppler effects

Equivalence principles are a major part of modern relativity theory. Gravitational shifts can already be calculated within the time domain as motion shifts, and we examine the consequences of reversing this argument and describing motion shifts outside the time domain, as effects of curvature associated with relative velocity. This unusual "Doppler mass shift" approach appears to resolve some of Einstein's own criticisms of the "SR+GR" model and seems to remove some barriers to the reconciliation of classical and quantum theory. The disadvantage of this model is that constant-velocity problems no longer obey Euclidean geometry. By bypassing special relativity and the special theory's flat-space assumptions, the model also suggests an alternative non-transverse frequency-shift relationship. This difference should be testable.

gr-qc↗

arXiv1998

Superluminality and Pair-Production

When an information-carrying lightbeam is (legally) swept across a surface at more than c, simple signal-propagation arguments allow the observed behavior of the moving image (or "sprite") to include time-reversal and pair-production effects. A pair-production description also arises if we try to impose some common assumptions of general relativity onto the physics of an indirectly-radiating Eighteenth-Century "dark star". This result seems suspiciously similar to the modern concept of "Hawking radiation".

physics.ed-ph↗

arXiv1998

Aberration and Special Relativity

Section 7 of Einstein's 1905 electrodynamics paper gives frequency-shift and aberration formulae that together describe an elongated ellipsoidal wavefront. A Lorentz contraction of this ellipsoid solves most (but not all) of the associated relativistic problems.

physics.ed-ph↗