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Two other points worth noting: Shortly after the Big Bang there was a perio=
d of cosmic inflation. This was originally an entirely theoretical concept =
to deal with issues such as why is the universe so flat. and the horizon pr=
oblem (how can the cosmic microwave background be almost exactly the same i=
n opposite directions when there has not been enough time in the universe f=
or them to have been in contact with each other. Cosmic inflation, which no=
w has some observational evidence to back it up, was a brief period when th=
e size of the universe expanded exponentially, and much faster than the spe=
ed of light. This is not a problem as relativity theory does not prohibit s=
pace-time from expanding faster than the speed of light. Cosmic inflation c=
arried the vast majority of the universe so far from us that its light has =
not yet reached us. Thus, the term "observable universe". At the end of the=
cosmic inflationary period, the expansion took on the rate that we see now=
(less the effects of mass slowing it and dark energy accelerating it.
It is also worth noting that special relativity deals only with the speed o=
f light. For the universe to be logically consistent, all observers, regard=
less of their relative motion (hence the term "relativity") see the speed o=
f light in a vacuum as the "speed of light". As Carl Sagan said, Thou shalt=
not add the speed to the speed of light. Special relativity is what makes =
strange things appear to happen to other observers as you near the speed of=
light. Your clocks (biological and mechanical) slow down, you contract in =
length in the direction of travel, and your mass increases. Unless you are =
making really precise measurements, such as with an atomic clock or the GPS=
satellites, these effect do not really start to show up until you get near=
50% of the speed of light. At "human" speeds, the equations simplify to Ne=
wton's laws of motion. When you add gravity to special relativity you get g=
eneral relativity, which, when Einstein first worked it out, had him puzzle=
d as it predicted that the universe should be either expanding or contracti=
ng! General relativity also says that "gravity" is the warping of space-tim=
e caused by the presence of mass. All moving objects, including light respo=
nd to the warping of space-time by changing their velocity, so that even li=
ght, passing near a massive object, will change direction. This effect is r=
esponsible for gravitational lenses. (https://en.wikipedia.org/wiki/Gravita=
tional_lens) Some exoplanets have been found using gravitational lens.
Pat
On Feb 25, 2019, at 2:08 PM, Larry Bogan wrote:
David,
Maxwell's equations summarize the laws of electric and magnetic fields. Th=
eir solutions for an oscillating electric charge describes the electromagne=
tic wave (light, radio, xray, microwave, etc) and in the solution the speed=
of those waves in a vacuum is determined by two constants, the permittivit=
y and permeability of free space. These two constants are determined separa=
tely by the laws of electric and magnetic fields.
All this was known in the late 19th century.
https://en.wikipedia.org/wiki/Maxwell%27s_equations
--
Larry Bogan
<larry@bogan.ca>
Brooklyn Corner, Nova Scotia
On Mon, 25 Feb 2019 14:22:37 +0000
David <dwebster@glinx.com> wrote:
Hi Burkhard, Lois, Don & All,
The more I hear about the big bang, which seems to be heavy on
speculation and light on certainty, the more I am inclined to turn to
the present and try to understand it.
One puzzle to which I have found no clear answer is a statement in a
text on Electricity and Magnetism (G.R. Noakes,1950); (page 322) that
ratios of such measurements as capacity in electromagnetic units and
capacity in electrostatic units is "...the simplest direct way of
determining c, the speed of light. It would be inconvenient to do so but
this suggests that the speed of light (in air ?) could be measured in
the dark.
Does this imply that c is determined by the interaction of
electrostatic and electromagnetic forces (possible because light waves
involve both) or is this just a coincidence of ratios between two
independently developed systems of measurement ?
YT, DW, Kentville
Patrick Kelly
159 Town Road
Falmouth NS B0P 1L0
Canada
(902) 472-2322
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Two other points worth noting: Shortly after the Big Bang there was a perio=
d of cosmic inflation. This was originally an entirely theoretical concept =
to deal with issues such as why is the universe so flat. and the horizon pr=
oblem (how can the cosmic microwave
background be almost exactly the same in opposite directions when there ha=
s not been enough time in the universe for them to have been in contact wit=
h each other. Cosmic inflation, which now has some observational evidence t=
o back it up, was a brief period
when the size of the universe expanded exponentially, and much faster than=
the speed of light. This is not a problem as relativity theory does not pr=
ohibit space-time from expanding faster than the speed of light. Cosmic inf=
lation carried the vast majority
of the universe so far from us that its light has not yet reached us. Thus=
, the term "observable universe". At the end of the cosmic inflat=
ionary period, the expansion took on the rate that we see now (less the eff=
ects of mass slowing it and dark energy accelerating
it.
<div><br>
</div>
<div>It is also worth noting that special relativity deals only with the sp=
eed of light. For the universe to be logically consistent, all observers, r=
egardless of their relative motion (hence the term "relativity") =
see the speed of light in a vacuum as the
"speed of light". As Carl Sagan said, Thou shalt not add the spe=
ed to the speed of light. Special relativity is what makes strange things a=
ppear to happen to other observers as you near the speed of light. Your clo=
cks (biological and mechanical) slow down,
you contract in length in the direction of travel, an