<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="font-family:arial,sans-serif">On Sat, Oct 14, 2017 Stuart LaForge </span><span dir="ltr" style="font-family:arial,sans-serif"><<a href="mailto:avant@sollegro.com" target="_blank">avant@sollegro.com</a>></span><span style="font-family:arial,sans-serif"> wrote:</span><br></div><div class="gmail_extra"><div class="gmail_quote"><br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Thermodynamics says that entropy is a function of state. That means it is<br>
path independent so it doesn't matter how the universe got into its<br>
initial state of zero entropy because all paths, including reversible<br>
ones, are equally valid.</blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4">All paths leading up to the first instant of time are equally invalid because there were none. </font></div> <br></div><div> <br></div></div></div><blockquote style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex" class="gmail_quote"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div> they don't agree,<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>some observers will say the universe is older than<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>others.</blockquote></div></div></blockquote><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>If that is the case, then of what use is the cosmological principle? </blockquote><div><br></div><div><font size="4"><span style="font-family:Roboto,arial,sans-serif;line-height:19.2px"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">You tell me. T</div></span>he cosmological principle<div class="gmail_default" style="display:inline"><font face="arial, helvetica, sans-serif"> says the universe looks the same at the largest scale, but it doesn't. Very distant galaxies near the limit of our cosmological horizon are smaller but have larger stars in them than galaxies that are closer to us.</font></div></font></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Why<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>even bother talking about the universe as some distinct entity unto itself<br>
that can have a definable age?<br></blockquote><div><font size="4"><br></font></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">Nothing has an age everybody can agree on, but that doesn't prevent anybody talking about stuff.</div> </font></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"></blockquote><br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><font size="4">
><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">></div> If a traveling<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div> observer goes from point A to point B the Proper Time of <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">t</div>hat journey is the time measured by the observers own stopwatch and using<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div> the traveling observer's definition of simultaneity to decide when to<br></font><font size="4">start and stop the stopwatch. But there is no universal agreement, some<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>observers will say the stopwatch is running too slow, others will say it<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>is too fast, and they will say the traveling observer started and stopped<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>the watch at the wrong time.</font></blockquote>
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<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">></div>But in the case of the universe, all those stop watches started at the<br>
same time and in the same place. </blockquote><div><br></div><div><div class="gmail_default"><font face="arial, helvetica, sans-serif"></font><font size="4"><font face="arial, helvetica, sans-serif">But to measure a time interval both a start and stop point is needed and </font></font><font face="arial, helvetica, sans-serif" size="4">all those stopwatches stopped at different times because there is no universal agreement on simultaneity, so there is no agreement on if watch X stopped before watch Y or watch Y stopped before watch X. And to make things even worse the stopwatches are running at different rates. S</font><span style="font-family:arial,helvetica,sans-serif;font-size:large">o there is no universal agreement on when the Big Bang happened; right here right now we say it was 13.8 billion years ago, but others would disagree </span></div></div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>They would have gotten out of synch over<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>the years due to local space-time curvatures but you should be able to<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>average all those stop watches together and get something like a "true<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>age" of the universe.<br></blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4">There are a infinite number of ways a bunch of distant clocks can be brought together in a expanding universe, and I don't see how everyone could agree on how to do it. Should distant clock X be brought to clock Y or should clock Y be brought to clock X? It makes a difference because one clock would be accelerated and the other clock would not and a accelerated clock runs slower than one in a inertial frame of reference. </font></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"> <br></div></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">></div> a flat universe can<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>conserve energy and that is thermodynamically satisfying.</blockquote><div><font size="4"><br></font></div><font size="4">A universe can be flat and still be <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">expanding and even </div>accelerating if there is a property of space itself that causes it to <div class="gmail_default" style="display:inline"><font face="arial, helvetica, sans-serif">intrinsically </font></div>contain energy, and we found out 20 years ago that there is, about 1/100 of a<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">n</div> erg per cubic meter. A erg is about as much energy as a common housefly needs to perform one push-up so that may not sound like much but there is a awful lot of otherwise empty cubic meters out there, so much so that today dark energy makes up 70% of the mass/energy in the entire universe. And that percentage will increase as time passes because both normal matter and dark matter will keep getting diluted but dark energy will not, the more space <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">that space itself creates </div>the more dark energy there is<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">,</div> but the amount of matter <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">in the universe </div>will be constant. </font><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>And the philosophical benefits of an infinite universe are also<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>satisfying. It would mean that we too are infinite with countless copies<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>repeated through time and space across the cosmos. Countless versions of<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>us living identical lives. Countless versions of us living every possible<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>permutation of our lives. Infinite copies of us taking every possible road<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>almost all of which are unique.<br></blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">I find that philosophically satisfying too, and maybe its true but the universe is under no obligation to conform to human desires. </div> </font></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
> ?From Sean Carroll at:<br>
> <a href="http://www.preposterousuniverse.com/blog/2010/02/22/energy-" rel="noreferrer" target="_blank">http://www.preposterousunivers<wbr>e.com/blog/2010/02/22/energy-</a><br><br><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Here Carroll makes it clear that he denies the conservation of energy to<br>
avoid having to explain negative energy to people. It's a pedagological<br>
choice he makes, not one based on mathematical reasoning.</blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4">The only reason humans invented conservation laws is to help us understand how the world works. If in circumstances far from everyday life we have to contort them in complex ways so they still apply then there gets to be a point where it's not worth the effort. The important thing is we </font></div><span style="font-size:large">can us the</span><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline"> </div><span style="font-size:large">mathematical reasoning</span><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline"> </div><span style="font-size:large">in </span><font size="4">Noether's theorem<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> to conclude that if the fundamental laws that tell objects how to move do not change with the passage of time then energy is conceived, but General Relativity says they do </div><font face="arial, helvetica, sans-serif">change </font><div class="gmail_default" style="display:inline">with the passage of time. I go back to my example of a gamma ray photon produced in the Big Bang, because something very fundamental has changes since that photon was produced, space has expanded, that gamma ray photon is now a far less </div>energetic microwave photon and eventually space will have expanded so much it will be a radio photon with a wavelength <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>longer than the observable universe and be undetectable even in principle. The energy in that photon would have been conserved if space didn't expand, but it does so it isn't. </font><br></div><div> <span style="font-family:arial,helvetica,sans-serif"></span></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>keep in mind that in a flat universe Dc is not just the critical<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>density of the universe but also the actual density of the universe.<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"></div></blockquote><div><br></div><div><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline"></div><span style="font-size:large">The equation you're using</span><span style="font-size:large">, Dc = 3H^2/(8*pi*G)</span><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline"> </div><span style="font-size:large">, </span><div class="gmail_default" style="font-size:large;display:inline"><font face="arial, helvetica, sans-serif">where Dc is the critical density </font></div><span style="font-size:large">is only valid if the cosmological constant is zero, but we've known for 20 years that i</span><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline">t</div><span style="font-size:large"> can't be zero because the universe is accelerating. So density alone doesn't determine geometry of the universe and </span><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline">thus we can't be living </div><span style="font-size:large">in a</span><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline"> simple</div><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline"> </div><span style="font-size:large">Friedmann universe</span><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline">.</div><br></div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>And H is only decreasing with time only if the density of the universe is<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>likewise decreasing with time.<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>But if the density of the universe is<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> i</div>ncreasing with time through conservation of energy</blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4">The density of normal matter and Dark Matter has decreased over time but it has become clear that the gravitation caused by matter alone (not even with the help of dark Matter) is insufficient to explain the evolution of the universe. For a very long time the expansion of the universe was slowing down just as you'd expect, but about 5 billion years ago (and nearly 9 billion year after the Big Bang) the deceleration stopped and things started to accelerate. This can only be because the matter became diluted and so did the gravitational force trying to slow things down but some property of space itself called Dark Energy which nobody understands causes things to speed up, so whatever it is when there is more space there is more Dark Energy </font></div><font size="4"> </font></div><div> <br></div></div></div><blockquote style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex" class="gmail_quote"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">>> </div>communicating is not the same thing as influencing, communicating<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div></font><span style="font-size:large"> involves transferring Shannon style information and </span><span style="font-size:large"> entanglement </span><span style="font-size:large">can't do that faster than light. But it will still let you influence</span><div class="gmail_default" style="font-size:large;font-family:arial,helvetica,sans-serif;display:inline"> </div><span style="font-size:large"> things faster than light.</span></blockquote></div></div></blockquote><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<br>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>Good. That's all my theory needs is for gravity to be able to "influence<br>
things" faster than light. No Shannon entropy need be exchanged.<br></blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4">But you also said:</font></div></div><div><font size="4"><br></font></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><i>"</i></div><i>In a flat<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>universe, dark energy is just superluminal gravity at long ranges</i><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">"</div><br></font></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4"><br></font></div></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4">I'm not sure what that means. If Dark Energy is a property of space itself as if seems to be then it doesn't need to travel a long distance to be manifest. </font></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>My earlier attempts at quantum gravity have been overturned by the<br>
super-long Compton wavelength of the graviton reported by LIGO.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">I don't know what you mean by that, LIGO has not detected the graviton nor has anybody else, it is purely theoretical and may not even exist and even if it does I think its unlikely anyone will be able to find one this century. </div> </font></div><div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>My equations simply lump pressure and tension together with matter density<br>and radiation density through the mass-energy equivalence principle. It<br>just deals with total density of all components of the stress-energy<br>tensor converted to mass.<br></blockquote></div><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4">Both pressure and tension are potential energy, but Einstein says pressure causes gravitational attraction but tension (negative pressure) causes gravitational repulsion.</font></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4"><br></font></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4"> John K Clark </font></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"></blockquote><br></div></div></div>