<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="font-family:arial,sans-serif">On Thu, Nov 16, 2017 at 11:32 PM, 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"><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>How do you know there was a first moment of time?</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 that, but I do know if there was a first moment of time then it would be silly to talk about paths leading up to it.</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>If any observer can use that space-time interval to calculate what any<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>other observer sees, that is in effect, universal agreement.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">So if I say your clock is running </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">slow and you say my clock is running slow we are in agreement? Which event do we agree happened first, event X or event Y? At the end of the day do we both agree that I turned out to be wrong or do we both agree that you turned out to be wrong?</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">
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<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>If that is not universal agreement, </blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4">It isn't.</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>then what is?<br></blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4">We both agree that your clock was running slower than mine. And that is what would happen if you revered your velocity and came back and we placed the two clocks side by side and we both looked at them.</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>But those who disagree on which<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>happened first can't ever communicate with one another, though, because<br>
they are in different causal cells.<br></blockquote><div><br></div><div><div class="gmail_default"><font face="arial, helvetica, sans-serif"></font><font size="4">No, we were never moving faster than light so we can communicate again. We're both moving apart and we both see the other person's clock running slow, but then you turn around and come back and now we're back at the same place and we're not moving with respect to each other anymore and we both find that our two clocks do not agree, we both agree your clock ran slow, mine says 3 o'clock but yours says 2 o'clock. There is no paradox because the symmetry has been broken, you accelerated but I did not, if you're accelerating (or equivalently in a strong gravitational field) you will see my clock running fast and I will see your clock running slow. </font></div></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">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>If there are always at least two observers for which energy is conserved<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> [....]</div></blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">When looking at the largest scale no observer will ever see energy conserved in a accelerating universe.</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"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>there must be places where the big bang has not yet happened.</blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4">Places? The Big Bang was the origin of places, before the Big Bang there were no places, at least not in our observable universe.</font></div></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"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>The<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>only other alternative is that it is simultaneously happening everywhere<br></blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"></div><font size="4">If the Big Bang was the beginning of time then it was simultaneous because no other time existed when it could have happened, and it happened everywhere because it was the beginning of space so there was no other place it could have happened.</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">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>in an infinite universe, big bangs are as common as you are.<br></blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">Yes I agree, but if they exist those places</div> <div class="gmail_default" style="display:inline"><font face="arial, helvetica, sans-serif">really are causally disconnected from 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>But we would both agree on how much fuel you used to get here no matter<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>when you hit the accelerator or the brake. Which is what we are<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>discussing. The conservation of energy.<br></blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">The conservation of energy still works fine at small scales, a million light years or so, but not at cosmological distances. </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"><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>why the universe was decelerating for the first 9 billion<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>years of its existence and only started accelerating 5 billion years ago.</font></blockquote>
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<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">> </div>It's because the rate of expansion of space-time in our causal cell is<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>linked to the rate of matter creation in our causal cell. But they balance<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>each other out because<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>the negative energy of that all that curved<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>space-time exactly cancels out all the positive mass-energy.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">But things are not balanced out and never have been, if they were the universe would be expanding at a constant rate but instead it was slowing down for the first 9 billion years and then sped up for the next 5 billion. And that what you'd expect if matter, which wants to slow things down, was becoming more dilute as more space was created but Dark Energy, which wants to speed things up, was not becoming more dilute because it is a property of space itself. </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"><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> <font size="4">I don't insist on matter being conserved but not energy, but for the last 20 years we've have lots of empirical evidence that the universe does<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>insist on exactly that. As to why the universe prefers things that way<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>you'll have to ask the universe not me</font>.</blockquote>
</blockquote><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></blockquote><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>But the mass-energy equivalence principle makes that paradoxical. If you<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>can convert matter into energy and vice-versa, then that means that matter<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>cannot be conserved or energy must be conserved. You can't have it both<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>ways.</blockquote><div><br></div><font size="4">Water and steam can be converted from one to the other but that doesn't mean the laws of physics treat the two things the same way. Einstein said matter and energy can be converted from one to the other but he certainly did not say they always are converted or that the two things <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">are </div>identical. The amount of matter in the universe, both dark and regular, has remained almost constant since the Big Bang, but the amount of Dark Energy has increased<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>and its increased by a lot<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">. The amount of matter and Dark energy has changed and that's </div>why<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> the expansion the expansion rate has also changed.</div></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>If the number of particles increases, and their rest masses are conserved,<br></blockquote><div><font size="4"><br></font></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4">Then each individual particle must have less mass than before. </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>Why is the negative energy density of dark energy i.e. negative<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>pressure or tension assigned a positive mass such that it accounts for 68%<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>of the universe's mass?<br></blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><font size="4">We know that there is about 5 times more Dark Matter than regular matter and we know that all matter has mass or it wouldn't be matter. Energy has no rest mass but matter does and that means it takes energy to accelerate it, and something is accelerating all that matter and the energy required to do that would be about twice as much as energy equivalent of all that matter, dark and regular combined. </font></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="font-family:arial,sans-serif"> </span><br></div></div></div></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><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">
> when 3 protons fuse they produce 4 particles, a positron a neutrino a<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div> gamma ray and a Helium-3 nucleus, but the number of particles is<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>irrelevant from a cosmological perspective, but the total mass/energy is</font></blockquote></div></div><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"> not and the fusion process does not change that.</font></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>I am suggesting it is not irrelevant. 4 particles far apart bend spacetime<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>differently than 3 particles close together.</blockquote><div><br></div><div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4">The 4 particles bend spacetime less than the 3 particles did because there is less mass, the gamma ray has no rest mass but it took rest mass to create it in the fusion process. </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>A flat or negatively curved infinite universe can expand and even<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>accelerate indefinitely.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">It can expand </div>indefinitely</font><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><font size="4"> but you can't deduce acceleration from geometry alone, you need energy for that. </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>If it is flat, then Freidmann demonstrated that<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>Einstein's theory predicts that energy is conserved.<br></blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"></div>And Freidmann did not predict a<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">n</div> accelerating universe nor did anyone else, it came as a great shock to everyone, its still not understood worth a damn and that's why its called dark. It's been known for a long time from the laws of Quantum Mechanics that empty space should have energy, but the calculated value was HUGE, about 10^120 times larger than what we actually see. If it were really that big the universe would blow itself apart a nanosecond after the Big Bang. Physicists weren't too worried about that because they figured eventually they'd figure out a way to cancel things out and the true value <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">would be</div> zero. But now with the discovery of a accelerating universe they must figure out how to cancel everything out EXCEPT for one part in 10^120, a far more difficult task.<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> Dark Energy is the greatest mystery in physics, even stranger than Dark Matter.</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>Dark matter is probably black holes</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">That would be my best guess too but I could be wrong.</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>In a Dark Energy-dominated universe what's the point of having any matter<br>
at all?</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">I don't think the universe has a point, but people do.</div> </font></div><div><br></div></div></div><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>The number of particles *is* relevant. The gravitational field stores<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>energy.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">It can convert kinetic energy to potential, but in fusion the kinetic energy itself had to come from someplace and that would be the rest mass of the original particle, so I don't see the point of considering it. </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"><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"> it's outside our light-cone so we can<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>never know. </font></blockquote>
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But with gravity you can detect things you can't see.</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">If something is outside our light cone it can't effect us and we can't effect it, not by by gravity and not by anything else that moves at the speed of light or less.</div> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">And everything moves at the speed of light or less.</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"> It's how we detected<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>the planet Neptune by how it perturbed the orbit of Uranus</blockquote><div><br></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">Neither Neptune nor Uranus is outside our light cone. And we can see Neptune we just didn't know where to look.</div> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"></div></font></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><br></div></font></div><div><font size="4"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> John K Clark</div></font></div><div><font size="4"><br></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"><br></blockquote></div></div></div>