<html>
  <head>
    <meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
  </head>
  <body bgcolor="#FFFFFF" text="#000000">
    On 2016-05-24 01:33, John Clark wrote:<br>
    <blockquote
cite="mid:CAJPayv1r4FYa11PmH7d6TDrPBvGCw755ANSAZF=TskD_SZr+Zg@mail.gmail.com"
      type="cite">
      <div dir="ltr">
        <div class="gmail_extra">On Mon, May 23, 2016 at 2:57 PM, Anders
          Sandberg <span dir="ltr"><<a moz-do-not-send="true"
              href="mailto:anders@aleph.se" target="_blank">anders@aleph.se</a>></span>
          wrote:
          <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 bgcolor="#FFFFFF" text="#000000"><span class=""> O
                  <div class="gmail_default"
                    style="font-family:arial,helvetica,sans-serif;display:inline">​
                    ​</div>
                  n 2016-05-23 19:19, John Clark wrote:<br>
                  <div dir="ltr">
                    <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>
                        We know from the percentage of the  elements
                        Hydrogen, Deuterium, Helium and  Lithium  how
                        much regular matter was around one minute after
                        the Big Bang when nucleosynthesis cooked up
                        these elements, and there is no room for Dark
                        Matter.</font></blockquote>
                  </div>
                </span></div>
            </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"> </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 bgcolor="#FFFFFF" text="#000000"><span class="">
                  <div dir="ltr"> </div>
                </span>
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​>
                  ​</div>
                Huh? Can you unfold how the nucleosynthesis data doesn't
                fit dark matter? Last time I checked the literature
                (fall last year) there was a fairly decent parameter
                window of the nuclei/DM parameter space, where lithium
                abundance was used as a sensitive constraint on the
                properties of DM. <br>
              </div>
            </blockquote>
            <div><br>
            </div>
            <div><font size="4">
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​</div>
                The present
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​ </div>
                lithium
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​and
                  Helium ​</div>
                abundance
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​
                </div>
                gives a tight constraint on the amount of normal
                baryonic matter (matter made from electrons neutrons and
                protons) that
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​could
                  have ​</div>
                existed at the time of  nucleosynthesis
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​,
                  and there is not nearly enough of it to account for </div>
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">Dark
                  Matter. So whatever Dark Matter is it can not be
                  normal ​</div>
                baryonic matter
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​,​</div>
                <div class="gmail_default"
                  style="font-family:arial,helvetica,sans-serif;display:inline">​
                  and it can't be made of Stellar Black Holes</div>
              </font></div>
          </div>
        </div>
      </div>
    </blockquote>
    <br>
    So how does this rule out WIMPs? In fact, if I understand the models
    right, WIMPs are much better at explaining halo shapes than MACHOs.
    While it might be annoying to posit some new weakly interacting
    particle, there is ample precedent for them existing (neutrinos) and
    they sometimes show up because of other theories (axinos and Susy).
    It seems a bit premature to immediately latch on to black holes.<br>
    <br>
    Although it does indeed nicely explain that early black hole. Of
    course, we should be able to figure out a frequency distribution of
    early too large holes from this theory and check it. <br>
    <br>
    <pre class="moz-signature" cols="72">-- 
Dr Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University</pre>
  </body>
</html>