1.0Glossaryhttps://www.healthbenefitstimes.com/glossaryGlossaryhttps://www.healthbenefitstimes.com/glossary/author/adminglossary/rich600338<blockquote class="wp-embedded-content" data-secret="1tc2tlTKTR"><a href="https://www.healthbenefitstimes.com/glossary/nebular-hypothesis/">Nebular hypothesis</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://www.healthbenefitstimes.com/glossary/nebular-hypothesis/embed/#?secret=1tc2tlTKTR" width="600" height="338" title="“Nebular hypothesis” — Glossary" data-secret="1tc2tlTKTR" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script> /*! This file is auto-generated */ !function(d,l){"use strict";l.querySelector&&d.addEventListener&&"undefined"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-zA-Z0-9]/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),o=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),c=new RegExp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute("style"),"height"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new URL(s.getAttribute("src")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",function(){for(var e,t,s=l.querySelectorAll("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute("data-secret"))||(t=Math.random().toString(36).substring(2,12),e.src+="#?secret="+t,e.setAttribute("data-secret",t)),e.contentWindow.postMessage({message:"ready",secret:t},"*")},!1)))}(window,document); //# sourceURL=https://www.healthbenefitstimes.com/glossary/wp-includes/js/wp-embed.min.js </script> A theory of the formation of the Sun’s planetary system advanced by Pierre Simon Laplace (1749-1827) in his Exposition du Systeme du Monde (1796). He theorized that gravity would condense a rotating disc of matter with most of its mass near the center into a massive central body and a number of much smaller orbiting planets. The theory gave a plausible explanation of why all the planets orbit in the same direction and why their orbits are in approximately the same plane.In 1873, James Clerk Maxwell (1831-79) showed theoretically that radiation would exert a pressure on any surface on which it fell. This was confirmed experimentally in 1900. Sunlight, for example, is calculated to exert a pressure of about 2 pounds per square mile, so small as to be difficult to measure. But in the interior of stars and galaxies where the radiation intensity is much higher, radiation pressure is a significant factor. In 1900 two scientists in the University of Chicago showed that the Maxwell radiation pressure in a disc of the size required in the nebular hypothesis would counterbalance the gravitational forces and prevent condensation; they advanced an alternative theory. Sir James Jeans later showed that the radiation-pressure difficulty only held for astronomically small aggregations such as the solar system and that the nebular hypothesis could explain the condensation of stars from a galactic disc.