Physics: What We Do and Don’t Know

The article author is Steven Weinberg:<p><a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1979/weinberg-bio.html" rel="nofollow">http:&#x2F;&#x2F;www.nobelprize.org&#x2F;nobel_prizes&#x2F;physics&#x2F;laureates&#x2F;197...</a><p>The Nobel Prize in Physics 1979 with Sheldon Glashow and Abdus Salam &quot;for their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current&quot;.<p>The article is fantastically clear, with much less mystification than in ordinary physics popularization articles.

That photo of the Hubble Deep Field really messes with me... in fact any photo like that. You have to realise: somewhere out there, in fact, most likely, many, many places out there, are planets where everything we have and will experience has already happened. Whatever end-point human evolution is driving towards (massive environmental degradation, simulacrum-building, rise of a superhuman elite, space-travel, true self-knowledge, total mastery over the physical world, whatever) - its already happened. Over and over again. By people&#x2F;things we will never meet and never know about.<p>Feels very disheartening.

the article seems to be dated &quot;November 7 2013&quot;, nearly one month in the future. Clearly the author knows something about physics that we don&#x27;t.

A very insightful article. Once I started reading it, I got hooked. I started searching for references on Wikipedia etc. Now I want to become a Physicist.

&quot;Oddly, little attention was given to an obvious conclusion: if the galaxies are rushing apart, there would have been a time in the past when they were all crunched together. &quot;<p>I still find this hard to swallow - whilst its obvious as a conclusion, it also feels like it has obvious flaws. Can we not get exactly the same effect from a large universe in which new space and matter is formed in the voids? and don&#x27;t we need to understand the &#x2F;actual&#x2F; creation of space and matter in totality (v.s. eg creation and annihilation of particles and other &#x27;bits of universe) - its an enormous gap in our understanding and a vital feature of a truly comprehensive theory...

So we&#x27;ve hit a wall in trying to understand how dark energy works or how its parameters arise. But I don&#x27;t think it&#x27;s logical or helpful to conclude that an anthropic explanation is the only option we have left. Maybe we just haven&#x27;t yet figured out the right questions to ask, that might open up a new field of investigation that could lead to new physics that provides a mechanism for how it works.<p>For example, we also still don&#x27;t understand the nature of dark matter. Even more fundamentally, we still don&#x27;t have a solid understanding of time, and why there is an apparent flow of time in one direction from the past to the future, or whether spacetime curvature induces quantum state collapse, or how the universe began with such low initial entropy.<p>Maybe discovering a deeper understanding of the foundations of the physics we&#x27;re already familiar with will open a way forward with understanding how dark energy works.

I found the article to be a good summation of work done over the last few hundred years.

I don&#x27;t like thinking about space too much; I mildly worry that if I get too much into it, something might snap in my head, and that can&#x27;t be a good thing.

great article but interesting to see it on the same day as the article about science moving sometimes in the wrong direction. for example string theory no: critical results. why string effort and not others? well a lot of people and a lot of effort went down that path it&#x27;s a simple as that: people. maybe there are other approaches, no doubt there are and that&#x27;s where the future will be

btw, Hubble Extreme Deep Field (2012) is deepest optical to date. &quot;The exposure time was two million seconds, or approximately 23 days&quot; [1] -- that&#x27;s insane stability!<p>[1] <a href="http://en.wikipedia.org/wiki/Hubble_Extreme_Deep_Field" rel="nofollow">http:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Hubble_Extreme_Deep_Field</a>

why does he say this &gt;&gt; &quot;early universe must have been very hot, or else all the hydrogen in the universe would have combined into heavier elements&quot;?.Hydrogen is still present and it is not so hot nowadays

&quot;...in the grim darkness of the far future there is only war.&quot;

How many neutrinos can you bench press?

What we don&#x27;t know: shit.