Tag Archives: Universe

Do we matter in the cosmos?

By Nick Hughes – By recent estimates, the Milky Way is just one of 2 trillion galaxies in the observable Universe, and the region of space that they occupy spans at least 90 billion light-years.

If you imagine Earth shrunk down to the size of a single grain of sand, and you imagine the size of that grain of sand relative to the entirety of the Sahara Desert, you are still nowhere near to comprehending how infinitesimally small a position we occupy in space.

And that’s just the spatial dimension. The observable Universe has existed for around 13.8 billion years. If we shrink that span of time down to a single year, with the Big Bang occurring at midnight on 1 January, the first Homo sapiens made an appearance at 22:24 on 31 December. It’s now 23:59:59, as it has been for the past 438 years, and at the rate we’re going it’s entirely possible that we’ll be gone before midnight strikes again.

In the grand scheme of things we are very, very small. more> https://goo.gl/Dp2NaC

The idea of creating a new universe in the lab is no joke

By Zeeya Merali – There’s an established principle in quantum theory that pairs of particles can spontaneously, momentarily pop out of empty space. Alex Vilenkin took this notion a step further, arguing that quantum rules could also enable a minuscule bubble of space itself to burst into being from nothing, with the impetus to then inflate to astronomical scales.

Our cosmos could thus have been burped into being by the laws of physics alone. Many cosmologists have made peace with the notion of a universe without a prime mover, divine or otherwise.

.. flipping the problem around, I started to wonder: what are the implications of humans even considering the possibility of one day making a universe that could become inhabited by intelligent life? As I discuss in my book A Big Bang in a Little Room (2017), current theory suggests that, once we have created a new universe, we would have little ability to control its evolution or the potential suffering of any of its residents. Wouldn’t that make us irresponsible and reckless deities?

We will not be creating baby universes anytime soon, but scientists in all areas of research must feel able to freely articulate the implications of their work without concern for causing offence. Cosmogenesis is an extreme example that tests the principle.

Parallel ethical issues are at stake in the more near-term prospects of creating artificial intelligence or developing new kinds of weapons, for instance.

As Anders Sandberg put it, although it is understandable that scientists shy away from philosophy, afraid of being thought weird for veering beyond their comfort zone, the unwanted result is that many of them keep quiet on things that really matter. more> https://goo.gl/GjCJpd

Why things happen

BOOK REVIEW

The Direction of Time, Author: Hans Reichenbach.
Time’s Arrow, Author: Martin Amis.

By Mathias Frisch – Common-cause inferences are so pervasive that it is difficult to imagine what we could know about the world beyond our immediate surroundings without them.

Astronomical observations provide a particularly stark example. How do we know that the points of light in the night sky are stars?

The approach using laws and initial (or, in this case, final) conditions to calculate backward in time to the existence of the star would require data on the surface of an enormous sphere of possibly many light years in diameter.

Stuck here on Earth as we are, that just isn’t going to happen. So what do we do?

Well, we can make use of the fact that we observe points of light at the same celestial latitude and longitude at different moments in time, or at different spatial locations, and that these light points are highly correlated with one another. (These correlations can, for example, be exploited in stellar interferometry.)

From these correlations we can infer the existence of the star as common cause of our observations. Causal inference may be superfluous in some idealised, superhuman version of physics, but if you actually want to find out how the Universe works, it is vital. more> https://goo.gl/mGuqhX

New model of cosmic stickiness favors ‘Big Rip’ demise of universe

By Vanderbilt University – The universe can be a very sticky place, but just how sticky is a matter of debate.

That is because for decades cosmologists have had trouble reconciling the classic notion of viscosity based on the laws of thermodynamics with Einstein’s general theory of relativity. However, a team from Vanderbilt University has come up with a fundamentally new mathematical formulation of the problem that appears to bridge this long-standing gap.

The new math has some significant implications for the ultimate fate of the universe. It tends to favor one of the more radical scenarios that cosmologists have come up with known as the “Big Rip.” It may also shed new light on the basic nature of dark energy.

The new approach was developed by Assistant Professor of Mathematics Marcelo Disconzi in collaboration with physics professors Thomas Kephart and Robert Scherrer. more> http://tinyurl.com/q9lp9ep

Do we live in a computer simulation?

R&D Magazine – A decade ago, a British philosopher put forth the notion that the universe we live in might in fact be a computer simulation run by our descendants. While that seems far-fetched, perhaps even incomprehensible, a team of physicists at the University of Washington has come up with a potential test to see if the idea holds water.

“If you make the simulations big enough, something like our universe should emerge,” Martin Savage said, a University of Washington physics professor. Then it would be a matter of looking for a “signature” in our universe that has an analog in the current small-scale simulations. more> http://tinyurl.com/cpcgvys