All articles with the Diagrams tag

Abrupt climate change

Posted July 19th, 2009 in Physics. Tags: , , , , , , .

One part of a recent survey caught my attention:

The strongest correlate of opinion on climate change is partisan affiliation. Two-thirds of Republicans (67%) say either that the Earth is getting warmer mostly because of natural changes in the atmosphere (43%) or that there is no solid evidence the Earth is getting warmer (24%). By contrast, most Democrats (64%) say the Earth is getting warmer mostly because of human activity. … The divide is even larger when party and ideology are both taken into consideration. Just 21% of conservative Republicans say the Earth is warming due to human activity, compared with nearly three-quarters (74%) of liberal Democrats. [Pew Research Center] (Skip to videos, data, index.)

In other words, most of the general public appears to believe that the existence of abrupt climate change A large-scale change in the climate system that takes place over a few decades or less, persists (or is anticipated to persist) for at least a few decades, and causes substantial disruptions in human and natural systems. (formerly known as anthropogenic ‘Human-caused’ global warming) is a question of politics rather than science. (more…)

Any FTL signal can be sent back in time

Posted October 27th, 2008 in Relativity 2. Tags: , , , .

One surprising consequence of Einstein’s special theory of relativity is that any signal traveling faster-than-light (FTL) can be used to send a message to the past. Special relativity divides the entire universe into three distinct regions as seen by any observer: (more…)

Climate destabilization

Posted April 7th, 2012 in Physics. Tags: , , , , , , .

The overwhelming majority of scientists endorse this statement:

“Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.” [IPCC Summary for Policymakers, 2007]

Here, “most” means at least 50% of the 0.55°C rise since 1950. Some mistakenly call this an “alarmist exaggeration” but it actually understates the human contribution because it’s easy to incorrectly conclude that the other 50% of the trend might be caused by natural forcing variations: (more…)

Crash course on climate change

Posted February 9th, 2013 in Science. Tags: , , , , , , .

Before the Industrial Revolution in the 1800s, the concentration of carbon dioxide (CO2) in the atmosphere was about 280 parts per million (ppm). This means that for every million molecules in the atmosphere, about 280 of them were CO2.

However, shows that we’ve burned so much coal and oil that atmospheric CO2 is now approaching 400 ppm. It hasn’t been this high for millions of years. The last time Earth’s atmosphere had this much CO2, our species (and many others) hadn’t yet evolved. (more…)

Quantum teleportation

Posted October 28th, 2008 in Quantum 3. Tags: , , , .

Teleportation, a term originally coined by science fiction, refers to a hypothetical technology that can transport objects (or, eventually, people) nearly instantaneously from one location to another without sending the object through the intervening space. Classically, one might approach this problem by attempting to record the states of all the particles constituting the object to be teleported; that information could then be transmitted to a distant receiver and used to reconstitute the object out of raw materials available at the receiver. For many years this approach to teleportation was considered implausible because of quantum mechanical concerns. For instance, a teleportation device must somehow record the precise positions and momenta of all atoms in an object in order to reconstruct the object on the other side. This simultaneous measurement of non-commuting observables is forbidden by the uncertainty principle. A more fundamental problem exists, though, which is evident even in situations where the uncertainty principle is not directly applicable. To illustrate this point, consider the teleportation of a (more…)

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