This article was interesting: https://www.popsci.com/where-are-aliens-new-model.

Looks like the second person in history who has been cured of AIDS (first one was twelve years ago) has happened.

I wonder if anybody has heard about research on a pair of binary supermassive black holes with self microlensing events periodically, from Kepler? Another microlensing event on the schedule for 2020. A nice fit to a light curve previously studied.

Gnargenox, source?

Well I don't consider Twitter a source for real info but it was by Dr. Jessie Christiansen on twitter.

If that pans out it will be enormously exciting.  I look forward to the paper!

It looks like Virgin Galactic did it again!


[youtube]CdgsdDZCEjg[/youtube]

From the video info:

Mojave, California, USA (22 Feb 2019): Today, Virgin Galactic conducted its fifth powered test flight and second space flight of its commercial SpaceShipTwo, VSS Unity. In its fifth supersonic rocket powered test flight, Virgin Galactic reached space for the second time today in the skies above Mojave CA. Spaceship VSS Unity reached its highest speed and altitude to date and, for the first time, carried a third crew member on board along with research payloads from the NASA Flight Opportunities program. This space flight means Chief Pilot Dave Mackay and co-pilot Michael “Sooch” Masucci become commercial astronauts and the 569th and 570th humans in space. Beth Moses, Virgin Galactic’s Chief Astronaut Instructor, flew as the third crew member in a first, live evaluation of cabin dynamics. She is the 571st person to fly to space and the first woman to fly on board a commercial spaceship.

In addition to this element of envelope expansion, VSS Unity flew higher and faster than ever before, as its world record-holding hybrid rocket motor propelled the spaceship at Mach 3.04 to an apogee of 295,007ft. The crew enjoyed extraordinary views of Earth from the black skies of space and, during several minutes of weightlessness while the pilots “feathered” the spaceship in preparation for a Mach 2.7 re-entry, Beth floated free to complete a number of cabin evaluation test points. The human validation of data previously collected via sensors, and the live testing of other physical elements of the cabin interior, are fundamental to the provision of a safe but enjoyable customer experience.

The glide back home was followed by a smooth runway landing and a rapturous reception from the crowd on the flight line, which included staff and some of Virgin Galactic’s 600 Future Astronaut customers.

Chief Pilot Dave Mackay, a born and bred Scotsman as well as an ex-RAF test pilot and Virgin Atlantic Captain, led his crew of newly qualified astronauts from VSS Unity accompanied by a kilted piper.

Sir Richard Branson said: “Flying the same vehicle safely to space and back twice in a little over two months, while at the same time expanding the flight envelope, is testament to the unique capability we have built up within the Virgin Galactic and The Spaceship Company organizations. I am immensely proud of everyone involved. Having Beth fly in the cabin today, starting to ensure that our customer journey is as flawless as the spaceship itself, brings a huge sense of anticipation and excitement to all of us here who are looking forward to experiencing space for ourselves. The next few months promise to be the most thrilling yet”.

PBS Spacetime did an interview with Richard Branson discussing the launch and possibilities for the public to go into space themselves using this technology:

[youtube]dWk9d_YCQOk[/youtube]

It looks like Virgin Galactic did it again!


[youtube]CdgsdDZCEjg[/youtube]

Very cute! I liked it!

What do you think guys about this? 
It seems like they "reversed time" on a quantum computer and they found out qubit (quantum computer's bits) returned to their initial state in the 85% of cases when they was two and 50% of cases when they was three.  

What do you think guys about this? 

Cool study, but some seriously bad explanation in the article.

Technology, helped by colleagues from Switzerland and the U.S inverted the flow of time for a quantum computer and an electron for a fraction of a second, contradicting the second law of thermodynamics, which says that a natural process runs only in one sense and is not reversible.

Neither of the underlined statements is correct.  This does not contradict the 2nd law, and many natural processes are reversible.   What the 2nd law says is that processes are (usually vastly) more likely to proceed in the direction that increases entropy.  But there are also reversible processes that do not change the entropy.  For example, the expansion of a universe filled with photons.  A more down-to-earth example is the Carnot cycle, which is built from four different reversible processes, two of which do not change the entropy and the other two which do by extracting heat and doing work.  It is also the most efficient way possible to extract useful energy from a thermodynamic system.

What they did here with the quantum computer is reverse the evolution of the system by "a time reversal".  For a classical example we can imagine a pool table.  Someone makes a good break, and immediately before the balls come to rest, we imagine perfectly reversing all of their velocities.  In practice this is obviously difficult to do, but it is simple enough in a computer simulation.  What happens is all the balls perfectly retrace their paths, come together and reform the rack, transferring all their momenta to the cue ball which then flies back to the stick.

What does the 2nd law have to say for this situation of reversing the break in pool?  After the break, the balls move to occupy more possible places in space on the table, as well as in momentum space (the momentum transfers from one ball to many, with each ball having a wide range of possible values of momentum after the collision).  Since many more possibilities exist after the break, the entropy increases, and therefore the 2nd law tells us this process should not be easily reversible.  We should not expect it to naturally happen in reverse, and by observation, it doesn't.

For a quantum system, the situation is more complicated.  The evolution is described by the Schrödinger equation, for which the results are probabilistic (we can't know exactly where an electron will be found in a measurement for example, but rather a set of probabilities for finding it at different locations), and the Schrödinger equation describes how those probabilities change over time.

For some simple case, we might imagine an electron confined inside a box.  Classically, we would image the electron as a particle bouncing regularly back and forth.  But quantum mechanically, it is a wave.  If we measure where the electron is, the wave immediately collapses to that location, indicating "the electron is right here".  But then it proceeds to spread out again according to the Schrödinger equation.  Another measurement made very quickly afterward may find the electron in nearly the same place, but after a lot of time it could be anywhere in the box, again with probability being related to the shape of the wave.  Furthermore, the greater the uncertainty in the momentum of the electron, the faster the wave will spread out, and likewise so too will the spread of uncertainty in where the next measurement will locate the electron.

With the evolution of qubits in a quantum computer, the time reversal and subsequent measurements must occur very quickly, or else that spread of uncertainty will result in the system not returning to its original state.  This is why there is not a 100% success rate, and lower for more qubits.

Yet another fine example of journalistic sensationalism.

[youtube]fpaxvjFh-qA[/youtube]

Was just going to post that.   Very interesting, and awesome that it was captured by 2 satellites!

What do you think guys about this? 

Cool study, but some seriously bad explanation in the article.

Technology, helped by colleagues from Switzerland and the U.S inverted the flow of time for a quantum computer and an electron for a fraction of a second, contradicting the second law of thermodynamics, which says that a natural process runs only in one sense and is not reversible.

Neither of the underlined statements is correct.  This does not contradict the 2nd law, and many natural processes are reversible.   What the 2nd law says is that processes are (usually vastly) more likely to proceed in the direction that increases entropy.  But there are also reversible processes that do not change the entropy.  For example, the expansion of a universe filled with photons.  A more down-to-earth example is the Carnot cycle, which is built from four different reversible processes, two of which do not change the entropy and the other two which do by extracting heat and doing work.  It is also the most efficient way possible to extract useful energy from a thermodynamic system.

What they did here with the quantum computer is reverse the evolution of the system by "a time reversal".  For a classical example we can imagine a pool table.  Someone makes a good break, and immediately before the balls come to rest, we imagine perfectly reversing all of their velocities.  In practice this is obviously difficult to do, but it is simple enough in a computer simulation.  What happens is all the balls perfectly retrace their paths, come together and reform the rack, transferring all their momenta to the cue ball which then flies back to the stick.

What does the 2nd law have to say for this situation of reversing the break in pool?  After the break, the balls move to occupy more possible places in space on the table, as well as in momentum space (the momentum transfers from one ball to many, with each ball having a wide range of possible values of momentum after the collision).  Since many more possibilities exist after the break, the entropy increases, and therefore the 2nd law tells us this process should not be easily reversible.  We should not expect it to naturally happen in reverse, and by observation, it doesn't.

For a quantum system, the situation is more complicated.  The evolution is described by the Schrödinger equation, for which the results are probabilistic (we can't know exactly where an electron will be found in a measurement for example, but rather a set of probabilities for finding it at different locations), and the Schrödinger equation describes how those probabilities change over time.

For some simple case, we might imagine an electron confined inside a box.  Classically, we would image the electron as a particle bouncing regularly back and forth.  But quantum mechanically, it is a wave.  If we measure where the electron is, the wave immediately collapses to that location, indicating "the electron is right here".  But then it proceeds to spread out again according to the Schrödinger equation.  Another measurement made very quickly afterward may find the electron in nearly the same place, but after a lot of time it could be anywhere in the box, again with probability being related to the shape of the wave.  Furthermore, the greater the uncertainty in the momentum of the electron, the faster the wave will spread out, and likewise so too will the spread of uncertainty in where the next measurement will locate the electron.

With the evolution of qubits in a quantum computer, the time reversal and subsequent measurements must occur very quickly, or else that spread of uncertainty will result in the system not returning to its original state.  This is why there is not a 100% success rate, and lower for more qubits.

Besides, there are different arrows of time, and the quantum arrow of time is bidirectional.

Not an April Fools joke.
https://www.eso.org/public/usa/announcements/ann19018/

Direct evidence for sudden KT extinction? Very interesting, though I've never liked the hypothesis that the extinctions happened in a few years rather than in millennia or even a million years.