What we undergrad students (at least I did for a long time) take for granted is that Bell’s inequality proofs there is for sure no deterministic theory of quantum mechanics. Is it really that “easy”? Maybe it’s pretty naive to accept the Copenhagen Interpretation without further thinking. Tim Maudlin who studied philosophy and physics at Yale University explains why we should consider less conventional “interpretations” of quantum physics.

You can find his corresponding paper here.


Ask Ethan: How Can A Nuclear Bomb Be Hotter Than The Center Of Our Sun?

“[T]he temperature in the core of our sun is usually cited at 15 million degrees Celsius or so. […] What I don’t get is this: some mid-sized thermonuclear test detonations done by the old Soviet Union and the USA have been recorded at (if only very briefly) 200 or even 300 million degrees Celsius. How can our pithy 3 stage hydrogen bomb blasts be so much hotter than the dense hell of the Sun’s monster fusion oven?”

The Sun, the greatest source of energy in our Solar System, converts a total of 700 million tons of mass into pure energy every second through the process of nuclear fusion. And yet, even in the hottest, densest, innermost part of the Sun, the temperature “only” reaches up to 15 million degrees. Somehow, on Earth, we’ve developed nuclear bombs that, despite having much, much smaller yields than anything occurring in the Sun, can exceed any temperature the Sun achieves. How is this possible? 

It’s not just about energy, but a whole slew of other conditions that make it happen. It’s true: nuclear bombs can out-heat the Sun. Here’s how.

NASA Mission To Set A ‘Depth Perception’ Record, And You Can Help

“By imaging two of the nearest stars to Earth from our planet and NASA’s New Horizons spacecraft, humanity will construct 3D images of the stars as though we had two eyes that were nearly 5 billion miles (8 billion kilometers) apart from one another. Not only will it spectacularly demonstrate how far NASA’s New Horizons has traveled, but it will give us a tiny glimpse into the humbling fact of our insignificant view of the cosmos.

We all know that the relative positions of stars that we see here on Earth are unique to our current perspective: our place in space and time. From any other vantage point, the stars and constellations would look dramatically different, as every solar system has a different night sky. For the first time, we’ll get to see the Universe with the depth perception of an unprecedented giant: one whose eyes are larger than the Sun-Pluto distance. The images, slated for release in May, will give us a view of the Universe as never before.”

Imagine what it would be like to have eyes that gave you superior depth perception than what we have today. They’d be separated by much larger distances than our faces allow, showing us how distant objects appear to move against the even-more-distant background ones as we switched between our left and right “eyes.” On April 22 and 23, 2020, NASA’s New Horizons mission will team up with amateur astronomers here on Earth to produce the longest-baseline parallax measurements ever, showing us the Universe in 3D as never before.

Come learn what we’ll see, what it means, and how you can participate by helping measure Proxima Centauri and Wolf 359 at the same, critical time!

Ending ‘Social Distancing’ For COVID-19 Will Create A Worst-Case Scenario

“The most important takeaway is this: COVID-19 is deadly, at least thirty times as deadly as the flu, and spreads easily and rapidly through an unrestricted population. The way we all lived our lives and publicly interacted with one another prior to March of 2020 is not a safe or sustainable way to live today, at perhaps the most critical time in this pandemic. Self-isolating as much as possible, to a much greater degree than we’re doing at present, is the best course of action we can presently make.

But if we remove our social isolation measures now, when we should be maximizing them more than ever, we’ll see tens of millions of Americans infected by mid-to-late April, with a substantial percentage of them very likely to die. The worst-case scenario can still be avoided, but only if we all act responsibly, and in the interest of the public good, right now.”

This is the most critical time for slowing and stopping the spread of the novel coronavirus COVID-19. We should be considering a nationwide shelter-in-place order for the next 3-to-7 weeks, not considering lifting our social distancing recommendations.

The science is very clear, and you should understand it for yourself. Read on.

Brian Greene is going to do this new video series from tomorrow onwards – I think it’s worth it to check it out 🙂

Btw do you know why Brian Greene is an extraordinary cool physicist? Because he’s vegan 😉

This Is The One Symmetry That The Universe Must Never Violate

“In physics, we have to be willing to challenge our assumptions, and to probe all possibilities, no matter how unlikely they seem. But our default should be that the laws of physics that have stood up to every experimental test, that compose a self-consistent theoretical framework, and that accurately describe our reality, are indeed correct until proven otherwise. In this case, it means that the laws of physics are the same everywhere and for all observers until proven otherwise.

Sometimes, particles behave differently than antiparticles, and that’s okay. Sometimes, physical systems behave differently than their mirror-image reflections, and that’s also okay. And sometimes, physical systems behave differently depending on whether the clock runs forwards or backwards. But particles moving forwards in time must behave the same as antiparticles reflected in a mirror moving backwards in time; that’s a consequence of the CPT theorem. That’s the one symmetry, as long as the physical laws that we know of are correct, that must never be broken.”

Are the laws of physics the same, here and now, as they are at all other times and places in the Universe? If they are, then that means a certain symmetry exists. It appears, to up to 18 orders of magnitude in some experimental cases, that specific symmetry is good and respected by our Universe. If a theory demands its violation, that theory is presently unsupported by all of the evidence. The reason? 

One particular symmetry, known as CPT, that the Universe forbids us from violating.

Sorry, Stephen Hawking, But Every Black Hole Is Still Growing, Not Decaying

“It remains true that every black hole that exists in the Universe should emit Hawking radiation, and that if you wait long enough, all of these black holes will eventually decay. But in our Universe so far, based on the black holes that actually exist, not a single black hole has even begun to decay in a meaningful way. The amount and energy of the radiation that’s out there, from starlight and left over from the Big Bang, ensures that black holes will absorb it and grow much more quickly than they lose energy from radiating it away.

Even though it’s been more than 45 years since Hawking first figured out that black holes do emit radiation, as well as what that radiation must look like, it’s far too faint and sparse for us to have ever detected it. Unless there’s a surprisingly low-mass black hole or we’re willing to wait an enormous, cosmic time for the Universe to cool, we’ll never be able to see it. Black holes are growing, not decays, and astrophysics teaches us exactly why.”

Yes, black holes emit radiation of exactly the type described by Stephen Hawking: a low-energy spectrum of photons and other particles arising from the physics of quantum field theory in curved spacetime. But, for much longer, we’ve known that black holes must also be absorbing energy over time, from matter, from starlight, and from the cosmic microwave background radiation.

The results are in, and every realistic black hole in the Universe is growing, not decaying, and it isn’t even close.

10 Surprising Places In Space With The Right Raw Ingredients For Life

“Shortly after Earth first formed first formed, life quickly took hold, thriving ever since. Perhaps terrestrial life didn’t originate here, but arrived from elsewhere through natural processes. Surprisingly, the raw ingredients necessary for life exist almost everywhere astronomers look. Here are 10 locations where they’re ubiquitous.”

It’s not surprising to find that the ingredients for life are found in locations all over planet Earth. But what might be surprising is the sheer number and variety of places in the Universe, far beyond our planet, where the necessary raw ingredients are also found. I don’t just mean atoms, but complex organic molecules like ethyl formate, cyanopolyynes, fullerenes, amino acids, and even proteins. You can find them in meteorites, on Pluto, Mars, around newly forming stars, in reflection nebulae, in dark gas clouds in the galaxy, and even in the galactic center, among many other locations.

Here are 10 surprising places in space that all have the right raw ingredients for life. Perhaps, if the ingredients are all over, life in the Milky Way is, too.