This Is How Astronomers Will Finally Measure The Universe’s Expansion Directly

“This is why, by measuring the redshifts and distances to a slew of objects ⁠— objects at a variety of different distances and redshifts ⁠— we can reconstruct the expansion of the Universe over its history. The fact that a whole slew of disparate data sets are all consistent with not only one another but with an expanding, evenly filled Universe in the context of relativity, that gives us the confidence we have in our model of the Universe.

But, just as we didn’t necessarily accept gravitational waves before they were directly measured by LIGO, there’s still the possibility that we’ve made a mistake somewhere in inferring the properties of the Universe. If we could take a distant object, measure its redshift and distance, and then come back at a later time to see how its redshift and distance had changed, we’d be able to directly (instead of indirectly) measure the expanding Universe for the first time.”

We’ve measured the distance to literally billions of objects all over the Universe, from within our galaxy to more than 30 billion light-years away. By observing how the light from these distant objects is shifted, we’re able to infer that the Universe is expanding. We’re able to infer how that expansion rate has changed over time. And we’re able to infer what the Universe is made of: a monumental accomplishment.

But what we’ve never been able to do, as of 2019, is to watch an individual, distant galaxy physically expand away from us in real-time. With the new generation of 30-meter class telescopes we have coming online, though, all of that is poised to change. When the ELT arrives, the largest of the next generation telescopes at 39 meters, it will have the capability to make this measurement directly by observing the same sets of quasars 10 years apart.

You’re going to get to learn a new term today: redshift drift. When we measure it, we’ll have our first direct observation of the Universe as it physically expands on human timescales.

8 Fast Facts You Must Know About Mercury’s Last Transit Until 2032

7.) NASA’s Kepler discovered zero Mercury-like planets around Sun-like stars. Transiting Mercury imperceptibly dims the Sun, reducing its brightness by merely 0.0027%.”

From 12:35 to 18:04 Universal Time on November 11, 2019, Mercury will, from the perspective of Earth, appear to transit across the face of the Sun. Even though Mercury is only a little more than 3,000 miles in diameter, the fact that it passes between us and the Sun means that it will appear 1/194th as large. If you want to see the silhouette of Mercury against the brilliant backdrop of the Sun, you’ll need either a clever image projection setup or a telescope (with 50-100x magnification, ideally) with an appropriate solar filter.

But whether you view it for yourself or not, there’s an amazing set of science facts everyone can learn to appreciate this momentous event. Come get them today in a mere 200 words, tops!

Ask Ethan: Did We Just Find The Universe’s Missing Black Holes?

“As interesting as this new black hole is, and it really is most likely a black hole, it cannot tell us whether there’s a mass gap, a mass dip, or a straightforward distribution of masses arising from supernova events. About 50% of all the stars ever discovered exist as part of a multi-star system, with approximately 15% in bound systems containing 3-to-6 stars. Since the multi-star systems we see often have stellar masses similar to one another, there’s nothing ruling out that this newfound black hole didn’t have its origin from a long-ago kilonova event of its own.

So the object itself? It’s almost certainly a black hole, and it very likely has a mass that puts it squarely in a range where at most one other black hole is known to exist. But is the mass gap a real gap, or just a range where our data is deficient? That will take more data, more systems, and more black holes (and neutron stars) of all masses before we can give a meaningful answer.”

Last week, an incredible new story came out: scientists discovered a massive object some 10,000 light-years away that emits no light of its own. From the giant star in orbit around it, we were able to infer its mass to a well-constrained range, with the mean value hovering right at 3.3 solar masses.The lack of X-rays from it, based on the field strength associated with neutron stars and the orbit of the giant star itself, very strongly indicates that this object is not a neutron star, but a black hole.

Does this mean we’ve discovered a black hole in the so-called “mass gap” range? Yes! But does it disprove the existence of a mass gap overall? Not so much. Come get the full story on this edition of Ask Ethan!

Even In A Quantum Universe, Space And Time Might Be Continuous, Not Discrete

“In General Relativity, matter and energy tell space how to curve, while curved space tells matter and energy how to move. But in General Relativity, space and time are continuous and non-quantized. All the other forces are known to be quantum in nature, and require a quantum description to match reality. We assume and suspect that gravitation is fundamentally quantum, too, but we aren’t sure. Furthermore, if gravity is ultimately quantum, we don’t know whether space and time remain continuous, or whether they become fundamentally discrete.

Quantum doesn’t necessarily mean that every property breaks down into an indivisible chunk. In conventional quantum field theory, spacetime is the stage upon which the various quanta act out the play of the Universe. At the core of it all should be a quantum theory of gravity. Until we can determine whether space and time are discrete, continuous, or unavoidably blurred, we cannot know our Universe’s nature at a fundamental level.”

If you could look at the Universe down to the smallest possible scales, fundamentally, what would you find? Would you discover that space and time really could be broken up into tiny, indivisible entities where the was a length scale and a timescale that could be divided no further? Would you discover that space and time were quantum in nature, but were instead a continuous fabric? Or would you discover something else, like that space and time weren’t quantum or that there was a fundamental “blurring” that prevented you from seeing below a specific scale?

Quantum, surprisingly to many, doesn’t necessarily mean it can be broken up into indivisible chunks. Space and time might not be discrete even if they’re quantum. Time to learn the difference.

New Video On Quantum Supremacy!

In October 2019, a team of researchers used a 53-qubit quantum computer to solve a complicated problem in just three minutes (and change) that they alleged would take a normal, “classical” computer some 10,000 years to solve. With speed-ups like that, it’s no stretch to say that a concept known as Quantum Supremacy has been achieved.

But is that truly what happened? The problem that they solved efficiently with a quantum computer isn’t useful in any way; it was specifically chosen precisely because it’s a problem that is extremely difficult and computationally intensive to solve for a classical computer, while being computationally “easy” for a quantum computer. Moreover, IBM disputed the 10,000 year figure, claiming that their Summit supercomputer, a powerful classical computer with some 250 Petabytes (!!) of storage, could solve that problem in under 3 days.

Has Quantum Supremacy actually been achieved? Find out in this new, bonus video that Dr. Laura Manenti (a recent podcast guest) and I created together!

This Is How Distant Galaxies Recede Away From Us At Faster-Than-Light Speeds

“All the galaxies in the Universe beyond a certain distance appear to recede from us at speeds faster than light. Even if we emitted a photon today, at the speed of light, it will never reach any galaxies beyond that specific distance. It means any events that occur today in those galaxies will not ever be observable by us. However, it’s not because the galaxies themselves move faster than light, but rather because the fabric of space itself is expanding.

In the 7 minutes it took you to read this article, the Universe has expanded sufficiently so that another 15,000,000 stars have crossed that critical distance threshold, becoming forever unreachable. They only appear to move faster than light if we insist on a purely special relativistic explanation of redshift, a foolish path to take in an era where general relativity is well-confirmed. But it leads to an even more uncomfortable conclusion: of the 2 trillion galaxies contained within our observable Universe, only 3% of them are presently reachable, even at the speed of light.

If we care to explore the maximum amount of Universe possible, we cannot afford to delay. With each passing moment, another chance for encountering intelligent life forever slips beyond our grasp.”

If you look at a galaxy, chances are you’ll see that it appears to be receding away from us, as its light is redshifted. The more distant you look, the greater the redshift, and hence, the faster the implied recession speed. But this interpretation runs into problems very quickly: by the time you’re looking at galaxies more than 13-to-15 billion light-years away, they start to appear as though they’re receding faster than the speed of light!

Impossible, you say? Sure, if you only consider special relativity. If you insist on general relativity, it all falls into place. Here’s how.

What Really Put The ‘Bang’ In The Big Bang?

So what is it that put the “bang” in the hot Big Bang? It’s the end of inflation. There is a state prior to the start of the hot Big Bang that set it up and provided it with the initial conditions of being spatially flat, the same energy density everywhere, always below a certain threshold temperature, and uniform with quantum fluctuations superimposed atop it on all scales.

When this inflationary state ended, the process of cosmic reheating transformed that energy — which had previously been inherent to the fabric of space itself — into particles, antiparticles and radiation. That transition is what put the “bang” in the hot Big Bang, and led to the birth of the observable Universe as we know it. The details of this were first worked out in the 1980s, back when inflation was just a theoretical idea, and have been confirmed by observations taken in the 1990s, 2000s, and 2010s. For decades, scientists have known what put the “bang” in the Big Bang. At last, now the general public can share in that knowledge, too.

Last week, a story came out that claimed to discover what put the “bang” in the Big Bang. Only, the actual study talked about what occurs in a conflagration or an explosion, which is completely unrelated to anything that occurs in the earliest moments of the hot, dense state that kicked off our Universe as we know it. Fortunately, we don’t have to wonder about what put the “bang” in the Big Bang; this is something scientists have known for decades.

The answer? It’s the cosmic reheating that occurs at the end of inflation that gives rise to the first moments of the hot Big Bang. Come get the real, hype-free story today.

This Is Why Dark Energy Is The Biggest Unsolved Problem In The Universe

“The true fact of the matter is that, observationally, dark energy is behaving as though it’s a form of energy inherent to the fabric of space itself. WFIRST, NASA’s flagship astrophysics mission of the 2020s (after James Webb), should allow us to reduce the measured constraints on w down to the 1-or-2% level. If it still looks indistinguishable from a cosmological constant (with w = -1) then, we’ll have no choice but to reckon with the quantum vacuum itself.

Why does empty space have the properties that it does? Why is the zero-point energy of the fabric of the Universe a positive, non-zero value? And why does dark energy have the behavior we observe it to have, rather than any other?

There are an infinite number of models we can cook up to describe what we see, but the simplest model — of a non-zero cosmological constant — requires no additions or modifications to match the data. Until we make progress on understanding the quantum vacuum itself, dark energy will remain the biggest unsolved puzzle in all of modern theoretical physics.”

Since 1998, astronomers have known that the Universe isn’t just expanding, but that the more distant a galaxy gets from us, the faster it appears to recede away from us. The reason for this isn’t because of motion, but rather because there’s more than just matter and radiation in the Universe; there’s also a form of energy that appears to be inherent to space itself: dark energy.

While it may be theoretically fashionable to concoct new fields, modifications to gravity, or other forms of new physics, it’s unnecessary. What we really need to do is understand the quantum vacuum, and we don’t. Here’s the story so far.

This One Distant, Red, Gas-Free Galaxy Defies Astronomers’ Expectations

“When two similarly-sized galaxies merge, it triggers a starburst: a massive formation of new stars. Under the right circumstances, some gas will form stars while the remainder is expelled, lost forever to the intergalactic medium. Once the gas for forming new stars is used up, the galaxy simply ages as the bluest, most massive stars die off. Over billions of years, only the redder, dimmer, lower mass stars remain.”

In astronomy, young galaxies actively form stars, and glow bright blue through the process. Only after many billions of years and at least one cataclysmic event do galaxies settle down into a gas-free, red state, once all the bluer stars have died out. “Red and dead” galaxies appear in the late Universe, normally as giant elliptical galaxies that lost their gas aeons ago.

Which is why this one galaxy is so puzzling: it’s red, dead, massive and compact, but it’s also sending us its light from 10.8 billion years ago!

How did this galaxy get so old-looking when it’s actually so young? The mystery continues, but here’s what we know so far.

The Science Of Why 5G Is (Almost) Certainly Safe For Humans

“Finally, the benefits that 5G will bring to society in the coming decade are truly revolutionary. In addition to the accelerated speeds that regular consumers will see, laying the infrastructure for 5G will enable civilization-changing smart technologies and a virtually unlimited number of device connections. 5G will enable blossoming technologies that rely on connectivity to the internet to go widespread, from connected self-driving cars to smart plugs, lights, cameras, toothbrushes, thermostats, healthcare monitoring devices and more. The Internet of Things is coming, and 5G is the technology that will take it mainstream.

There are lots of real hazards out there in the world, but 5G — much like vaccines, fluoridated drinking water, and the vapor trails left by airplanes — aren’t among them. In the search for truth, society should rely on the full suite of scientific evidence, rather than fear or ideology, to guide us. When we do, all of us can reap the benefits of a safe, connected world.”

Remember how big of a leap it was when we transitioned from 3G to 4G technologies? The jump from text and SMS messaging to streaming online video represented a factor of ~500 improvement in bandwidth, and the jump to 5G should not only give us an additional factor of 100, but should enable billions of additional connected devices. The Internet of Things is coming, and 5G is the technology that will bring it to fruition.

But is it safe for humans? Although there’s a lot of fearmongering and conspiracy theorizing surrounding it, there’s an awful lot of science, too. Here’s why it indicates that 5G is almost certainly safe for humans.