Category: SCIENCE

Since the mid-1960s, the CMB has been identified with the Big Bang’s leftover glow. Could any alternative explanations still work?

No matter how strong the evidence is in favor a scientific theory, there will always be contrarians that come along and encourage the exploration of alternatives. This isn’t necessarily out of stubbornness, but is often done in an attempt to subject even our most well-supported theories to rigorous scrutiny and ever-stronger testing. However, oftentimes these contrarian positions have to ignore a substantial amount of evidence in order for their preferred alternatives to survive. As cosmologist Mike Turner once famously put it, “you can only invoke the tooth fairy once,” meaning that you might be able to justify a scenario with one major modification, but once you have to start doing multiple cartwheels to get around a mountain of evidence, your alternative idea is a lost cause.

Undeterred by that notion, many — mostly crackpots but including a few serious scientists — have challenged the “cosmic” interpretation of the observed cosmic microwave background (CMB), going all the way back to Fred Hoyle some 60 years ago. Are we 100% confident that the CMB really qualifies as “smoking gun” evidence for the hot Big Bang…

It’s the ultimate setup for a Thanksgiving Day disaster. The physics of water and its solid, liquid, and gas phases compels us not to do it.

One of the most enduring traditions in the United States is the Thanksgiving turkey. The one-time contender for the official bird of the nation — advanced even by Benjamin Franklin over the bald eagle — has been served at homes across the nation for centuries, with an estimated 46 million turkeys consumed nationally on the fourth Thursday of every November. Most frequently, the modern American family purchases a frozen turkey, and then begins thawing it days before the actual event. While many Americans roast their turkey in the oven, a popular trend in the early 21st century has been to deep fry your turkey: a fun production that cooks a turkey very quickly (often in just 45 minutes, as opposed to four hours or more for a 15–20 pound turkey) and gives it a delicious, unique flavor.

However, many who cook turkeys as part of our annual tradition run into a dilemma: they haven’t pulled their turkey out of the freezer early enough. What should one do with a still-frozen (either completely or partially) turkey? Turkeys normally require three or more days to fully defrost in the refrigerator, so how do you salvage…

When we see pictures from Hubble or JWST, they show the Universe in a series of brilliant colors. But what do those colors really tell us?

For just a moment, I want you to close your eyes and think about the most famous, most spectacular images of the Universe that you’ve ever seen. Did you picture planets or moons within our Solar System? Perhaps you thought of nebulous regions of gas, where new stars are forming inside. Maybe a snapshot of a recently deceased star, such as a planetary nebula or a supernova remnant, is what best captured your imagination. Alternatively, maybe you thought about glittering collections of stars or even entire galaxies, or — my personal favorite — a deep-field view of the Universe, complete with galaxies of all different sizes, shapes, colors and brightnesses.

These full-color images aren’t necessarily what your limited human eyes would see, but are instead color-coded in such a way that they reveal a maximal amount of information about these objects based on the observations that were acquired. Why do scientists and visual artists make the choices that they do? That’s what Elizabeth Belshaw wants to know, writing in to ask:

“When we see stars or galaxies from Hubble and Webb, they are in…

The last naked-eye Milky Way supernova happened way back in 1604. With today’s detectors, the next one could solve the dark matter mystery.

In this Universe, few mysteries loom as large as the puzzle posed by dark matter. We know, from the gravitational effects we observe — at all times, on scales of an individual galaxy and upward, and everywhere we look — that the normal matter in our Universe, along with the laws of gravity that we know, can’t fully account for what we see. And yet, all of the evidence from dark matter comes indirectly: from astrophysical measurements that don’t add up without that one key missing ingredient. Although that one addition of dark matter solves a wide variety of problems and puzzles, all of our direct detection efforts have come up empty, yielding only null results.

There’s a reason for that: all of the direct detection methods we’ve tried rely on the specific assumption that dark matter particles couple to and interact with some type of normal matter in some way. This isn’t a bad assumption; it’s the type of interaction we can constrain and test at this moment in time. Still, there are plenty of physical circumstances that occur out there in the Universe that we simply can’t recreate in the lab just yet. If dark…

In astronomy, a star’s initial mass determines its ultimate outcome in life. Unless, that is, a stellar companion alters the deal.

When isolated stars form, their fates are pre-determined.

Stellar lifespans rely primarily on initial mass and heavy element content.

Below 7.5% of the Sun’s mass, you’re only a failed star: a brown dwarf.

Above that but below 0.4 solar masses, you’re a red dwarf.

Fully convective, its ultimate fate is a helium white dwarf.

Humans, when we consider space travel, recognize the need for gravity. Without our planet, is artificial or antigravity even possible?

For as long as we’ve been thinking about journeying to other star systems and the planets and worlds that orbit them, we’ve been compelled to consider just how to keep human beings intact during any journey that would bridge the interstellar distances. While short trips through the zero-gravity environment of space might be feasible for humans, over longer time periods, human bodies suffer from all sorts of maladies: space blindness, bone density loss, muscle atrophy, and much more. While instantaneous teleportation or faster-than-light travel, either through a wormhole or via warp drive, might be satisfactory solutions for science fiction, when it comes to reality, we need a superior plan.

What sorts of options are there, either for antigravity or for artificial gravity, if we want to make such a solution realistic and feasible? Are there any that don’t violate the laws of General Relativity themselves? That’s what Steven Fredman wants to know, asking:

“Antigravity and non-rotational artificial gravity have been a staple of science fiction for years. But if General Relativity is correct (as it certainly…

The 5th brightest star in our night sky is young, blue, and apparently devoid of massive planets. New JWST observations deepen the mystery.

There’s a great sin that scientists all too often commit: by assuming, based only on a small number of examples (possibly as few as one), that the best scientific story we can reconstruct for those examples apply to all similar systems universally. Perhaps there’s no greater example of a field where this sin has been committed than in the science of exoplanets. Up until the early 1990s, we traditionally assumed that other planetary systems would be like our own: with inner, rocky planets, an asteroid-like belt, gas giant worlds, and then a Kuiper-like belt. Today, with thousands of exoplanets under our belt, we know of a huge variety of ways that this isn’t true:

• planets can be any mass and any distance from their parent stars,
• many super-Jupiter planets, as well as many planets between the mass of Earth and Neptune, abound,
• and that some stellar systems even have different numbers of belts than our own Solar System’s two.

Additionally, all stars don’t appear to have planets; just the ones that have sufficiently abundant fractions of…

One of the 20th century’s most famous, influential, and successful physicists is lauded the world over. But Feynman is no hero to me.

The 20th century, among the many other things it brought to humanity, brought with it a series of revolutions about the Universe. Newton’s gravity was replaced with Einstein’s General Relativity: a theory that has withstood every challenge for over a century. The quantum revolution occurred, replacing a deterministic picture of reality with an indeterminate one for particles. Later on, the notion of fields was replaced with quantum ones as well, showcasing just how bizarre reality truly is. Vital figures in those developments — such as Einstein, Planck, Schrodinger, Heisenberg, Pauli, Fermi, Bohr, Feynman, Gell-Mann, Hawking, Weinberg, and many others — have become legendary, not only among physicists and physics students, but to the general public as well.

So why, then, don’t I, personally, esteem these figures as highly as so many others do? That’s what Bert Schuhmacher wants to know, and what he wants to know specifically about Richard Feynman, asking:

“Thank you for all your explanations about the cosmos. They are of high quality and contain comprehensive knowledge. I have…

Mars and Earth were sister planets in many ways, with early similar conditions. Why did Mars die? The leading explanation isn’t universal.

When we look at planet Earth, we see a blue world with a mix of oceans and continents, clear and cloudy skies, covered in photosynthetic greenery and many other signatures of life’s presence. Mars, for comparison, is a much smaller planet that’s largely taken on a rusted red color, possessing only a thin atmosphere and with no signs of liquid water on its surface: only frozen ices. While both Earth and Mars may have formed from similar raw ingredients in terms of the atoms that make up these worlds, the tales of their planetary evolution clearly diverged long ago, with Earth becoming life-friendly early on and remaining so, while Mars lost the last traces of its surface liquid water more than 3 billion years ago.

Why are these worlds so different, today?

The standard explanation is that Mars, being much smaller, radiates the heat away from its core far more efficiently than Earth does. This causes the core to cool inside Mars much more quickly than the core inside Earth, causing any magnetic dynamo generated by Mars to fade away swiftly compared to the lifetime of the planet…

Almost everyone asserts that the Big Bang was the beginning of everything, followed by inflation. Has everyone gotten the order wrong?

At the start of the 20th century, difficult as it is to believe, we knew almost nothing about the Universe. Sure, we knew about nearby, bright stars, as well as fainter, more distant ones and an ever-growing number of nebulae in the night sky. But all of the stars we knew of were within our Milky Way, and many assumed that all of the nebulae were as well. The Milky Way itself was only known to be a few thousand light-years in size, and whether the spiral and elliptical nebulae we saw were within our own galaxy or not was not yet decided. Ideas like General Relativity, the expanding Universe, and the Big Bang had not yet even been concocted by humanity.

Discovering the suite of evidence that would lead us to those revelations, including measuring the distances to extragalactic objects, discovering the redshift-distance relation, and finding the “smoking gun” evidence in support of the Big Bang — the cosmic microwave background — were among the greatest scientific achievements of the 20th century. But today, the Big Bang is no longer seen as the beginning it once was, and many scientists…