Category: universe

Ask Ethan: Can We Really Get A Universe From N…

Ask Ethan: Can We Really Get A Universe From Nothing?

“One concept bothers me. Perhaps you can help. I see it in used many places, but never really explained. “A universe from Nothing” and the concept of negative gravity. As I learned my Newtonian physics, you could put the zero point of the gravitational potential anywhere, only differences mattered. However Newtonian physics never deals with situations where matter is created… Can you help solidify this for me, preferably on [a] conceptual level, maybe with a little calculation detail?” 

You’ve very likely heard two counterintuitive things about the Universe before. One of them is that the Universe arose from nothing, and this defies our intuition about how it’s impossible to get something from nothing. The second is that we have four fundamental forces in the Universe: gravity, electromagnetism, and the strong and weak nuclear forces. So how, then, do we account for the fact that the Universe’s expansion is accelerating? Isn’t this clearly evidence for a fifth force, one with negative gravity?

Guess what? These two counterintuitive aspects of reality are related. If you understand them both, you’re one step closer to making sense of the Universe.

Did Time Have A Beginning?

Did Time Have A Beginning?

“Even though we can trace our cosmic history all the way back to the earliest stages of the hot Big Bang, that isn’t enough to answer the question of how (or if) time began. Going even earlier, to the end-stages of cosmic inflation, we can learn how the Big Bang was set up and began, but we have no observable information about what occurred prior to that. The final fraction-of-a-second of inflation is where our knowledge ends.

Thousands of years after we laid out the three major possibilities for how time began — as having always existed, as having begun a finite duration ago in the past, or as being a cyclical entity — we are no closer to a definitive answer. Whether time is finite, infinite, or cyclical is not a question that we have enough information within our observable Universe to answer. Unless we figure out a new way to gain information about this deep, existential question, the answer may forever be beyond the limits of what is knowable.”

If you didn’t know anything about the Universe, you might intuit three possibilities for how time originated. Either it had a beginning a finite duration ago, or it existed for an eternity into the past, or it is cyclical in nature, with no beginning, end, or true delineation between past and future. But we have lots of physical evidence today. We know about the Big Bang and what its limits are. We know about cosmic inflation, which preceded and set up the Big Bang. And we know about dark energy, which determines the fate of our Universe.

With everything we know, what can we say about whether time had a beginning or not? Not enough, unfortunately, but the possibilities remain tantalizing. Find out what we do and don’t know today!

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Wow 😂 (by @perryfellow on instagram)

Could Parallel Universes Be Physically Real?

Could Parallel Universes Be Physically Real?

“Inflation may give us an enormously huge number of Universes that reside within a greater multiverse, but there simply aren’t enough of them to create an alternate, parallel you. The number of possible outcomes simply increases too fast for even an inflationary Universe to contain them all.

In all the multiverse, there is likely only one you. You must make this Universe count, as there is no alternate version of you. Take the dream job. Stand up for yourself. Navigate through the difficulties with no regrets, and go all-out every day of your life. There is no other Universe where this version of you exists, and no future awaiting you other than the one you live into reality. Make it count.”

Our observable Universe, as vast and enormous as it may be, is still finite. There are a finite number of galaxies containing a finite number of atoms and particles that have existed for a finite amount of time since the Big Bang. There’s an idea in quantum physics call the many-worlds interpretation, where all the various quantum outcomes that are possible actually do occur, but they simply occur in parallel Universes: where the Universe was identical to our own until a critical moment when a particular quantum decision occurred.

Does the existence of a multiverse mean there’s a Universe out there where you also exist, but made different decisions? The answer is probably no. Here’s why.

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When Did The Universe Become Transparent To Li…

When Did The Universe Become Transparent To Light?

“The Universe became transparent to the light left over from the Big Bang when it was roughly 380,000 years old, and remained transparent to long-wavelength light thereafter. But it was only when the Universe reached about half a billion years of age that it became fully transparent to starlight, with some locations experiencing transparency earlier and others experiencing it later.

To probe beyond these limits requires a telescope that goes to longer and longer wavelengths. With any luck, the James Webb Space Telescope will finally open our eyes to the Universe as it was during this in-between era, where it’s transparent to the Big Bang’s glow but not to starlight. When it opens its eyes on the Universe, we may finally learn just how the Universe grew up during these poorly-understood dark ages.”

There are two ways that astrophysicists talk about the Universe becoming transparent. The first is when the particles from the Big Bang finally form neutral atoms, becoming “transparent” to the leftover photons from that era. The second is hundreds of millions of years later, when those same neutral atoms are reionized, and starlight can travel freely through intergalactic space. Which one is right? When did the Universe become transparent to light? 

The truth is we need them both, as they make the Universe transparent to different types of light. Come get the full story today.

Scientists Didn’t Really Find The First …

Scientists Didn’t Really Find The First Molecule In The Universe

“All of the early Universe’s helium should have been destroyed when hydrogen became neutral, as helium hydride is far less energetically favorable than the formation of neutral hydrogen. Once you cool below a certain critical threshold, your helium hydride will interact with neutral hydrogen, preferentially forming hydrogen molecules (H2) and isolated helium atoms (He). The Universe’s first molecule didn’t last long; by the time perhaps 500,000 years passed, it was all gone.

But later on, even in the modern Universe, there’s a perfect candidate location where helium hydride should exist in our Universe today: in the ionized plasmas of dying Sun-like stars. With temperatures high enough to ionize hydrogen, but plenty of neutral helium expelled from the dying stars outer layers, these planetary nebulae should be ideal homes for helium hydride.”

We found the first molecule in the Universe! Well, not quite. Helium hydride, formed between neutral helium atoms and ionized hydrogen nulcei, is an ion that gets created at specific temperatures, when hydrogen is ionized but helium is not. We created it in the laboratory way back in 1925, and astrophysicists theorized that it would be created in two places: in ionized plasmas around dying Sun-like stars, and in the very early Universe, when it was still too hot to form neutral hydrogen atoms. In big, interesting news, we’ve finally discovered helium hydride in space, finding it using the SOFIA telescope and observing the planetary nebula NGC 7027. It’s a remarkable story all on its own merits.

But this isn’t the same as the helium hydride formed in the aftermath of the Big Bang. That was all destroyed long ago, and none of it remains to be seen today.

Scientists Didn’t Really Find The First …

Scientists Didn’t Really Find The First Molecule In The Universe

“All of the early Universe’s helium should have been destroyed when hydrogen became neutral, as helium hydride is far less energetically favorable than the formation of neutral hydrogen. Once you cool below a certain critical threshold, your helium hydride will interact with neutral hydrogen, preferentially forming hydrogen molecules (H2) and isolated helium atoms (He). The Universe’s first molecule didn’t last long; by the time perhaps 500,000 years passed, it was all gone.

But later on, even in the modern Universe, there’s a perfect candidate location where helium hydride should exist in our Universe today: in the ionized plasmas of dying Sun-like stars. With temperatures high enough to ionize hydrogen, but plenty of neutral helium expelled from the dying stars outer layers, these planetary nebulae should be ideal homes for helium hydride.”

We found the first molecule in the Universe! Well, not quite. Helium hydride, formed between neutral helium atoms and ionized hydrogen nulcei, is an ion that gets created at specific temperatures, when hydrogen is ionized but helium is not. We created it in the laboratory way back in 1925, and astrophysicists theorized that it would be created in two places: in ionized plasmas around dying Sun-like stars, and in the very early Universe, when it was still too hot to form neutral hydrogen atoms. In big, interesting news, we’ve finally discovered helium hydride in space, finding it using the SOFIA telescope and observing the planetary nebula NGC 7027. It’s a remarkable story all on its own merits.

But this isn’t the same as the helium hydride formed in the aftermath of the Big Bang. That was all destroyed long ago, and none of it remains to be seen today.

How Can We Still See The Disappearing Universe…

How Can We Still See The Disappearing Universe?

“In fact, we can even think about what you’d see if you were to look at a galaxy whose light hasn’t arrived at our eyes yet. The most distant object we can see, 13.8 billion years after the Big Bang, is presently 46 billion light-years away from us. But any object that’s presently within 61 billion light-years of us will someday have that light eventually reach us.

That light was already emitted, and is already on its way to us. In fact, that light is already most of the way there; it’s closer than the 15 billion light-year limit of what we could possibly reach if we left for it at the speed of light. Even though the Universe is expanding, and even though the expansion is accelerating, that journeying light will someday arrive at our eyes, giving us, in the far future, the ability to see even more galaxies than we can today.”

Dark energy seems to present a paradox. On the one hand, galaxies are receding from us as the Universe expands, meaning we can never reach them once they’re beyond a certain point, and that the light being emitted by them can also no longer reach us. But even though these galaxies are a part of our dark energy-dominated Universe, we’ll always be able to see them in the future once they become visible to us.

If the Universe is disappearing, how can we still see the galaxies in it? Come get the answer to one of cosmology’s biggest (misconception-related) puzzles today!

This Is Why The Multiverse Must Exist “This p…

This Is Why The Multiverse Must Exist

“This picture, of huge Universes, far bigger than the meager part that’s observable to us, constantly being created across this exponentially inflating space, is what the Multiverse is all about. It’s not a new, testable scientific prediction, but rather a theoretical consequence that’s unavoidable, based on the laws of physics as they’re understood today. Whether the laws of physics are identical to our own in those other Universes is unknown.

If you have an inflationary Universe that’s governed by quantum physics, a Multiverse is unavoidable. As always, we are collecting as much new, compelling evidence as we can on a continuous basis to better understand the entire cosmos. It may turn out that inflation is wrong, that quantum physics is wrong, or that applying these rules the way we do has some fundamental flaw. But so far, everything adds up. Unless we’ve got something wrong, the Multiverse is inevitable, and the Universe we inhabit is just a minuscule part of it.”

Skeptical about the Multiverse? You’re not alone. After all, how can you be confident that something must exist if the experimental, measurable, or observational evidence that’s required to validate its existence isn’t located within our observable Universe? It’s a reasonable thought, but there are ways to know something that go beyond verifying the exact phenomenon we’re looking for. This is why theoretical physics is so powerful: it not only allows you to draw conclusions about things you have not yet observed, but about things you cannot observe at all.

Come find out how, and learn why the Multiverse really must exist.