It’s likely the universe extends forever in space and will go on forever in time. Our results are consistent with an infinite universe.
The Death of the Universe
Renée Hlozek gives us a story of dark skies, dark matter, and the dark heat death of the universe for TED-Ed.
Don’t be sad, there’s some beautiful cosmological symmetry at play in the beginning and end of everything. Plus, it’s not happening until, like, a really long time from now.
We’ll be long gone before any of that happens, right? This lesson goes along quite nicely with this week’s It’s Okay To Be Smart video, where I talk about the expiration date for life on Earth, and how we might hope to extend it through the search for extraterrestrial intelligence and habitable exoplanets.
Also don’t miss one of my favorite Wikipedia pages: The timeline of the far future.
Lots of questions about the various dimensions of motion that we experience on Earth, based on my post featuring these cute animations. Let me see if I can tackle them all together … hold on to your hats!
Does our motion through the universe (maxing out at 800 km/s or so) determine how we experience time? In short, no. Theoretically, you’d experience the same “time” whether or not we were moving through the universe, or around the Milky Way, or around the sun. “Time”, as we think of it in the cosmological sense, is inherent to the universe, it’s the state of now being different from then, and thanks to entropy, always moving in one direction.
Time, as we have defined it, is a set of hashmarks we assign to the motions and vibrations of the universe to make it easier to mark how far past “then” we are when we say “now”. Take the second. It simply describes how long it takes a cesium-133 atom to wiggle 9,192,631,770 times. It’s just much easier to say “800 km/s” rather than “800 km/9,192,631,770 cesium-wiggles”. And since we can assume that cesium-133 atoms (and sheep) wiggle the same way everywhere in the universe…
… time, in the sense of something that just exists, is universal.
How you experience time is probably a much more local phenomenon. We don’t really experience the passing of seconds, for instance, not in the big scheme of things. But thanks to our particular orbital radius around a particular star on a particular rocky planet that itself rotates at a particular velocity, we do experience something called a “day”, which would be pretty meaningless to anything that didn’t evolve on Earth (although Earth’s “day” has changed over time, and will continue to change), whether they were from another galaxy or just the next planet over.
But as confused as those aliens would be by our “day”, they would probably be totally comfortable with the “second”, because of the aforementioned shared cesium-wiggles. You have biological processes tuned to it, too, called “circadian rhythms”. So “time” is a universal phenomenon, but our experience of it is a very terrestrial thing.
So if aliens came to Earth from a planet that rotated at a different velocity, would they feel uncomfortable? No, probably not. At least not because of the rotation thing. The fact that they were on an alien planet might throw them for a loop, though.
Do you feel yourself rushing through space as Earth rotates? I don’t. Say you’re reading this on the equator. For every second that you scan this page you travel half a kilometer (that velocity decreases the closer you get to the poles, because spheres). It helps that the atmosphere is also moving along with us, otherwise that would be a helluva breeze to overcome.
Gravity is what’s primarily responsible for how you “feel” on this planet, in a non-emotional sense, and that is what would most affect any alien visitors, in a non-emotional sense. And gravity, as we all remember from every science class ever, is an attractive force that is relative to the masses of objects interacting at a particular distance. How strong, or weak, gravity was on their home planet would depend on how massive their planet was, and they would have evolved along with that gravity, no matter if it was lighter or heavier (I happen to think evolution would be a universal trait of living systems, so there).
Maybe they’d have metal bones, because their planet had supergravity. Or maybe their home planet had less gravity, and they’d be made of gel, and they’d look like this:
Incidentally, how fast a planet spins around its axis doesn’t depend on its mass, or size. It’s the result of a very random set of banging and collision events along the formation of that planet from dust to big round thing.
However, if someone somehow instantly stopped Earth, you’d feel that. Just as you broke the sound barrier.
So what’s up with that Cosmic Microwave Background velocity? Not only is Earth rotating around its axis, and orbiting the sun, and the solar system around the galaxy, and the galaxy around the local cluster … but our galaxy is moving with respect to the Big Bang itself. Since the universe has no edge, I can understand if that’s a bit hard to wrap your head around.
The CMB is a bunch of radiation that’s been radiating since ~380,000 years after the Big Bang, when atoms began to form and stuff could actually start to fly through this new thing called “space” without banging into plasma clouds. It’s been chugging along in straight lines since then, and as the universe expands those waves have been streeeeeeeeetched out into the microwave range. like pulling on the ends of a rubber band.
Because the universe has no center, that CMB radiation should look essentially the same in every direction. Except that it doesn’t. If we look in one direction, it’s redshifted (meaning we are moving away from that direction). And in the opposite direction it is blueshifted (meaning we are moving towards that direction). You know, like the Doppler effect and how ambulance sirens sound weird as they pass?
Anyway, the shift looks like this when applied to the CMB:
Something in the sky in the direction of that blue bulge is sucking us in at a few hundred kilometers per second. This is very hard to measure, considering all the other movement that’s going on, but it’s happening. Current theories suggest it could be a set of supermassive galaxies pulling on our galaxy, but we haven’t been able to observe them. So basically we don’t know. If that last part makes your head spin, head over to Starts With A Bang and read Ethan’s excellent explainer.
So, how far have you moved since you started reading this?
Noise, in analog video and television, is a random dot pattern of static displayed when no transmission signal is obtained by the antenna receiver of television set and other display devices. The random pattern superimposed on the picture, visible as a random flicker of “dots” or “snow”, is the result of electronic noise and radiated electromagnetic noise accidentally picked up by the antenna. This effect is most commonly seen with analog TV sets or blank VHS tapes.
There are many sources of electromagnetic noise which cause the characteristic display patterns of static. Atmospheric sources of noise are the most ubiquitous, and include electromagnetic signals prompted by cosmic microwave background radiation, or more localized radio wave noise from nearby electronic devices.
Microwaves are a low-energy form of radiation but higher in energy than radio waves. The cosmic microwave background blankets the universe and is responsible for a sizeable amount of static on your television set—well, before the days of cable. Turn your television to an “in between” channel, and part of the static you’ll see is the afterglow of the big bang.
How much longer until this story about static and the Big Bang makes no sense? Because I don’t know about your television, but mine hasn’t seen static in years.
What will we teach our kids then? First the dial tone, then the static of the cosmic microwave background … is nothing sacred, science?!
So what IS the Cosmic Microwave Background, anyway?
A few hundred thousand years after the Big Bang, things cooled down enough (to about 2,700 ˚C) that neutral matter like hydrogen and helium began to condense from a sea of charged protons and electrons. This released photons that have been propagating through space since that very moment.
Of course, we know that the universe is expanding, right? Those photons are expanding along with it. We are detecting them at a distance in light years almost equal to the age of the universe itself, as they have been stretched and cooled to just above absolute zero (a few degrees Kelvin).
Why “microwave”? The photon wavelengths have expanded so much during the expansion of the universe that they now sit in the microwave range, like extending a Slinky into a single, straight wire!
Check out this cool feature from Space.com to find out even more about the CMB, including how pigeon poop helped us figure out it even existed.
Planck-in’ on Billions and Billions
I’m amazed that in 2013, we can still be smacked upside the head and reminded of how little we know about our universe. Even the most basic things about it. Like, how old it is.
The European Space Agency’s Planck space telescope has collected 15.5 months worth of data on the Cosmic Microwave Background, or CMB (What’s that? Click here), and today they released the most detailed map ever of those oldest remnants of the Big Bang. It says that our universe is almost perfect. Almost.
The highlights from this new map include the finding that the universe is almost certainly 13.81 billion years old, about 100 million years older than previous estimates. And we got better estimates for the stuffness of stuff: 4.9 percent normal matter, 26.8 percent dark matter, and 68.3 percent dark energy. The universe is expanding, which is the whole reason that the CMB even exists, but this new map says it’s expanding slower than we thought.
The coolest part, though? The “almost perfect” part. The radiation that became the CMB was just sort of randomly splattered out, like we’d expect (and the randomness of the dots on the map above show that). But those little fluctuations aren’t the same everywhere! The universe appears to be slightly lopsided, and even rather cold in one part. The ESA folks say we may need “new physics” to explain why. Nice to know you cosmologists of the future will have something to work on :)
Of course, all of this just goes for the observable universe. The rest, whatever it may be (or not be), has NO EDGE. Just like Hank Green reminds us. Phil Plait has tons more dirty details behind the Planck news at Bad Astronomy.
Happy Birthday to Stephen Hawking!
The celebrated physicist is 71 years old today. One of our era’s most brilliant minds, he has contributed both to cosmological science as well as to the public’s understanding of the natural world. All this despite being diagnosed with Lou Gehrig’s disease 50 years ago, a diagnosis that usually means one has years to live, not decades. He is an example of both the strength of the human spirit and the power of the human mind.
Oh, and it’s also Elvis Presley’s birthday or something.
Illustrations by Moonrunner
Moonrunner is primarily known for its science-based illustrations, especially in such fields as astro-physics, cosmology, dark energy, black holes, the solar system and such stellar phenomena as quasars, star nurseries and pulsars. We have worked with Stephen Hawking, as well as with the scientist/authors of the National Geographic and Scientific American magazines, and also those publishing with Dorling Kindersley, Weidenfeld & Nicolson and Weldon Owen.
Click on the images to see what they represent.
That’s what I call some serious astro-illustration. Be sure to click on the photos above to check out the explanations in the slide show.
If you had in this chair some of the people who developed quantum mechanics back in the 1920s or 1930s, and you said to them, 'What is this stuff gonna DO for us?' they’d say 'Probably not much, we're trying to understand molecules and atoms, very far from everyday life.'
But the fact that you have a cell phone, the fact that you have a personal computer, the fact that there’s wondrous medical technology that’s saving lives around the world today all relies on the integrated circuit, which comes from quantum mechanics.
Quantum mechanics are responsible for something like 35% of the Gross National Product. Which is just to say fundamental research at a given moment in time can have big implications when you allow it to mature.
Cosmologist Brian Greene, in an interview with The Daily Beast.
Investing in basic science must be disconnected from traditional returns, and instead viewed as an investment in the intellectual capital of tomorrow. It’s hard to put a price tag on inspiration, and Goldman Sachs has yet to write an algorithm to predict the science of the future.
Check out his Newsweek cover story “Welcome to the Multiverse" including the rest of the interview.
Illustrated here is a geologic map of Venus’s northern hemisphere, based off radar data from the Venera 15 and 16 orbiters, Pioneer Venus orbiter, and Earth-based radar telescopes. The colors indicate various features on the surface, such as plains in yellow and light green; mountains in purple, green and blue; and volcanoes in light red and pink. (View More Planetary Maps at the Telegraph)
If you can handle the temperatures hot enough to melt lead and the caustic acid atmosphere, Venus really does look like a nice place to visit and sightsee.