PBS NOVA: Origins

Program Series

ORIGINS is a PBS NOVA four-part special featuring new findings on how Earth, life and the universe began. Who would have predicted that a hot spot left over from the Big Bang would eventually lead to the Earth, the cosmos — and to us?

Hosting the series is astrophysicist Neil deGrasse Tyson, director of the Hayden Planetarium at the American Museum of Natural History and one of the world's most popular lecturers on astronomy.

He was online Wednesday, Sept. 29, at 11 a.m. ET to take your questions on the program.

"ORIGINS" airs on PBS Tuesday, Sept. 28 and Wednesday, Sept. 29, at 8 p.m. ET. (Check local listings).

Tyson was appointed as the Frederick P. Rose Director of the Hayden Planetarium in 1996. He is the author of numerous books, including "The Sky is Not the Limit: Adventures of an Urban Astrophysicist" and "ORIGINS: Fourteen Billion Years of Cosmic Evolution," coauthored with Donald Goldsmith. He is also widely known for his regular column, "Universe," in Natural History magazine.

Editor's Note: Washingtonpost.com moderators retain editorial control over Live Online discussions and choose the most relevant questions for guests and hosts; guests and hosts can decline to answer questions.

_____________

Neil deGrasse Tyson: Thank you all for joining today's Washington Post Chat on cosmic origins. I assume that most of you have seen last night's PBS-NOVA Program on this subject. I am happy to field questions as fast I can type. -Neil deGrasse Tyson

_______________________

New York NY: Is the speed of light different when moving through different densities?

Neil deGrasse Tyson: Indeed, the famed speed of light is only constant in a vacuum. Through any other transparent medium the speed is LESS than the advertised speed of light. The denser the medium the slower is the speed. Light travels less than 40% of its speed in a vacuum when moving through a diamond, for example.

_______________________

Miami, Fla.: Neil,

Could the last "Big Bang" have been the 2nd, 3rd or 1,000,000th "Big Bang"? Is history just repeating itself?

Thanks,

Paul

Neil deGrasse Tyson: Before we had sufficient data to confirm that the universe is on a one-way trip of expansion, there was much attention given to a "cyclic" universe, were we one day re-collapse and start it over again, and again. While this idea had theoretical and philosophical adherents, at some point you have to let the data do all the talking. And the data tell us that we are on a one-way street.

_______________________

Douglasville, Georgia: Good Morning,

I watched a portion of this marvelous show
last night. Will you cover cosmic strings
in this presentation? Thank you. Asha
Tredeaux

Neil deGrasse Tyson: Thanks. Be sure to watch tonight too. But no, we do not address cosmic strings, which was the subject of NOVA's miniseries last year, hosted by String Theory expert Brian Greene. Becasue of this, we did not feeel compelled to give the subject extensive treatment.

Strong theory can influence origins stories, but, as far as we can tell, "only" when it comes to the question of what was around BEFORE the big bang.

_______________________

Franklin, Massachusetts: I was amazed by the theory that life could have been brought to the Earth by meteors!; Where did the amino acids that the meteors carried come from?

Neil deGrasse Tyson: Excellent question. Idea that life may have come special delivery from space has a name: PANSPERMIA.

The amino acids, resident on comets and asteroids, would have made themseves from the elemental building blocks of life - common ingredients in the cosmos. Carbon, one of these ingredients, is chemically fertile. have you ever wondered why filters are made of charcoal? Carbon bonds and links and adheres to practically everything -- alll by itself. There is no better element on which base an entire chemistry of life.

_______________________

Boston, Massachusetts: Some scientists believe that Earth's oceans may have been created by comets made up of dust and ice. How does ice form in space, where there is no oxygen?

Neil deGrasse Tyson: The water molecule is abundant in the universe. When Hydrogen and Oxygen are near eachother, at the right temperature, they will bond to form H2O. And by the way, H is the most abundant element in the Universe and oxygen is THIRD on the list. So there is, indeed, plenty of Oxygen in space. To make the water molecule however, requires the stuff to get concentrated (a subject of tonight's episodes). But gravity does a great job of this.

_______________________

Lamar, Colo.: Why is your program taking the approach of passing off guesswork as science? For example, many scientists today pass Miller's design of atmosphere off as totally inaccurate which invalidates the experiment.

Neil deGrasse Tyson: From what we know today, Miller's made the wrong assumption about the chemical ingredients of Earth's early atmosphere. But the takeaway lesson from his amino acid lab experiment is not that he got it wrong (which he did), but that amino acids formed all by themselves given enough time, energy and the right ingredients.

Amino acids are complex molecules and nobody had made them before in an unguided experiment.

Today, variations on his experiment, using a more accurate model of early earth, continue to manufacture amino acids. And so Miller gets the credit for starting investigators on that path.

_______________________

Baltimore, Md.: Regarding the of intelligent life in the universe, isn't it highly unlikely that any two civilizations will ever communicate given two limitations:

1. the tremendous distances involved, assuming that you can't travel faster than the speed of light

2. the billions of years of the age of the universe compared with the relatively short time in which civilizations will be born, flourish, and die

#2 makes it highly unlikely that two civilizations would ever flourish and explore the cosmos at the same time.

Neil deGrasse Tyson: These questions are the subject of the first of the two films this evening.

in preview.. I agree.

_______________________

Lancaster, PA : Is it likely that the moon will eventually get far enough away from the earth so that it will go through the asteroid belt, get larger, and smash into Jupiter (Alan, grade 3)

Neil deGrasse Tyson: How many disaster films have you been watching?????

Inded the moon is spiralling away from us, at the reate of about one or two inches per year. As the Moon's orbit grows, our rotation rate slows, and it's orbital period increases. All this continues UNTIL...a day on earth equals a lunar month. At that point we are both in what is called a 'double tidal lock'.

Were it nor for the Sun interfering, we would stay that way forever, but the Sun will continue to try to lock us with it (something it's doing now, but its effect is swamped by that of the Moon)

During that episode the moon will actually spiral back in. So, regardless, there is no threat of us losing the Moon to evil Jupiter.

_______________________

Newport News, Va.: Dr. Tyson,

There seems to be a growing consensus among researchers that the Sun formed not in isolation, but rather in a tumultuous environment akin to what we see in star forming regions such as the Eagle Nebula. Do you feel that this is an accurate picture?

Neil deGrasse Tyson: Yes, all evidence suggests that the Sun may have had hundreds, possibly thousands of siblings when born. These kinds of star clusters, however, are not tightly bound. And over time, they "evaporate" their family members into the general population of stars in the galaxy.

Some people are looking hard to find these lost family members. They would have the IDENTICAL composition as the Sun.

_______________________

Washington, D.C.: Hi, Neil,
You are amazing, and I'm very much looking forward to seeing your series "Origins." My question is: Even if all of these organic molecules were floating around in the cosmic "soup" that was the early earth, how could it be that something as complex as DNA could form naturally and replicating life could begin, even over eons of time?

Neil deGrasse Tyson: An eon is a loooooong time. Given the chemical fertilty of carbon, The DNA molecule, as remarkable as it is, does not look so far-fetched.

And carbon, on which it is based, can make more kinds of molcules that all other kinds of molecules combined.

Keep in mind, also, that there is a lot of redundant information in the molecule. So all carbon has to do is come up with the basic form.

_______________________

Lancaster, Pa.: What is the average rate of meteor falls to earth today? --Gretchen (5th grade)

Neil deGrasse Tyson: Earth plows through several hundred tons of meters per day.

Some are visible as the burning trail of a "shooting star".

Others actually make it to the ground. But must of the "ground" is ocean, and most of Earth's land mass is uninhabited.

So recovereing these meteors-turned-meteorites is always a challenge.

_______________________

Lancaster, Pa.: If the moon gets far enough away, will there be no tides? (Gretchen 5th grade)

Neil deGrasse Tyson: When the Moon and Earth reach a double tidal lock (see a previous answer), all Lunar tides will cease, but there will still be a small solar-based tide. But nothing as fun as that caused by the Moon.

_______________________

Potomac, Maryland: Totally Fascinating

You cover the events that lead carbon atoms to bond with hydrogen and nitrogen to form amino acids and eventually DNA. From there you leap to the creation of reptiles and mammals. Will you address the evolution of single cell life to complex life forms.

Neil deGrasse Tyson: In episode three -- the first episode tonite -- we talk about the emergence of intelligence, but we do not dwell on, for example, the Cambrian explosion of life, where the first interesting features of life appeared, like sight, locomotion, limbs, etc.

_______________________

Auburn, CA: Before the Big Bang, from where did the material come that exploded?
What was it made of?
If the microorganisms that started life on earth came from outer space, how did these begin?

Neil deGrasse Tyson: We do not know where the big bang came from. Although there are cogent ideas (with good theoretical foundations) that suggest our uniiverse is just one of countless many in a "multiverse".

But those ideas have not yet graduated to the realm of supportive data. Plus I do not know anyone who would be first to visit these other universes to get proof. The laws of physics will likely be slightly different from one universe to the next, making them supremely dangerous to visit.

========

Asserting that miicroorganisms stowed away on meteors that slammed into Earth of course simply shifts the question of Origins to another place. But the delivery of the raw ingredients for life does not. That stuff is everywhere.

_______________________

Staten Island, NY: In reference to the formation of water on the planet, could you please explain what is Heavy Water. How does it differ from water as most peole know it?

Neil deGrasse Tyson: Regular water is two hhydrogen atoms attached to one Oxygen atom -- written in the familar way: H2O

The identity of an element comes from the number of Protons in its nucleus. Hydrogen has one. Oxygen has eight, Carbon has six. Uranium has 92.

If you add or subtract neutrons, which life alongside the protons in the nucleus, you will get what are called "isotopes"of the element, but the identity remains linked to the proton-count.

Add an neutron to hydrogen, you get "heavy hydrogen". Sometimes called Deuterium, and given the unofficial symbod "D". So you would write heavy water as: D2O. And sometimes only one of the hydrogens is heavy. you would write that one as DHO.

_______________________

St. Peters, Mo.: It has already been established with absolute certainty that the moon did not originate from the same mass as the earth.

Neil deGrasse Tyson: The Moons Origins was unkown (though fully speculated) before the Apollo missions (1969 -- 1972)

Any with comparisons of lunar rock and Eath rock could ideas take root.

And only in the last several years has a consensus been achieved that the Moon is mostly made of Earth material, minus the iron - forcing the idea that the Moon was made from our Crust, which itself is low in iron compared with our core.

The series presents this consensus to the public for the first time.

_______________________

Saugatuck, Mich: Mr. Tyson: First of all I smiled when I saw you talking about standing on the roof of Skyview Apartments - I grew up in the Bronx (around Fordham Rd.). You used binoculars to view the moon and that led you to your present position at the Hayden Planetarium - quite an accomplishment.

My question pertains to the relationship to the magnetic North Pole and its' effects on our wather, seismic activity, etc. Does it affect us and how will it affect us in the future?

Neil deGrasse Tyson: Da Bronx was indeed where I first saw the sky. But the hayden was where I first saw the "real" sky. Born and raised in the Bronx, I am of course a Yankee fan, but I have nothing against the Red Sox, and, don't tell anybody, but i secretly long for a Red Sox / Cubs World Series.

The meandering pole, as far as we know, does not affect weather, climate, etc. But it does affect how you read your compass. If you are north of the Geomagnetic north pole, your compass will point South. You would probably want to know this fact when hiking in northern Canada.

Better yet, bring a hand-held GPS and leave the compass at home.

_______________________

Huntsville, Texas: I noticed in the computer animations on ORIGINS that asteroid belt seemed to be an incredibly densely crowded place. But I've been under the impression that thouth there are trillions of asteroids, the spacing between them is huge. What would be a typical asteroid-asteroid spacing in the belt?

Neil deGrasse Tyson: Busted!

Indeed, the total mass of the asteroid belt is less that 5% of the Moon! So there really isn't much out there. So the common SciFi scenes of space ships dodging rocks that pass through the belt is a gross exxageration, as was the cinematic license taken on those visuals used for the Origins film.

That being said, it woould look that crowded if we just happend to come upon a collision between two asteroids, itself not infrequent over the lofe of the solar system. So I left the scene in.

_______________________

Tecumseh, Mich.: Hi Neil,
Greetings from a former Austin Rowing
Club member who knew you back in the
day! I watched last night with my
five-year-old -- after 45 minutes he had to
go get his crayons and paper in order to
draw before-and-after pictures of Earth.
(The "iron catastrophe" version is on the
fridge this morning.) Here's my question,
probably a dumb one, but I still have to
ask: why is Earth (and all other planets)
more or less round? Is the shape the
result of spinning? And if so, was Earth a
different shape back when it was
spinning so fast that days were only 6
hours long?

Neil deGrasse Tyson: I still have callouses on my hands from all those years of rowing. Thanks for the remebrance.

I once wrote an essay for natural history magazine titled: "On Being Round" which was all abour round things in the cosmos.

I will put that essay on-line on my personal website this afternoon. The link will look like this:
http://research.amnh.org/users/tyson/essays/OnBeingRound.html
but give me a few hours to set it up.

Back when Earth was fast-spinning, it surely would have been bulgey at its equator. In fact it still is: Earth is wider across its equator than it is from pole to pole, but not as severe as saturn, which rotates once every ten hours. Fast-spinning Saturn is 10% wider at its mid-section than from pole to pole.

_______________________

Montreal, Qc: Hi Neil, my name is Francis.

Thank you for taking the time to answer today's questions, I loved Part 1 and 2 of Origins, looking forward episode's 3 and 4.

My question:

Was the first form of life closer to Animal or Plant, and why?

Neil deGrasse Tyson: First life underwent photosynthesis, converting our CO2 atmosphere to Oxygen. Something plants do daily. But these were cyanobacteria. So you would have to ask a biologist how they would classify these things.

But if, by animals, you mean creatures and beasts, then plants had to precede them since plants serve as the base of the food chain.

In other words, everything you will ever eat with a calorie content was derived from something that was once alive. (No escaping that one -- even vegetarians must kill that which was once alive)

_______________________

richmond, va: I watched the program yesterday. If asteroids bring water and life to earth, why is it not taking form any where else where asteroids are hit?

Neil deGrasse Tyson: It's the comets that deliver water, not the asteroids, although in the early solar system, the distinction between the two was surely blurred -- icy asteroids would have been common.

if we were hit by a comet, it would indeed add to Earth's water budget. But that wouldn't matter much becasue the impact will have left us extict.

_______________________

Lancaster, Pa.: Why does Australia have the most evidence of the earliest life on earth? --Alan (3rd grade)

Neil deGrasse Tyson: Australia is fertile ground for this sort of thing because it has long been geologically inactive and meteorologically mild, thus preserving rocks, craters, and other things that would otherwise get eroded away. Plus hardly anybody loves there, so the destructive influence of civilization is minimized.

_______________________

Austin, TX: Regarding your response about a solar sibling having the exact same composition - wouldn't it be possible for a massive star to quickly form, go SN, and pollute its nearby star-forming region of more slowly-forming, less massive solar siblings, thus giving them a bit more in the heavy element department?

Neil deGrasse Tyson: Good question. yes, pollution is possible, but the amout of pullution would be miniscule. Stars do not occupy much of the area that surrounds an exploding star, whereas gas clouds do.

_______________________

new york ny: Question on beautiful sunsets. Seems we often go long stretches without good sunsets. Do they occur more in some seasons than others, or in some geographical areas? Any way to predict when they will occur? Seems they don't happen the evening before a rainy day.

Neil deGrasse Tyson: Your question is remarkable for several reasons.

1) not many new yorkers care about sunsets -- the buildings are in the way.

2) Sunsets are at their most beautiful (colorful) when the atmosphere is contaminated by suspended particles, like smog.

3) The fact that your sunsets have been boring lately is a simple testament to the prevalence of clean air in your environment. Yes, NYC is a cleaner city than it once was.

The most reliable sunsets continue to be in the southwest, the "dust-belt" where there's always something in the air that belongs on the ground.

_______________________

Neil deGrasse Tyson: So many questions, so little time. Plus, my hands are cramping up. I must sign off now. But thank you all for your wonderful questions, and I invite you to watch parts three and four of PBS-NOVA origins, tonight.

Th companion book, can take your further when it's all over, if you are interested. "Origins: fourteen billion years of Cosmic Evolution"

p.s. The kids among you out there asked excellent questions. There is hope for us all.

Keep looking up --- signing off. -Neil deGrasse Tyson

_______________________