---

     In the intermediate section of the newsletter, we have included some questions asked by fifth and sixth grade students from Hoover School about the nature of time and matter, and about vacuums. These questions are considerably more difficult than other questions we have received from this age group. We are very impressed by these students want to share their questions with your students, although we realize that many of them will find the questions challenging (we did!).

     We have also included a questionnaire about the Network in this issue. We would appreciate your help in evaluating our work. If you have any comments or suggestions not covered by the questionnaire, please feel free to add them to it. We are looking forward to hearing from you. -- Judy Hill & Jack Easley

Q1. How many stars are there?
A1. There are about 2,000 stars we can see on a clear night without a telescope if we get away from the city lights. If we went to the opposite side of the Earth, we could see another 2,000. Our galaxy may have 100,000,000,000 stars, but we can't see through the dust and gases to get a good estimate. We assume that many other galaxies are like ours, and there are millions of galaxies, but most are too far away to see individual stars even in a good telescope. Next year a super telescope is scheduled to be launched by the space shuttle into orbit around the earth where it can see further than the telescopes on earth see. It will be operated by robot computers and send down TV pictures.

Q2. How big is Pluto?
A2. Pluto's radius is estimated at 1,200 km. The earth's radius is 6,378 km.

Q3. Is Pluto cold?
A3. Yes. It is 5,900,000,000 km from the sun, 40 times further away from the sun than the earth is. If you care to know how cold, it is about 50-60 degrees Celsius above absolute zero, while our temperature averages over 300 degrees Celsius above absolute zero. Pluto is thus a lot colder than dry ice, which "smokes" at about 200 degrees Celsius above absolute zero.

Q5. Does Pluto have trees?
A5. No way. It's too far from the Sun.

Q6. What kind of materials is the universe made of? (Arian)
A6. Everything we find on the Earth is made out of elements like hydrogen, helium, lithium, and 89 other elements. However, plasma in fluorescent or neon lights, and some computer screens like PLATO, has electrons and other parts of atoms flying around. The Sun and the stars are plasma, with many smaller parts of atoms moving around loose in them. Besides atoms and parts of atoms, there are panicles of light, x-rays, radio waves, gravity, and other things that wouldn't weigh anything if you could stop them and put them on a scale. The standard theory holds that the universe began with only electrons, positrons (just like electrons except positively charged), photons (of light and other kinds of radiation), and some protons, neutrons, and gravitons (particles of gravity), and that atoms of various kinds were formed later out of protons, neutrons, and electrons. -- JE

Sample from the second batch of questions:

Q8. What is a dwarf star?

Q2. Does anybody or anything live on Pluto?

Q9. How big is the universe?

Q4. How many comets are there?

Q5. Where does the planets come from?

Q10. Is the universe a color? (any color)

Q11. What is a falling star?

Q6. How many falling stars is there?

Q7. Is there any pollution in space?

Q13. How do the planets get their colors?

The following questions were answered by the students who asked them:

Q1. Can we live on the moon?
A1. Yes

Q2. Is Pluto cold?
A2. Yes.

Q3. How big is Pluto's moons?
A3. VERY big! !!

Abell, George O. (1984). Realm of the Universe, Third Edition. Philadelphia, Saunders College Publishing.

Payne-Gaposchkin, Celia (1952). Starsin the Making. Cambridge, Mass., Harvard University Press.

Kaufmann, III, William J. (1979). Planets and Moons. San Francisco, W. H. Freeman and Company.

Morrison, David, & Owen, Tobias (1988). The Planetary System, Reading, Mass., Addison-Wesley Publishing Co.

Weinberg, Steven (1977). The First Three Minutes: A Modern View of the Origin of the Universe. New York, Basic Books, Inc.

Wyatt, Stanley P. (1964). Principles of
 Astronomy. Boston, Allyn and Bacon, Inc.

     Four years later I graduated from college and went to work at that same laboratory of the Carnegie Institution of Washington, on a war-time job studying the ionosphere and I saw the old and the new atom smashers there. They were very impressive to me, a young radio engineer. World War II ended in 1945 with the result of the scientists' research and development, called the Manhattan Project, namely an atom bomb dropped both on Hiroshima and Nagasaki, Japan, with tremendous loss of life, following a test bomb explosion in Neyada.

     In fact, the Manhattan Project developed so rapidly, that a controlled fission, atomic pile had worked in December, 1943, the month I started to work for Carnegie. That pile was built under the direction of Enrico Fermi, underneath the University of Chicago stadium, but I didn't hear about that until much later, That pile of uranium and graphite was the first controlled nuclear reactor, with the graphite to slow down the neutrons and prevent explosion as a bomb. However, the smaller atoms that resulted from splitting the very heavy Uranium 235 (or the even heavier Plutonium 239), are radioactive themselves and difficult to dispose of. Before I left Carnegie's ionospheric project, I monitored the ionosphere in Hawaii during the explosion of the first hydrogen bomb, a bomb that released even more energy by instantaneous fusion of hydrogen atoms on Bikini Atoll in the Marshall Islands. When my job was ended in August, 1946, I went to the University of California in Berkeley to study physics. There I heard lectures by J. Robert Oppenheimer who had spearheaded the fission bomb research and by Hans Bethe, who explained how the sun operates by atomic fusion of four hydrogen atoms into one helium atom -- which means that there is no danger for a long, long time that it will burn out. For transformations between these two lightest of the elements, energy is released by fusion rather than by fission, as with the heaviest atoms.

     By having been involved, if only peripherally, in the monitoring the fusion bomb, I became interested in research on controlled fusion, because there were no radioactive products of the reaction itself, just lots of neutrons. However, I soon became aware of the devastation of fusion bombs, and their lingering radioactive effects in the Eniwetok environment and population. Changing my career from scientist-engineer to teacher, I took my first full-time teaching job in the Marshall Islands right after I had seen the Eniwetok explosion light up the ionosphere in Hawaii. I met Marshallese students whose families had been displaced from their home environment on Bikini and become dependent on government hand outs, and I found out that many Marshallese had become seriously ill from radiation sickness during the Eniwetok explosion.

     In spite of large efforts in subsequent years to control nuclear fusion by overcoming the electromagnetic repulsion of hydrogen atoms for each other, thus allowing the strong and weak nuclear forces to pull their nuclei together into a helium atom, the Tokamak and other devices built to contain high temperatures like that of the sun have failed, consuming more energy than the fusion itself produced. So, it was with great interest that I read and listened about six weeks ago to the electronic media reports about the claim by two University of Utah chemists that they have successfully created controlled nuclear fusion of deuterium (hydrogen with a neutron and a proton for a nucleus) in a glass vessel, generating four times as much energy as consumed. Physicists again seem to be skeptical about the chemists' claim, and chemists tend to be enthusiastic about them, but the efforts to replicate the experiment seem to have called forth a variety of explanations and produced a variety of results. At any rate, nothing has produced so much scientific burning of the midnight oil for some time. Phillip Morrison, an MIT astrophysicist who worked with the Elementary Science Study (ESS) in the '60s, and who with his wife, Phyllis, reviews children's science books every December for Scientific American, has said of the new claims for cold fusion, "Either it will be a wonderful solution to our needs for energy, or it will amount to nothing." Time will tell.

     Perhaps the strangest news item was the report that in 1926 two German physicists reported that they had detected the fusion of hydrogen atoms into helium atoms in a block of palladium at room temperature. 9 months later they withdrew their report, saying it was an error. Does history repeat itself? You can see why I am fascinated by this whole development in the last six weeks that has the physicists and chemists of the world in an uproar.

     Science Network News is published by the Center for Instructional Research and Curriculum Evaluation (CIRCE) in the College of Education at the University of Illinois. Judy Hill and Jack Easley are the editors. They welcome your questions and comments. Write to them at CIRCE, 270 Education Building, 1310 S. Sixth Street, Champaign, IL 61820, or at their FrEdMail (computer) addresses:
UIUCED!JHILL@UIUCED2 or
UIUCED!JEASLEY@UIUCED2.
(Your computer can call ours at 800-527-9937.)

Things I Don't Know
.........
I wake, what bird's that, what kind of
     dog moans so?
Is that a maple or an oak on Mapleton
    Street? What flowers, weeds &
    ferns, those in the backyard? What
    car goes by awhoosh? A Pontiac
    swash up the street,
A Chevy, Ford, a Pinto, a Grammarian, a
    4 wheel drive GM?
What star I saw last night when clouds
    lifted & Orion's belt
Glittered gold on blue? or was that
    amber on azure? As my eye
Followed his arrow past the North Star
    thru the void, was that a tiny galaxy shimmering?
Where's Sagittarius, which way is the
    black hole at the center of the
    Spiral Nebula?
Where's Sahel where a million
    children starve?...
.........
- Allen Ginsberg

Fusion in a Bottle                     Pons and Fleischmann claim they
                                                 made atomic nuclei fuse in a simple cell

Palladium encircled by platinum is               The deuterium atoms are squeezed
placed in "heavy" water, in which hy-         into the palladium's latticelike structure"
drogen is replaced by deuterium. Elec-        Eventually they fuse, releasing en-
tricity separate oxygen from deuteri-            ergy and. in some experiments, neu-
um, which is absorbed by palladium.          rons and a form of helium.

Dear Reader,
We realize that teaching and studying science is often difficult, and we want to be helpful in any way possible. To help us improve our service, please tell us how you think we arc doing so far, and in what ways you think we need to change. Please circle the appropriate responses below. Feel free to add comments anywhere on the questionnaire. Fold, tape, and mail it when you have completed it. Please return the questionnaire by the end of the school year.

1. Has your class made use of the science network?

 yes.     how?     asked questions           used newsletter material          other

 no.

2. Are our answers to science questions

 very helpful          somewhat helpful          a little helpful          not helpful

3. Overall, do you think your district should (please circle one)

discontinue          continue          expand          reduce

their participation in the Science Network?

4. Are you:

a teacher a supervisor a pupil other
 

5. What are the major problems in teaching science you wish someone could help you with?
 

6. It is taking us longer to answer questions than we had originally anticipated.  Are our answers coming too slowly?

If yes, why?

 easier access          more privacy          more motivation to use network          other

9. We have received questions from only a small percentage of the total classes subscribed
for the network. We are worried about this. If you are not using the network, could you
tell us frankly why you're not using the network, and how we could be of more help?
 
 

10. Would it be helpful if we visited schools more often?

11. How else could we be more helpful?

12. Is our newsletter, Science Network News,
 
very helpful          somewhat helpful          a little helpful          not helpful

13. Which features of our newsletter do you find helpful or interesting?
 
Questions and answers          Supplemental information          Student editions
 
                         Newsflashes          Jack's Journal           Other

14. Which features of our newsletter would you like to see dropped or changed?

 Questions and answers          Supplemental information          Student editions
 
                       Newsflashes          Jack's Journal           Other
 

15. Has any particular answer to a question or anything else in a specific issue of the
 newsletter been especially useful? (please specify)
 

Thank you for taking time to respond! Jack Easley and Judy Hill
 

Science Network News Questionnaire
CIRCE
270 Education Building
1310 S. Sixth Street
Champaign, IL 61821

Students in Mrs. Lindstrom and Miss Cosgrove's first grade classes asked:

Q4. Do land turtles lay their eggs in nests?
A4: All turtles, both those that live on land and those that live in the water, lay their eggs on land in "nests". But a turtle's nest is very different from a bird's nest. Sea turtles come to shore and dig a hole in the sand using their back flippers. They then lay their eggs in the hole Finally, the sea turtles kick sand over the eggs to hide them and protect them and then swim back to sea. It takes a sea ripley about four minutes to build her nest, lay her eggs, cover them over, and return to the water.

     The fresh water Musk turtles lay their eggs in nests dug in mud banks, or hide them among plants growing near the shore of a lake or river, or in the wood of dead tree stumps. Some land turtles also lay their eggs in tree stumps or under dead logs. - JH

Q5. What is the difference between the amount of eggs laid by a sea turtle and the land turtle?
A5: In general, sea turtles lay a lot more eggs than land turtles. On average, sea turtles lay about 100 eggs at a time, while land turtles lay, on average, three to six eggs at a time. Fresh water turtles lay an average of 25 eggs at a time, but fresh water turtles living in northern areas will lay a lot more eggs than the same kind of turtle living in warmer areas (75 to 80 eggs instead of 25~. Do you have any ideas about why the northern turtles lay more eggs?

There are exceptions to these averages: some sea turtles, like the diamond-back terrapin, lay as few as five eggs at a time, while others, like a hawksbill turtle in the Seychelles, may lay as many as 250 eggs at a time. - JH

The first graders had some interesting ideas about why northern turtles lay more eggs:

- because northern turtles are bigger;

- because it's colder in the north;

- because fresh water is colder in the north;

-it's harder to lay eggs where it is warmer;

- maybe northern turtle s hibernate, so when they come out they can lay more eggs.

Judy Hill: The part of science I like best is doing experiments. When I was in grade school, I had a chemistry set. I liked to make things with my chemistry set. My experiments didn't always work out as I had planned There was an experiment in the set where you could make fireworks You weren't supposed to do that experiment unless your parents were around.
One day my brother and I were playing with the chemistry set on a cardtable outside and we decided to try making fireworks by ourselves. The fireworks worked so well that we set the table and the grass around it on fire.  We were very lucky and no one was injured. It was a long time before my parents let anyone near that chemistry set again. Just a reminder - Don't Play With Fire! .

I also like my job answering science questions. I learn about a lot of interesting things. One day I was trying to find out what the differences are between sea turtle eggs and land turtle eggs. One thing I learned while reading about turtle eggs is that snapping turtles lay eggs that are about the size and shape of ping pony balls, and when they are fresh, they bounce! That doesn't exactly answer the question, but I thought it was a fun thing to learn.
Even though I like science, I didn't always like science class. Once, my class was reading our science book and it said " Some day people may be able to walk on the moon." I thought that was rather silly since I had seen Neil

Armstrong and other astronauts walking on the moon on T.V. Sometimes what we learned in science class was out of date (like the statement about the moon), or wasn't very interesting, or just didn't make sense with what I thought I already knew about the world. Then I didn't like science class.

Jack Easley: I have always liked science and technology. (Technology is making things and inventing things.) It's a lot of fun to make telephones, radios, raise plants and animals, and study the weather, the stars, and the thing s we use a lot, like water and air. Everyday, I learn something new, if I'm lucky. I think I'll go on liking to study science the rest of my life.
We asked Kristen to write and tell us if she likes science or not.
Kristen answered:  I like science, because it is interesting. I also like science because I like doing experiments. I don't like science because sometimes it is hard.

Kristen also asked Dr. Easley two more questions:
Q2. How did you learn science?
A2. I learned science mainly by trying experiments on my own. It wasn't easy, but it was fun! I remember, in second grade, I experimented with faucets and drinking fountains by putting my finger on the place where the water comes out. It made a mess, and usually I had to clean it up, so it's better if you can find a faucet outdoors or a drinking fountain in a park. I found out how the water felt under pressure, so smooth and round, pressing hard on my finger or hand. I knew where the city water tank was, and I knew that I was feeling the water pushing down from that high tank. Later, I took faucets apart to find out how they work. To do that, you have to turn the water off somewhere, and you need a pipe wrench. Usually, you take faucets apart to replace the washer on an old-fashioned faucet, if the faucet drips when it is turned off. I also used to take alarm clocks apart and try to put them together again. Once I succeeded.

In fourth grade, my teacher had a huge terrarium in the hall outside our classroom. I used to play with turtles, frogs, and salamanders she had in it. I liked that a lot better than being in the classroom. I guess she liked science a lot too. Most grown-ups don't seem to like science very much, so it can be hard to learn science. How do you learn science?

Q3. How did you get to be a teacher?
A3. I used to teach my younger sisters about science things. When I was about 12 years old, I learned how to play a cornet and figured out how the valves work to change the length of the tube. I taught some other children how to play trombone, clarinet, and drums, so I could have a band. The trombone and clarinet both change notes like the cornet, by changing the length of the tube.
When I went to summer camp, I got to teach boy scouts about birds and plants. When I went to college, I got to teach college students about math and physics. I got a job teaching math to the football team, because everyone in that college had to take math. Also, I got to teach in the physics lab, to explain how to do the experiments. Later, I took courses on how to teach, but mostly, when I saw that my students weren't learning well, I figured out new ways to teach by studying how I learned.

If you want to learn science and be a good teacher, you have to be able to do things for yourself that no one has shown you how to do. I once read a good book called Totto - chan, by a Japanese woman named Kuroyanagi. It tells how, when she was in elementary school, she did many things herself that no one showed her how to do. -- JE
 

WHAT'S HAPPENING?

 

Simple Science Experiments
These science experiments are from the book by
Hy Ruchlis called Bathtub Physics (Harcourt,
Brace ~ World, 1967).

"Floating" a paper clip on water

 

Bend a clip to make a holder, as shown. Place a small paper clip on it, as shown. (gently lower the clip flat onto the water in the bathtub or bowl. If you do this carefully, the paper clip will stay on top of the water as the holder goes below the surface.
Now try it at a slight tilt. This time the metal clip plunges to the bottom, as you expected it to. Something held Up the first clip, but what?

Take a plastic tumbler or other container and push it completely under water in the bathtub Wait until it fills with water. Then turn it upside down. Slowly pull the tumbler up. Surprise! The water rises with the tumbler until it is much higher than the water in the tub!

"Lifting" water out of the bathtub

There seems to be nothing holding up the water. But something must be, or it would fall. What can the force be?

 Students in Mrs. Jones' fifth grade class at Bottenfield School in Champaign are studying the solar system and galaxies. They asked the following questions:

Q1. How do the planets get their colors?
A1: The color of the earth comes from the blue water of the ocean, the whiteness of clouds and snow and ice, the brown rocks of dry land, and the green of forests is turned blue by the atmosphere. Mars is mostly dry rocks. The iron ore in these rocks makes Mars appear red. Venus is always covered with clouds, unlike the earth, and the clouds give it the color we see. The other planets get their colors in similar ways. -- JE

Q2. What is a falling star?
A2: A falling star is a meteor, a little piece of rock or even a speck of dust that burns up in the earth atmosphere as it enters the atmosphere at a high speed. -- JE

This question was asked by Danny Ginsburg, a student in Mrs. Zito's combined 5th and 6th grade class at Hoover School:

Q1. Does time exist without matter?
A1: Taken literally, I would answer your question no. Within our experience, both time and matter exist. If what you really mean is "Could time exist without matter?" or "Which came first, time or matter?", your question is much more interesting (and more difficult to answer). These questions lead into a very active area of scientific and mathematical research.

     These are, in fact, questions that philosophers, astronomers and physicists have been considering for centuries. The answers formulated depended on what the questioner believed about time, matter, and the origin of the universe. These attitudes, in turn were (and are) influenced by religious beliefs and other assumptions. The way societies answer these questions can have a significant impact on their approach to the care of the environment. Instead of a single answer to your question, what follows is a review of the ways a variety of people have approached this question. I hope that you will respond to this with your theories and further questions about time and matter.

     In the Hindu view of reality, time is a never-ending cycle of four ages: the "Krita" or perfect age, the "Treta" or 3/4 age (during which everything is only 3/4 as good as it was in the perfect age), the "Dvapara" or 1/2 age (during which everything is only 1/2 as good as it was in the perfect age), and the "Kali" or bad age. Hindu philosophers say we have been in the bad age since 3102 BC, and that we have about 427,000 years more to go in this age. According to this theory, after each of the four ages have passed 1000 times, the universe is destroyed. There is no matter then until the universe is remade. So under this system the answer to your question would be yes, time sometimes exists without matter.

     Aristotle (born in 384 BC), was an ancient Greek philosopher who is sometimes called "the father of science." He (like many other ancient Greek philosophers) believed that matter and time have both always existed, and will always continue to exist. I suspect that Aristotle would have answered your question with the ancient Greek equivalent of: "No, since time and matter have always and will always both exist, time cannot exist without matter. "

     The ancient Hebrew creation stories, which are the basis of much of the Jewish, Christian and Muslim traditions, hold that the universe was created at some time in the past. This would mean that the existence of matter has a beginning point; or in other words, that matter didn't always exist. I'm not sure that these stories put any limit on the beginning of time, but some philosophers of these traditions do. In the fifth century AD, the Christian theologian St. Augustine set the date for the beginning of the universe at 5000 BC. Augustine believed that "time was a property of the universe that God created, and that time did not exist before the beginning of the universe." (Stephen Hawking, A Brief History of Time, 1988). In other words, Augustine would vote no.

     In contrast, Immanuel Kant (in Critique of Pure Reason, written in 1781) stated that time is the most basic concept, because everything that happens takes place in time (including the first occurrence of matter). Kant believed that it was impossible to know as a fact whether the world (and therefore matter) had a beginning point or not, but he assumed that even if matter hadn't always existed, time had. So Kant would probably respond to your question that time may have existed before matter, but since we don't know whether or not matter always existed, we don't know if time did in fact exist before matter.

     In 1915, Albert Einstein proposed the general theory of relativity. One aspect of this theory is that time is "relative", that is, that time is related to space, and that the speed at which time passes depends on where you are and how fast you are moving. (If you would like more information about this theory, or some examples of how this aspect of it has been tested, please ask.) You might be wondering how Einstein's theory of relativity is relevant to your question. First, two physicists (Stephen Hawking and Roger Penrose) have shown that this theory implies that the universe must have a beginning, and may have an end. So if you believe this theory, you believe that matter hasn't always existed. Additionally, relativity has changed the way people look at time. Before Einstein developed this theory, westerners (by westerners I mean mostly Europeans and people of European descent) believed space and time were "absolute" or unchanging. In other words, things happen in situations limited by space and time, but space and time were assumed to be unchanged by these events. The general theory of relativity says that space and time are changed by events in the universe, and so it is meaningless to talk about the existence of space and time outside the existence of the universe. In other words, Einstein would have said no, time doesn't exist apart from matter.
 
     The question of the beginning of t universe was brought more clearly in scientific analysis in 1929 when Edwin Hubble observed that the universe was expanding. He proposed that there was a time about 10 or 20 million years ago when a "big bang" occurred and everything in the universe was created. According to this theory, at the "big bang" all matter was located at one point, and the galaxies have been forming and moving away from that point ever since (thus causing the universe to expand). Many scientists consider this "big bang" to be the beginning of time, as well as the beginning of the universe (because, as Hawking explains in A Brief History of Time, any events which may have occurred prior to this time can be ignored as they have no influence on events after the "big bang". Additionally, if you accept Einstein's general theory of relativity, time would have no meaning prior to this beginning of the universe).

      Using a theory called "the quantum theory of gravity," Stephen Hawking has proposed a new idea about time and the universe. He describes the universe as a "space-time" surface" which has no boundaries.(If youwant more details on this, let me know.) It is interesting that this same physicist who showed that Einstein's general theory of relativity requires the universe to have had a beginning is now trying to show that the universe has no beginning or end such as the "big bang". If Hawking is correct, then time is just one more dimension of the physical world and it could not exist without matter. Much of Hawking's book, A Brief History of Time, explains how Hawking came to hold this view and how it fits with other scientific theories. --JH

     Related information: Stephen Hawking, according to the cover of his book, "is widely regarded as the most brilliant theoretical physicist since Einstein." He is a Professor of Mathematics at Cambridge University. Hawking has ALS (amyotrophic lateral sclerosis - sometimes called Lou Gehrig's disease). This has resulted in his being confined to a wheelchair. He is also unable to speak, but he communicates through his computer and a voice synthesizer. He was diagnosed with ALS in the mid-1960's, and told that he had only a year or two to live. Since that time he has completed his Ph.D. and is a very productive theoretical physicist.

References
Beardsley, Monroe, ed. (1960). The European
 Philosophers from Descartes to
 Nietzsche. Random House: New York
 (1960). (for information about Kant)
Durant, Will (1962). The Story of Philosophy..Time: New York. (for information about Aristotle)

Hawking, Stephen (1988). A Brief History of Time. Bantam Books: New York. (For more information about most of the topics covered in this answer)

Tiebout, Harry (1966). Comparative Religion. Stipes Publishing Co.: Champaign. (For more information about the Hindu view of the universe - it is interesting that Professor Tiebout, like Professor Hawking, also had ALS)

Katherine Chan, also a student in Mrs. Zito's class at Hoover School asked:

Q1. Is it true that nothing exists in a vacuum?

Q2: Is there a dark place that is really empty?
A.1&2: I think that the best answer, today, to both of these questions is "no." Let me explain:
Although a vacuum has been defined as a place with nothing in it for more than 2,000 years, in the last 70 years that definition has been changing among the physicists and astronomers who study space. The reason is that in 1919 an astronomer found evidence that gravity not only attracts things that have weight when they sit on a scale, like you or me, or the things we can touch or pick up, but gravity also attracts light, heat radio waves, and other things we can't pick up or put on a scale. Eddington found, as Einstein had predicted, that during an eclipse of the sun when stars were visible, that light from some stars was bent when it went by the sun. So some scientists now think that light exists in the vacuum of outer space.

     We have a lot of vacuums bottled up in glass tubes - like cathode ray tubes in TV’s and computer monitors, like light bulbs, and thermos bottles, and we could keep these tubes in a dark container and keep out all the light. We could also insulate them from heat and shield them from radio waves. But we can't shield them from gravity. Some scientists say that gravity is something that goes everywhere, even in a vacuum. Some even say there are gravity particles, called gravitons, going from on object to another.

     My answer to the first question might also be the answer to Q2. But it may not be the answer you want. That is why I think your question is so interesting: I'm not sure if the two questions are really the same or different.

     Have you heard of "black holes"? In spite of their name, I don't think of them as empty. Whether or not they exist at all is another question. Einstein predicted them, and some things have been found that look like black holes, but more research is needed. There might be one in the center of our galaxy, but there is too much dust in the way for astronomers to see it.

    It would have been easier to answer your questions a hundred years ago.  The answer then would have simply been "no." Many people today would still say "no." Science is like that - even some science teachers give one answer in one course and a different answer in a another course. Can you guess why that is? Please write again and tell me what I missed, or what else you want to know. -- JE

Katherine Chan also commented that her question was related to Danny Ginsburg's question about time and matter. Judy Hill addressed this comment as follows.

     I'm not sure about how these questions are related. Is the connection that, in your question, you were asking if time exists without matter in a vacuum? If you were, I still think the answer would be "no" because vacuums aren't really empty. Energy, in the form of gravity (and sometimes also as light and radio waves) exists in vacuums. Jack Easley wrote more about this in his response to your question (but if you want more information about this, please ask). Einstein showed that energy and mass, or matter, are interchangeable. So you can't really say that vacuums are empty (or without matter).

     There is at least one other way your question is related to the question about time and matter. I was listening to "Stardate", an astronomy program from the University of Texas at Austin, on Urbana's public radio station a few days ago. They were explaining how, in black holes, space becomes like time - it moves in only one direction instead of moving freely in any direction.

     Time, as far as we know, moves only in one direction (forward). In a black hole, matter moves only in one direction (in). Nothing that falls into a black hole can ever get out. Stephen Hawking talks about black holes a lot in his book A Brief History of Time. On page 89 of that book he says, "Anything or anyone who falls through the event horizon [into a black hole] will soon reach the region of infinite density and the end of time." * Perhaps it is possible in black holes for matter to exist without time.

* In order to say this, Hawking had to make several assumptions: 1. that black holes exist; 2. that Einstein's theory of general relativity (see the answer to Danny Ginsburg's question) holds; 3. that a black hole is sort of the end of time for a star; and 4. that conditions inside a black hole are like what they would have been at the "big bang" - if you believe that occurred This is getting more complicated then I had intended it to. As always, if you want any of this explained in more detail, write back -- JH

Can You Identify These Galaxies?