--------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2Q00003 Date: 02/20/98 From: ARNOLD G. GILL Time: 02:51pm \/To: MIKE ROSS (Read 4 times) Subj: S of L. Hello MIKE! On 19 Feb 98, MIKE ROSS wrote to Arnold G. Gill: MR> I've always heard that if the universe had been created differently MR> then its physical constants would be different from what they MR> presently are. This implies that the current properties of space are a MR> direct consequence of the progenitor events which unfolded at the BB. MR> In other words the very laws of physics could have had many different MR> outcomes. I can't find a reference now so I'll be getting back to you MR> on this. I agree with you on this. However, it is also true that changing the value of the physical constants will cause a universe to arise in which life as we know it is not possible. Now we have introduced the anthropic principle - the universe is the way it is because if it were any different, we would not be here to see it and ask that question. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2Q00004 Date: 02/20/98 From: ARNOLD G. GILL Time: 02:53pm \/To: MIKE ROSS (Read 4 times) Subj: S of L. Hello MIKE! On 19 Feb 98, MIKE ROSS wrote to Arnold G. Gill: AGG>> I would have to dispute this. On small scales, there is no AGG>> discernible Hubble expansion, since the local fundamental forces AGG>> will cause the matter to "slide" over the spacetime. MR> I'm pretty sure there's a contradiction here. How can there be two MR> kinds of space at the same time? Isn't space the same everywhere? Matter exists on the fabric of spacetime (imagine balls on a tightly stretched rubber sheet). If the fabric is stretched, the balls could move with it (if the stretching is done very quickly), but are just as likely to _slide_ over the stretching fabric due to inertia and attractive forces (especially for a slow stretch). So, the stretching is only experienced by objects far from us, not anything nearby. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2Q00005 Date: 02/20/98 From: ARNOLD G. GILL Time: 02:57pm \/To: MIKE ROSS (Read 4 times) Subj: Gravity and Black Holes Hello MIKE! On 19 Feb 98, MIKE ROSS wrote to Arnold G. Gill: AGG>> The quantum FTL that everyone is crowing about is _not_ AGG>> information, in the sense that it is impossible to determine AGG>> what the information is except by comparison. For example, a AGG>> set of experiments on the one photon will give a set of random AGG>> results, as predicted by probability theory. Another set of AGG>> experiments carried on at the same time on the other photon also AGG>> gives a set of random results as predicted by their respective AGG>> probabilities. It is only when the two experimenters get AGG>> together and compare results is it apparent that the experiment AGG>> on the first photon affected the results of the experiment on AGG>> the second photon in an FTL manner. But no real information is AGG>> transmitted. MR> Here's an excerpt from a news report: MR> "the Rome scheme encodes one of the entangled photons with a specific MR> polarization state and transmits this state to the other entangled MR> photon. Although different from the Innsbruck experiment (which had a MR> 25% teleportation success rate) and the original theoretical proposal MR> for teleportation, this scheme works 100% of the time if the receiver MR> applies the right transformations on the second photon. (D. Boschi et MR> al., upcoming article in Physical Review Letters)." MR> I see the words "transmits" and "specific". As far as I can understand MR> this stands for real information. I also read "100% of the time" and MR> not random. You must remember that this is a news report. As for the story, "works 100% of the time _IF_ the receiver applies the right transforms". How does the receiver know what the correct transforms are? Well, the agree on what will be done beforehand. So much for real information being transferred. If I send a message in a bit stream by applying a succession of transforms, the reciever doesn't which transforms I applied and in what sequence. So all that is received is a random stream of bits - with zero information. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2Q00006 Date: 02/20/98 From: ARNOLD G. GILL Time: 03:00pm \/To: MIKE ROSS (Read 4 times) Subj: S of L. Hello MIKE! On 20 Feb 98, MIKE ROSS wrote to Sid Lee: MR> It is not only high gravitational situations which exhibit curvature. MR> Distant galaxies exhibit redshifts because of spacetime curvature not MR> simply by the line of sight recession one might assume. MR> When we look at distant objects we are looking back to a time when the MR> universe was smaller. Thus we can in this sense indirectly measure MR> curvature. Just as your balloon people could draw a series of circles MR> and discover that the value for pi is not the same for very large MR> radii. I doubt this will work. The most distant objects have a redshift of about 5. The redshift of the recombination era was around 1000, the redshift of the Big Bang is by definition infinite. Lets say the universe was 1 meter across at recombination. It is now about 1000 times larger. There is very little difference in the curvature of a sphere of radius 1000 meters and one of 995 meters. What is being measured is the deceleration of galaxies with large redshifts. The evidence is still inconclusive - distances are not known well enough to give meaningful results. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2Q00007 Date: 02/20/98 From: BARTON PAUL LEVENSON Time: 02:39pm \/To: MIKE ROSS (Read 4 times) Subj: Re: Big Bang BPL> No. Not even in Gamow's old "cosmeg" model was it an explosion in BPL> space. MR> Yes, he did. MR> Gamow proposed that many of the heavy elements currently found in the MR> universe were synthesized by "thermonuclear reactions" which took place MR> while the universe was very young. MR> To me the intended meaning is clearly BANG! Sorry, you're dead wrong. Big Bang nucleosynthesis took place early after the Big Bang, yes, but it was not the Big Bang itself. There was no preexisting space the Big Bang expanded within. The Big Bang was an explosion OF space, not an explosion of an object IN space. MR> Consider this, why anyone bothered to use the word BANG to describe the MR> primordial creation event if it wasn't meant to be taken literally and MR> then to further add the qualifiers BIG and HOT as in HOT BIG BANG? The term was coined by Steady-Staters. MR> I feel it is plainly mistaken to suggest it was not an explosion; a MR> matter explosion which expanded into a space which was either already MR> there or forming and unfolding just a few scant moments ahead of it. What you feel is irrelevant. What matters is what the theory actually says. --- Maximus 3.01 * Origin: SoundingBoard, Pittsburgh PA (1:129/26) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2Q00008 Date: 02/20/98 From: BARTON PAUL LEVENSON Time: 02:42pm \/To: BILL GODFREY (Read 4 times) Subj: Hubble's constant. BG> A quicky question for all you bods out there. BG> I've just been told that Hubble's constant has been BG> recently calculated as 42. BG> My question, 42 what? BG> (There I go, talking just like those maths teachers who 42 kilometers per second per Megaparsec distance. Recently proposed values cluster around 67. The lowest I've seen in recent years is 30, the highest; 78. I have a table of estimates going back to 1917 if you're interested. --- Maximus 3.01 * Origin: SoundingBoard, Pittsburgh PA (1:129/26) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2Q00009 Date: 02/19/98 From: JOHN PAZMINO Time: 05:17pm \/To: BILL GODFREY (Read 4 times) Subj: Hubble's constant. BG> I've just been told that Hubble's constant has been recently calculated as 42. BG> My question, 42 what? BG> (There I go, talking just like those maths teachers who sarcily say "12 BG> elephants" when people don't write down the units.) BG> Unless it's a ratio. Peculiar constat: its value keeps changing! The '42' means '42 km/Mpc.s'. That is the spatial outwelling due to Hubble expansion increases 42Kn/s per million parsecs. If you be cunning you see that this unit is [ditance]/[distance.time], which reduces to 1/[time]. Inother words the Hubble factor (we no longer like 'constant') is an inverse time. Its reciprocal is the actual time, some 18ish billion years, the expansion has been going on since the bigbang. The assumption is that this expansion was the same over all this time. We believe by the models of cosmology that the expansion was much faster in the biginning and has been gradually slowing up to the present era. So the Hubble time, 1/(Hubble factor), is the maximum age of the universe; it is somewhat younget than that due to the slowing or deceleration of the expansion. 42Km/Mpc.s is rathr a low value for Hubble factor. But it will give an larger timespan for the universe and would alleviate the 'age' problem. This is the seeming conflict between the ages of the oldest stars, by stellar evolution, and the age of the universe, by Hubble expanion. --- RoseReader 2.52 P005004 * Origin: MoonDog BBS Brooklyn,NY 718 692-2498 (1:278/230) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2R00000 Date: 02/21/98 From: KEITH AUCLAIR Time: 10:57am \/To: JOHN PAZMINO (Read 4 times) Subj: Ngc 2244 JP> It's the equivalent of a 4-1/2 magnitude star. It is at the threshold JP> visibility from the outer boros of New York on the darker nights. From JP> Manhattan it's just beyond range (transp is normally 4.0). From a JP> darksky site it's obvious but only as a dimmer star. Hi John, That's without optical aid, correct? Ok...thanx for clearing it up for me. :) ... Taglines are irrelevant. You will be assimilated into the Blue Wave. ___ Blue Wave/QWK v2.20 [NR] --- PCBoard (R) v15.22/2 * Origin: Akasha's Bubble Bath & Magic Potion (1:163/403) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2R00001 Date: 02/20/98 From: PETER WEST Time: 07:24pm \/To: BILL GODFREY (Read 4 times) Subj: Hubble's constant. In a message of <14.02.98>, Bill Godfrey (2:2500/702.25@FidoNet) writes: BG> I've just been told that Hubble's constant has been recently BG> calculated as 42. BG> BG> My question, 42 what? You obviously haven't read/recalled /The Hitchhikers Guide to the Galaxy/: 42 is the answer to 'Life, the universe and everything'. :-) Regards /Peter/ -- C:\ Bad command or file name! Go stand in the corner. --- JetMail 0.99beta22 * Origin: Pete's Point at the #Fortress BBS# :~) (FidoNet 2:254/105.13) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F2R00002 Date: 02/21/98 From: MARK KAYE Time: 09:39am \/To: ALL (Read 4 times) Subj: Skyline for 1998-02-20 Sky and Telescope's SKYLINE for 1998 After traveling through space for more than two decades, the Voyager 1 spacecraft is now the most distant human made object. At about 06:10 UT on February 17th, Voyager 1 surpassed the distance of long time record holder Pioneer 10. Since being launched in 1977, Voyager has journeyed 10.4 billion kilometres from the Sun. It is racing out of the solar system at 17.4 km per second. Despite its age and distance, the spacecraft is still functioning and sending back data. Researchers expect that it will reach the heliopause, the boundary of solar influence and officially enter interstellar space in three to five years. As Project Manager Ed B. Massey points out, by the time Voyager's 20 watt signal reaches Earth, it is "so faint that the amount of power reaching our antennas is 20 billion times smaller than the power of a digital watch battery." The spacecraft should have enough electrical power to operate for another 20 years. At that point, the spacecraft will be more than 20 billion km away. On Thursday, February 26th, the Moon will not only be new, but positioned in a direct line between the Sun and Earth and thus eclipsing the Sun. The lunar shadow will sweep across the Earth in just a few hours. The eclipse will be total in parts of northern South America and the Caribbean, where over the next several days, thousands of eclipse chasers will gather to witness one of nature's greatest spectacles. If you can not be there for totality, you have a couple of options. Observers in much of the United States and eastern Canada can view the partially eclipsed Sun. Visibility is south and east of a line from Southern California through Kansas, Michigan, Quebec and Labrador. See the map and other information in the February "S&T" page 82 (it is also on SKY Online at http://www.skypub.com/eclipses/eclipses.html). Another option is to watch the eclipse online, more than a dozen individuals and organizations are gearing up to broadcast the event over the Internet. You can catch the action at SKY Online (http://www.skypub.com/eclipses/s980226c.html) where we will post (or link to) live or nearly live images of the eclipse from throughout the Americas, including views from the Caribbean transmitted from one or more of the five "S&T"/Scientific Expeditions tour groups. There is more to the eclipse activities than people gazing upward and snapping a few souvenir photographs. NASA has outlined what some of its scientists will doing. Researchers from NASA's Goddard Space Flight Centre will study the magnetic activity of the solar corona and there will be simultaneous observations made using the Solar and Heliospheric Observatory (SOHO) and Ulysses spacecraft. With the eclipse week Moon out of the way, the situation is somewhat improved for viewing Comet 55P/Tempel-Tuttle, which is also slipping closer to the horizon. The comet, the parent of the Leonid meteor stream, continues to move south through Pisces, seemingly making a beeline toward Saturn. Observers report it is 8th magnitude and about four arcminutes in diameter. Here are positions for Tempel- Tuttle at zero hours UT in 2000.0 co-ordinates: R.A. Dec. February 21 01:14 12.2 23 01:14 11.3 25 01:14 10.5 That is all for this week. MK --- Maximus 2.02 * Origin: http://www3.sympatico.ca/mark.kaye/ (1:249/109.1)