February's ending, and Spring is not far off. I've done some new sign designs at my local Starbucks. Snowdrops, sunshine, and luminous cupcakes here:

and here's a lavish art nouveau display for the Chocolate Marble Macchiato. Both are done in acrylic markers on heavy coated boards.

Wonderful Cosmology

I just finished reading a classic book by British cosmologist Martin Rees, titled BEFORE THE BEGINNING. Much of the rambling about black holes in my previous few entries has been inspired by this book, which takes you on a tour of the incredible cosmological discoveries of the last century. He illuminates not only black holes, but grand galactic structures, quasars, supernovae, active galaxies emitting intense radiation, neutron stars, and dark matter. His writing is clear and unpretentious, though at times it got a bit too technical for me to follow. The only thing wrong with this book is that it was written in 1997, before the astonishing discovery, in 1999, that the universe is expanding faster, rather than slowing down. Rees speculates about this, but it had not been confirmed when this book was written. That discovery puts a few chapters of his out of date. But it's still great reading, and in later books he probably deals with it. I'm just grateful that the universe has brought about beings conscious enough to think about and discover the reasons behind all these grand phenomena.

Posted at 2:45 am | link

The Olympics are finally over, in a blaze of color and glory. I will miss the pageantry and the color, not to mention the sports excitement. Sports are one of the few things left in this drab modern life of ours where people can wear bright colors and make a lot of noise without being socially penalized for it. It gives me the opportunity, even if only for a minute or so, to step out of my position of irony, cynicism, regret, ambivalence, and pessimism, and simply celebrate some brilliant athlete's victory. Then it's back to the real world of energy dissipation, dust, laundry, and price tag signs for organic roma tomatoes.

I watched more TV than I have in years. I got a glimpse into the American culture which has passed me by, a multi-racial world of hip-hop and fast food and babes and glitzy cars. Sometimes the ads were more interesting than the sports. They certainly were loud. They will not induce me to get another credit card or to eat at McDonald's, though.

I also say goodbye to the poignant messages about "living your dreams." I know I am being emotionally manipulated, but I feel the emotions anyway. Like the charity solicitations that I mentioned in my last post before this one, the ads and "Olympic moments" are full of innocence and hope masking lifetimes of pain and disappointment. For every Olympian who won a medal of any sort, even for those who were there but didn't win anything, there are hundreds, thousands of people who hoped to be there but whose dreams came up short. What about them? How do you live the dream when you have failed? If you qualify for the Olympics, you are an intense competitor. How do you manage your frustration when your dream fails? The ads only reinforce how fallible and illusory such "dreams" are, and they also show why some of these athletes just keep coming back and back to try again. It is better for me not to draw any parallels or similarities with my own situation, lest I sink into poor taste again.

I now have a word for these cultural bits when innocence and hope cover an underlying reality of grim despair. All I had to do was look into a rather folksy vocabulary subset of ordinary English. These memes of sugar and darkness are bittersweets. For me, the Olympics were full of bittersweets, and I'm sure I'm not the only one to feel that way. Now back to the grey world of dread and irony, and six weeks of Lent to repent for things I have not done.

Posted at 1:50 am | link

Another 85 name and address labels arrived today, all adorned with cute and pathetic cartoons about kids and puppies and spring flowers. They were from a charity for children with cancer. Nothing like spring flowers and puppies to make me think about dying of cancer. The world is full of things like this. There ought to be a word for it: something sweet and innocent which nevertheless is associated with sadness, misery, pain, and slow death. If you are in the right (wrong) mood, even the sound of crickets, birdsong, or surf can make you melancholy. I recently acquired a new sound-effects CD to add to my collection of them. While listening, I imagine that I am on a space voyage far from earth, never to return, and these few minutes of electronically altered natural sounds, along with some photographs, are all that I will ever have left of the natural world of my home planet.

At this point in my physics studies, I cannot stand to look at another sliding block. Nor at another work/energy, potential/kinetic calculation. I've spent far too long on this section and I have to move on. I will be changing to a related and very important subject soon, but will not announce it on this Electron until I have actually done it. Same with upcoming art projects. I am bound by a certain kind of honor not to announce anything for the future which I am not completely certain I can or will do. Thou shalt not boast before thou hast anything to boast about. Perhaps thou shalt not boast at all, as it is most unseemly.

I always find myself circled round by fence after fence of "shalt nots" and "shalts," whether in behavior or artistic choices. Thou shalt not make anything ugly, anything too loud, anything too violent or disturbing. The Client might not like it, or the buyer not buy it, or it simply is in bad taste. Thou shalt not be too aggressive. Thou shalt speak softly. Thou shalt eat vegetables rather than meats or sweets. Thou shalt not speak too much about thyself. Thou shalt not dress in stupid fashions. Thou shalt not be stupid at all. If you are thinking about it, you probably shouldn't do it, unless it involves academic study. Thou shalt not be self-absorbed or self-promoting, but this last bit is ironically recursive, because just the idea of trying not to be self-absorbed is an act of self-absorption. The Eleventh Commandment, right after all those other "shalts" and "shall nots," is: Thou shalt not be boring. And the worst, which I am breaking right now, is, "Thou shalt not whine."

Posted at 2:46 am | link

I've only had a few free minutes between extended work hours and watching the Olympics on TV. After all, I only get to see ski jumping once every four years, right? Does anyone really do that other than Northern European daredevils? It sure looks good, though, especially the brilliant superhero suits the guys wear. Now that Marvel Comics has succumbed to hip-hop and manga, someone else has to look graceful and beautiful in spandex. But what was I saying? The leaping and twirling skaters have grabbed my attention so I haven't done much of what is really important, namely physics.

When I do work on it, I find skiers and ski jumpers in my physics problems. This is pleasantly appropriate. I am not working from Schaum's right now, but from my favorite physics website, The Physics Classroom. The specific problem set I've been working on is at this page which I use both as a paper printout and online. The site uses both diagrams and animations to illustrate the conservation of energy. It is simpler than Schaum's, but the explanations and problems ultimately teach the same thing.

I have just finished going through the problems in the Physics Classroom work/energy section. I will do some of their more difficult equivalents in Schaum's work/energy chapter, and then proceed on to something different. I am also working on page 37 of my graphic novel, which depicts psychomagical special effects, and preparing to start a large commissioned piece which should occupy me through March and April. As the days get longer, with more sunlight, I am less depressed and more willing to do work. Unfortunately, my energy has not been conserved over the winter; it needs to be replenished by an external source.

Posted at 3:15 am | link

Name it and it exists. This has been a cultural belief ever since prehistoric times, and it continues to function, even subliminally, in our own culture. In even the most atheistic, rational, and enlightened scientific mind, to name it is to bring it into being: virtual particles, virtual names, virtual existences. Instantons, superparticles, gravitons, tachyons, neutralinos…. these things exist, for now, only because theorists say they might or should exist. They are not living creatures, they don't have consciousness, they don't answer any questions, but they do have existence, at least until some experiment proves they don't.

The multiple-universe theory currently popular among the more daring theoretical physicists proposes a vast myriad of universes parallel to this one. Each one of them has different original properties and turns out somewhat different, or even radically different from ours. Some collapse almost as soon as they are born. Some are too light, never form stars or galaxies, and drift on in an amorphous cloud until they dissipate. Others form stars that are too massive to survive for long, and they implode, overcome by their own massiveness, into black holes, so that unfortunate universe is a lightless collection of gravitational sinks. And others may be just like ours, except for perhaps one or two details, for instance, that the Baltimore Orioles have a great pitching staff, or that vegetables taste good.

Here in the virtual world of Netland it is almost spring, and the fall of spam e-mail snowflakes has turned to a fall of spam raindrops. The territories on the edge of madness are still populated by the eerie crowd of virtual names, created by spammers with name-generators which search census records and recombine them in a near-infinite set of possibilities. I have received e-mails from Florenza Markmeyer, Ulysses Kaldas, Waldemar Fullager, Maximo McGehee, Heinrike Talmadge, Fanny Kennedy, Phrixus Vivas, Demeter Foote, Briggs Tetreault, Martin Lubikowski, Emmanuel Roper, Adah Cormier, Kaycee Kipnis, Hupprecht Clagon, Maribel McDowell, Milka Mihan, as well as the redoubtable Dagfinn Moroney, the mysterious Yanaton Pawliw, and one of my all-time favorites, Zosimus Brickhouse. What do you mean they don't exist?

They are hungry ghosts, uncounted trillions of them, all hungry for my money, trying with unreal desperation to sell me mortgages, sex aids, penny stocks, and drugs, drugs, and more drugs. In the physical world as well, I receive endless solicitations for my donations, all for worthy causes: animal rescue, impoverished children, sufferers from diseases, women's rights, care for the homeless, schools and colleges I may have attended, or politically correct campaigns. The papers pile up, each one hungry and needy, picking at me with a whole earth's full of un-slakeable want. My entire life savings could be thrown into the neediness of the world with less effect and less splash than just one or two of those virtual raindrops. In the late winter darkness, the hunger of this world's creatures draws me downward like the gravity of that black hole.

I did give a pittance to one or two of these charities, overwhelmed by guilt and by the photographs of neglected kittens and starving children. But that only brought more need to my door, more mailings from more charities, since once a charity has received a donation, they know that I am a "live one" and possibly good for more, so they "share" my address and data with a dozen other ones. I do not feel better for having given anything to them, because for every one I gave anything to, I denied contributions to ten others just as worthy.

And what do they send back to me? In this case, not a kaleidoscopic flow of combinatoric names, but re-iterations of my own name and postal address, printed on decorative stickers to be used as return addresses on envelopes. I have, in the last year or so, received page after page of these stickers, most of them correctly spelled. They are pathetically cheerful, adorned with pictures of colorful flowers, cute puppies and kittens, bright patriotic symbols, tasteful leaves, or kiddie cartoons. Sometimes they are typeset with the first letter of my last name in an Old English script, as if somehow I were a member of a noble family whose ancient and honorable name's initial was etched into the family silver, inscribed on the porcelain table settings, and engrossed above the heraldic arms over the great fireplace.

I counted them. (It was a slow night.) I have, at current count, 943 name and address labels. That's nine hundred and forty-three copies of my name, which, in the virtual world, means nine hundred and forty-three copies of me. I am multiplied by the hundreds, cloned approaching the thousand, all ready to go out in mass mailings for charity. What if each one of them also cloned my give-able money, so that instead of just one grudging contribution, I could give nine hundred and forty-three contributions, flooding the needy world with virtual donations? And then, for each one I sent out, the recipients would then send my name and address to many more, who would then send me back their own requests for aid along with their set of name and address labels for me. The name and address labels would multiply exponentially, until the entire world was filled with nothing but me, me, me, the greatest giver in the world, at least until that universe crashed down under its own weight into a black hole. And even then, the solicitations would not stop, and the ghosts would still multiply, hungrier than ever, as charitable donations swirled out of sight into the endless gravitational maw of the world's need.

Posted at 3:48 am | link

One of my favorite authors is Jorge Luis Borges, whose short stories have inspired me for decades. One of my favorite stories of his is The Zahir, which could be described as an intellectual horror story. It is a tale of obsession, mysticism, and madness, which arises from a banal detail of life. The story is told by a man who is captivated and eventually driven insane by an object called a Zahir. For the definition of this, I quote from the story:

"…the people (in Muslim territories) use it to signify "beings or things which possess the terrible property of being unforgettable, and whose image finally drives one mad.…whoever looked once upon it could thereafter think of nothing else.…"

The Zahir does not have to be something large or important. It can be totally insignificant, until it somehow acquires the Zahir property. There can be only one Zahir in the world at any given time, but it mysteriously embodies itself in one thing after another. In the Borges story, the Zahir is "an ordinary coin worth twenty centavos." The end of the story is quietly terrifying, as the narrator realizes that he will be reduced to a helpless and terminal state of dementia, as his mind is totally taken over by thoughts about the Zahir coin.

I have an unpleasant overabundance of what is called the faculty of "pattern recognition." This faculty is inborn in human beings as an evolutionary advantage; we are told by scientists that our primeval ancestors benefited from being able to make out patterns that signified threat, such as a leopard hidden in the leaves that they could then run away from. Most people exercise their pattern recognition skills in pastimes such as "find-the-word" puzzles, or knitting, or video-games. Scientific and mathematical types probably have a higher level of pattern-seeking mentality, which may lead them to ask questions about features of the universe that other less observant people might not notice. Art also demands a high level of pattern recognition, at least some kinds of art do. For instance, pattern-seeking scientists have attempted to prove that the seemingly chaotic spatter-paintings of Jackson Pollock followed a "fractal" multiplication pattern rather than being just conglomerations of randomly splattered paint. The article is here and you can judge for yourself whether the scientists have decoded the artist. (Some of the links in the article may not work, as it is from 1999.)

I am always trying to see patterns in things. This leads me into social problems as well as that ongoing sin of mine, "sweeping generalizations." What else are those generalizations but pattern recognitions? The trouble is, the patterns may not exist. I may be seeing a relationship between things that occur together but are really uncorrelated. Skeptical scientist types say that this common misperception leads to acceptance of "wrong" beliefs in paranormal powers, astrology, and ultimately any theistic religion, all of which are unacceptable to these warriors of rationalism.

There are things in my life that have some of the properties of a Zahir, though thankfully they are not the all-consuming kind that Borges wrote about. They are little insignificant details of life that simply will not leave my memory. I can still recall a pair of emerald green rain boots on a woman on a rainy street in Williamstown, Massachusetts in the summer of 1972. And there was an infinity sign, or a number 8 (depending on your direction), scratched into a brick in the sidewalk of Oxford Street in Cambridge, Mass. near the Harvard Science Center.

There is a Zahir-like object on a tile in my aunt's bathroom. I knew it in my youth, and it is still there to this day. The tiles in that upstairs bathroom are a pale yellow, speckled with a myriad of tiny black specks which resemble a negative astronomical photograph of a starfield. There are no galaxies there, just tiny black star-dots, seemingly at random. While occupied on the seat in that bathroom, I had ample time to study those tiles. Was every tile the same, or was the sprinkling of specks different for each tile? My visual ability told me that every tile was different. Each tile was, as it were, a separate universe, or at least a different view of one universe. But on one tile, close by the window, I found one particle that was slightly isolated from the rest of them. It had, as it were, a small empty area around it which set it off from the other specks, barely noticeable unless you were looking at it closely from a seated position.

Were there others like it? I studied those tiles day after day, visit after visit, hoping to find another special speck. But this one stood alone. I pointed it out to my cousin, who grew up using that bathroom; I wonder whether he could find it on his next visit home. I certainly could. Let the tiny black spots on the bathroom tiles represent the stars. This one is set apart by an extra millimeter from the others, drawing my attention in with a powerful attraction, even though it may be no bigger than the period you see after this sentence. What might it be? Is it possible that this represents a black hole, a once-blazing star collapsed into itself so that its gravity is so powerful that not even light can escape? Astrophysicists observe that black holes do indeed clear an area around themselves as they vacuum material inwards. The black hole pulls its surroundings into itself, freezes all perceptions on an "event horizon" at its outer limit. Could Borges' Zahir be a form of black hole, in the realm of mind rather than gravity, something that your thoughts orbit round and round before annihilating themselves down its drain? Is there a black hole on a bathroom tile in my aunt's house in Massachusetts? More likely, my overactive pattern recognition has once again betrayed me, leading me to behold a Singularity where other folk would see only a meaningless scatter of specks.

Posted at 4:13 am | link

Just as I was two years ago, I am caught up in the bright pageantry of the Olympics, this time the Winter Olympics. I've written about the Olympics before, since this Electron Weblog is now over two years old. It seems that each Olympics I watch reflects on my different mood for that year. In summer 2004 I was full of hope and purpose, but now in winter 2006 I am chilly and stagnant. I watch the athletes in their triumphs (or failures) with a kind of "achievement lechery," thinking of how much dedication they have, how much support they receive, and how they succeed in just getting to the top competition, yet alone winning in it. And I compare it to my own lack of achievement, staring numbly at the physics page I cannot find the energy to turn, the painting I cannot find the energy to start. What is all this talk about "following your dream?"

Even though I grew up in a land of winter, I never took to winter sports. I tried skating, but I was klutzy, uncomfortable, and unbalanced, and I hated it. I think I put on skis once in my life, with the same results. The only sport I have ever had any skill at was tennis, and I haven't swatted a tennis ball in twenty years. As a kid, I enjoyed sledding, on rare occasions, and that was about the only snow fun I ever had. So when I look at those athletes in their brilliant superhero costumes doing all these daring things, I am in awe of anyone who is brave enough to ski down a mountain or leap and twirl on a skating rink, or slide up and down the curved near-vertical walls of the snowboarding "half-pipe" course. The ski and snowboard aerial acrobatics seem wildly unnatural compared to the more "natural" sports of the Summer Olympics such as running or jumping or swimming. Most anyone who is physically able can run or lift weights or swim at a modest level, but it takes a special kind of person to do ski jumping.

Naturally, I think of physics while I am watching the snowboarders go through their moves. The snowboarder has potential energy while she is at the top of the course. As she descends into the reverse barrel-vault of the course, she gains kinetic energy and speed. She has enough speed to go right up the vertical wall and fly into the air, in a more or less parabolic curve, since the coefficient of friction of the snow on her board is minimal. At the top of her aerial trajectory above the wall, she once again has potential energy but not kinetic; her turns in the air don't affect the total energy. Back down the wall she gains kinetic energy again so her run through the course is a constant see-saw of potential against kinetic energy. But as she moves, she is losing energy, to friction against both snow and air. When she reaches the end of the course, she stops by increasing the friction of the board against the snow. Winter sports are all about friction, or the lack of it on snow and ice. And it's nice to see the young, cheerful American athletes win gold medals in snowboarding physics.

Posted at 2:45 am | link

Sometimes, the Internet can be a wonderful thing. I recently received an e-mail from a Methodist Minister in eastern Pennsylvania, who had somehow come across this Weblog and seen the image of my painting, "The Orange Sail." He wrote to me that he wanted to use this image as an illustration for his sermon this Sunday. He said that my painting evoked the dynamic energy of God's Spirit, seen in the force of the wind that powers a sailboat over the waters. He drew moral and spiritual meaning from the picture, that I had never thought was there! He wanted to use the image in the PowerPoint slide show that accompanied his presentation.

Naturally I said yes, as long as he credited the image to me and included my contact information. I had no idea that ministers were now using PowerPoint, which I associate with business meetings or academic lectures. But this is the modern world and religious folk have to keep up to date, it seems. He said he would also feature the image in the more conventional paper leaflets handed out to the churchgoers.

When I painted "The Orange Sail" last year (from a design I had first made in 1991) all I was thinking of was a pleasant ocean scene which I remember from a beach near Gloucester, Mass. I had not intended any "spiritual" theme at all. It is a pleasant surprise that anyone would find spiritual meaning in it. Every so often I am reminded that my art has viewers, meanings, and consequences that I can in no way foresee. The Internet multiplies the chances of this happening, as does any form of public display. It's something to think about when I am working on art in isolation, not knowing whether anyone will see it or whether it will have any influence on the world.

So, if the few dozen worshippers of a small United Methodist church make it through the wet cold and snow to gather today for their service, they will see an image evoking a calm ocean and the balmy breezes of summer.

Posted at 4:02 am | link

I got up on Sunday at three PM, which is revolting, but I really needed the rest. There was some sunlight, though it was chilly and windy. I set up the panel for picture catalog number 931 (a large commission) and sanded it. Then I added another spray layer of primer coat and let it dry, outside on my terrace. After that I dragged myself out of the house with re-cycling trash in the car, and dumped the re-cyclables into the bins near the shopping center. The winter sun was pale and slanting, in between purple and gold clouds. I visited the supermarket and bought toilet paper and Poland Spring water, purchases which naturally go together. Went into Starbucks and found that my friend the manager is being transferred to another store, where he will continue to invite me to do the art on the "Daily Offerings" panel. I got some espresso beans, as my supply was running out.

Returning to my dwelling, I sprayed a coat of spray gesso on the now-dry board and turned on the computer as twilight fell. Resolved to myself NOT to watch TV or the Superbowl or anything connected with it. Am I a bad American because I don't care about the Superbowl? And why don't I care about Jessica Simpson, Nick Lachey, Brad Pitt, Jennifer Lopez, Jennifer Aniston, the Olsen twins, Lindsey Lohan, Britney Spears, Justin Timberlake, or Angelina Jolie? Their names are all over bright, colorful printed material in the supermarkets and convenience stores. Their lovely hairless bodies are displayed for our viewing. Sometimes I think these may all be the same person, just wearing different clothes. Is this important? Environmental scientist Jesse Ausubel said this bon mot in the January 28-February 3 issue of NEW SCIENTIST magazine when he was peeved over the media's indifference to the "Millennium Ecosystem Assessment:" "…People are like dogs sniffing each other's genitals. Social status and sexuality are what interest us. That's not going to change." Spoken like a scientist.

I painted clear sealant on another wooden plank for a Trader Joe's fruit sign. Finally, the laundry machine was unoccupied and I did two loads of laundry. I don't have a little wifey to do the laundry and keep house for me. She won't type my manuscripts, either. I cranked up the graphics programs and printed out lots of pricetag sheets for Trader Joe's. They pay for the ink cartridges. I did some designing for "tea" pricetags, printed some more, and then the cartridge ran out of ink, at which point rather than install another one, I stopped printing. Out there in Science Land, scientists are really busy doing important scientific work, not these trivial tasks.

I made dinner (no helpful wife to cook, either) which was pasta, into which was thrown some peas, canned tuna fish, and a few cut-up artichoke hearts. That counts as "vegetables," so it was a healthy dinner. Seasoned it with lemon-pepper and grated parmesan cheese, and it wasn't bad. Washed it down with soymilk and Poland Spring water. Cleaned the pots and utensils in the sink (Dear, could you do the dishes? I need to work on my talk for the quantum gravity colloquium…) and went back to the computer, where I found that the Pittsburgh Steelers had beaten the Seattle Seahawks. Who cares about football, it's only one month till spring training.

The laundry is ready, so I have to fold it now. Two more loads remain to be washed. Sorry, my darling subservient helpmeet is not available, because she doesn't exist. I wanted to do art, but I didn't have the time. I wanted to watch one of my "Particle Physics" DVD's, but I didn't have the time, because of the laundry. I am still working on learning the work-energy theorem. This states that the amount of unwashed laundry is complementary to the amount of clean laundry in an entire pile, as long as no new articles of clothing are added to the load. NEW SCIENTIST's current issue has a special feature on robots. I am waiting eagerly for "Rosie," the housekeeping robot predicted in the classic TV show The Jetsons. Alas, the future isn't what it used to be. I need new energy to be added to the system. Espresso beans have now been re-stocked.

Posted at 2:29 am | link

Some of my readers may have wondered why I have not been forthcoming with an entry the last few days. It is because my time has been taken up not only with dental work (which is now done, I hope) but with a lot of art for my day job at Trader Joe's. Our store is doing a lot of sign renovation and I have been kept busy with signs for fruit, vegetables and wine. Signs hang from the ceiling to guide customers to their favorites, and in the last week I've painted, or rather lettered and embellished, plenty of them.

They are done on wood plaques or boards. For some of them, a color base coat is added over a white primer coat. This is done by one of my co-workers, and then I do the writing and decoration. Others are just left plain wood-grain, primed with a sealer coat to keep the paint from being absorbed. The paint is applied not by brush but with opaque acrylic markers, an excellent artist's material which has only appeared in the last decade or so.

Here is an example of one of my produce signs. It's painted on both sides, in acrylic markers on wood. It's about two feet wide, one of a series of four.

And here are two of my wine signs. Spray paint over wood plaque, writing and decoration by acrylic markers, here mostly in metallic colors. Each plaque is about 18 inches wide. These are two of a series of eight, painted on both sides.

Regarding art, I have once again been asked the baffling question why I don't paint more "serious" or "profound" art. I guess vegetables and fruits are not profound, unless they are painted by Cezanne. Honestly, even after all this time, I don't know what counts as "serious" art. The art world is so filled with styles, genres, criticism, and trends that I have no idea where the "serious" stuff is any more. Things that made sense in Cezanne's nineteenth century don't make much sense in our twenty-first. If I'm a "true artist," how do I know what to paint next?

I've done a lot of soul-searching about this. "Do what I like" is not enough of an answer. I like doing a lot of different kinds of art, from architectural studies to geometric abstraction to graphic novels to "traditional" fantasy art. So you know what I concluded? The art I do next is the one I am going to get money for. Sounds totally crass, I suppose, to the "pure" artists who don't care whether their pictures sell. But for me, art is what someone pays for. I suspect a lot of other artists feel that way but may not say it for fear of sounding low or grubby. But if I have a commissioned work with a client waiting to pay me when it's done, that's what I will work on. (Commissioned work, coming this spring…watch this space.) As for the gourmet store: make the sign, drink the wine, but not at the same time.

Posted at 2:43 am | link