The ZIP drug blocks communication between these complementary neurons. The problem of using ZIP-like drugs is the targeting of individual memories. In humans, no biomarkers separate out good from bad memories.
Where short-term memory ends and long-term memory begins is difficult to quantify. Do you remember this book's introduction? I'm thinking that I shouldn't bet on it. I am sure you know what you had for breakfast, if you ate one. Unless you have the same thing every morning, you probably won't remember this morning's breakfast a year from now. If the introduction had an emotional impact, though, then it went into your long-term memory. Something that affects you emotionally, either pleasantly or not, releases norepinephrine, a promoter of a protein cocktail in the amygdala (the processing center for your emotions and the fight/flight/freeze response to a threat). If a drug that lowers the production of norepinephrine could be applied shortly after a traumatic event, it might prevent the formation of a long-term memory about the trauma. Medics on a battlefield could use the drugs with soldiers to cut down on instances of PTSD.
HOLOGRAPHIC REALITY
Is being called two-dimensional an insult? It shouldn't be, because what we perceive as our three-dimensional universe might be nothing more than two-dimensional source code projected across a horizon. Some speculation proposes that we might all be holograms, scattered light that is reconstructed into a 3-D representation of the original 2-D version. This theory is called the holographic principle.
The holographic universe was first proposed by Gerard ‘t Hooft of the University of Utrecht in the Netherlands.10 If it is true, are you real? Or rather, the type of real you think you are? The principle suggests that you are actually a 3-D representation of a flat 2-D version of yourself that is hanging out at the boundary of the universe (wherever that is).
If we really are all holograms, a lot of cosmological questions would be answered, including how to connect relativity with quantum mechanics. The principle suggests that gravity can be described in a theory in one less dimension that has no gravity. A 2-D universe without gravity is able to project the effects of gravity (and even black holes) in a 3-D universe.
Isn't this a bit like the stereoscopic vision we talked about, where we perceive 3-D from 2-D images?
LET'S GET DEEP INTO SOME SCIENCE FICTION
I have described a hologram as reconstructed light, but I left out an important bit of information: the light can be reconstructed at some future time long after the original source is gone. The holographic principle provides science fiction creators with another solid idea that can be useful: time travel.
Star Trek: The Next Generation came close to this idea, only instead of holograms, they used teleporter technology. In the episode “Relics,” Captain Montgomery Scott (famously known as Commander Scotty, the chief engineer for Kirk's Enterprise in the original Star Trek series) is reconstructed in the twenty-fourth century after having his pattern stored for seventy-five years in a teleporter buffer.11
Another science fiction idea is to completely give in to the holographic principle and accept that earthlings reside in a holographic universe. Then perhaps a select few heroes and villains become self-aware enough to modify the coding of their 2-D templates. What would happen? Would they be godlike in their abilities? Or, perhaps by simply shifting the position of a hologram, a starship would have the appearance of flying faster than light. All of these wild ideas are consistent with the holographic principle.
The next time you read in DC Comics about all the reality-warping power of Mr. Mxyzptlk (from the fifth dimension), just know that he might get these powers by manipulating a 2-D projection of the earth from a higher dimension. He does love a good practical joke at the expense of poor old Superman.
HOLOGRAPHIC THEORY AND BLACK HOLES
The holographic principle also suggests that the event horizon of a black hole is a recorder and a projector. It records all the information of what has fallen into it. According to this model, nothing ever really falls into a black hole. Rather, objects that enter become spread out around the event horizon. The interior of the black hole is nothing more than an illusion and therefore inaccessible to anyone on the outside. As the black hole evaporates, all the stored information is encoded in the radiation. Therefore this principle offers up a theoretical solution to the black hole information paradox (a contradiction between general relativity and quantum mechanics) described in bonus 2 of chapter 7.
PARTING COMMENTS
Reality is frequently inaccurate.
—Douglas Adams, The Restaurant at the End of the Universe
Your view of the world (your reality) can be computer augmented with real-time information. If you are less interested in the reality you are stuck with, change it. Technologies to create user-generated realities exist for leisure or therapy. Keep in mind it might be that messing with reality is a slippery slope. Hello, The Matrix. The same is true for adding false memories or erasing true ones.
Now that you know about the holographic principle, I want to leave you with something to consider. If Star Trek: The Next Generation had been written to exist in a holographic universe, it would have been turtles all the way down (meaning infinite regression) because on the holodeck, you'd be creating holograms within holograms.
The End Is Nigh.
—Walter Kovacs, aka Rorschach, from Alan Moore's Watchmen (1986)
This isn't the happiest of chapters. Fittingly placed at the end of this book, the chapter is all about endings. As long as time has a direction, then atoms, humans, the earth, the sun, the Milky Way, and the universe will all at some point…just end. Everything has an expiration date. This final chapter explains the how and why of some of the grand finales.
SPEAKING OF ENDINGS (AN AUTHOR'S CONFESSION)
I remember one time when I was standing by the side of the road holding up a sign that read, The end is near! Turn around and save yourself! This rude driver shot me the finger as he passed, yelling that I was an apocalyptic a-hole.
To be honest, it sort of hurt my feelings. Anyway, next I heard tires screeching and a loud splash. Then it hit me. My sign should probably have said, Bridge out. Oh well, live and learn, or die.
Okay, back to the science.
THE END OF THE INDIVIDUAL
All life, all the way down to cells, has a metabolism, and all metabolisms wear down. Chapter 9 covered fraying telomeres and the Hayflick limit along with other aging indicators. So, evidence of you getting older does exist. For some people, looking into a mirror just isn't enough. Chapter 9 also gave some scientific hope for biological immortality, and then chapter 10 hinted at downloading your mind into a computer.
It isn't just us carbon-based organics who wear out. Whether they are our friends or overlords, machines need to be considered in this ending game. If it has moveable parts, it ages over time and ages more quickly with use (wear and tear).
If you think we can all go on forever as posthumans who share our virtual living space with AIs, then you need to know one key fact: the party could go on for quite a while, just not forever. Thanks a lot, entropy! I will tell you all about the “e” word soon. For now, just know that both metabolic and mechanical systems need fuel. Someday the universe will be unable to provide it.
As you continue along the path of this chapter, you will discover that all the trails toward immortality fade away. The word immortality should include “really, really long but temporary” in its definition.
THE END OF THE HUMAN SPECIES
Something to ponder: our species might be the first to notice an upcoming extinction event ahead of time.
Unlike the end of an individual, the end of humanity is very speculative. Many different statistical models predict the number of years we might have left. Some include extinction-level events like asteroid strikes, a nuclear war, and overpopulation, all of which chum up the science fiction waters.
Others are based on the average number of years a hominid species has survived in the past. In a spe
ech given at Oxford University's debating society, Stephen Hawking stated his belief that, unless we get off the earth, our species has about one thousand years before extinction.1
This is more optimistic than the fifty-fifty chance of surviving until the end of this century astronomer Martin Rees proposed in his gloomy book Our Final Hour: A Scientist's Warning—How Terror, Error, and Environmental Disaster Threaten Humankind's Future in This Century—On Earth and Beyond.2 His probability calculation is based on the danger of us not truly understanding how destructive our technology really is. I wonder if he reads a lot of science fiction.
I'm not going to give you any odds based on my beliefs. Instead I'll present some facts and you can draw your own conclusions. Let's begin with a few of the local endings from our past. Today it is estimated that 99.9 percent of all species that have ever existed are gone.3 The culprits behind the extinctions are volcanic eruptions, asteroid impacts, and temperature change. These are natural causes. The human-made ones were discussed in chapter 11.
The greatest “hits” of Earth extinctions:
Ordovician-Silurian 440 million years ago (MYA), 60 percent to 70 percent of all species went extinct. The probable cause was a combination of falling sea levels and glaciation.4
Late Devonian 360 MYA, 70 percent of all species went extinct. The probable cause was global cooling and depleted oxygen in the oceans.
Permian-Triassic (also known as the Great Dying) 250 MYA, 96 percent of all marine species and 70 percent of land species were extinct. The cause might have been the acidification of oceans from dissolved carbon dioxide thanks to volcanic eruptions. So much for the bulk of the species coming out during the Cambrian explosion. (See chapter 8 for what exploded.)
Triassic-Jurassic 200 MYA, 70 percent to 75 percent of all species became extinct. The probable cause was the sudden release of carbon dioxide from volcanic activity.
Cretaceous-Paleogene (also known as the K-T extinction) 65 MYA, 75 percent of all species became extinct. Bye-bye, dinosaurs. The possible cause could have been an asteroid impact, or volcanism, or a combination of the two.
The Holocene extinction (nicknamed the “sixth extinction” and also referred to as the Anthropocene extinction): this is happening now. Until the industrial revolution came along, two vertebrate species out of ten thousand went extinct every one hundred years. According to that number, nine species should have disappeared in the past century. Instead, 477 disappeared.5 If the increase in greenhouse gas continues at its current rate, one in six species will face extinction by 2099.
ROID RAGE (DESTRUCTION BY ASTEROID)
Fig. 21.1. Illustration of an asteroid hurtling toward Earth. (iStock Photo/RomoloTavani.)
Big rocky chunks are inconsiderate enough to crash down on Earth about every 500,000 years. This includes asteroids and their speedy comet cousins. The goodish news is that these rude drop-ins haven't all been extinction-level events. The badish news is that, according to the geological record, an asteroid extinction event has occurred every twenty-six million years.6
Scientists are seeking an explanation for this pattern. Here are some of their ideas for why the earth gets stoned, none of which are related to peer pressure. They are all speculative and extraterrestrial.
Planet X A Neptune-sized planet might be orbiting the sun every fifteen thousand years and periodically causing comet disturbances. Although not directly observed (if only it were that easy), its theorized existence is inferred from the gravitational tugs on stellar things we can see, most of which are things we don't want tugged. Hence our interest.
Astronomers estimate that Planet X has ten times the mass of the earth, so if we knew where to look, we'd probably be able to see it with a powerful telescope. For now, we can only theorize its orbit.7
Companion star to the sun A hypothetical star named Nemesis is postulated to be hanging out past the Oort cloud and circling our sun in a wide, elliptical orbit.8 With a name like Nemesis, how could it not be evil? As it periodically approaches, it disrupts billions of comets in the Oort cloud with its gravity and shooting them at the earth.
By the way, Nemesis's nickname is Death Star. The math for its orbit might work out, but there is no evidence for its existence. Remember, math can drive science, but it is not science itself.
If Nemesis does exist then it is probably a brown dwarf, a small star with insufficient mass to maintain the nuclear fusion of hydrogen. This means it will be small and dim and therefore hard to detect directly.
Oscillations through the galactic plane Instead of (or in addition to) another sun or planet perturbing the comets, it might be that our own sun's wavy journey through the Milky Way causes all or some of the problems. The sun moves up and down as it circles the center of the Milky Way. Its route is not much different than that of a wooden horse bopping up and down on a carousel.
This oscillation exposes our solar system to gravity differentials (changes in gravity) that affect material in the Oort cloud. The movement also changes how much cosmic radiation we are exposed to. For example, the sun passes through the north side (upper region) of the Milky Way about every sixty-two million years.9 Because it is exposed to an excess of cosmic rays during this time, our environment is impacted with weather changes.
For the record, there is no “up” or “north” in space.
Fig. 21.2. Illustration of the merry-go-round Milky Way.
Dark matter This is not about asteroids, but it does provide a possible explanation for the natural pattern of extinctions. As the sun bobs through the galaxy on its carousel, it might pass through clumps of dark matter, an acquaintance of yours from the third interlude. These particles will fly through the center of the earth and possibly affect the core's temperature. The results would be volcanic eruptions (hello, Krakatoa) and rising seas. This is the most speculative of the causes for mass extinction because, other than gravity, scientists aren't sure what dark matter interacts with.
IS ANYONE WATCHING OUT FOR THESE ROCKS AND ICE BALLS?
To detect these wandering asteroids and comets, astronomers rely on both ground-based and space-based telescopes. The Jet Propulsion Laboratory at the California Institute of Technology has recorded about fifteen thousand near-Earth objects (NEOs).10
Not all asteroids are created equal. The dinosaur killer of the Cretaceous-Paleogene extinction, which left its footprint in what is now modern-day Mexico, was about ten kilometers wide (6.2 miles).11 Ninety-five percent of asteroids this size or larger have been identified, and their orbits are tracked by NASA. Ninety percent of medium-sized asteroids, ranging from one to ten kilometers (0.62 to 6.2 miles) wide, are under similar surveillance.
The small ones, less than one kilometer wide, are largely unknown. They can drop down faster than a bullet. Most of them will explode in orbit due to the kinetic energy involved with hitting the atmosphere. Those that survive are most likely to land in oceans. If they were to hit land, cities could be damaged, but they do not pose extinction-level threats.
A twenty-meter meteor, labeled 2012 DA14, exploded twelve miles above Chelyabinsk Oblast in Russia in 2013.12 The explosion was about thirty times greater than the atomic bomb dropped on Hiroshima. The shock wave spread out and damaged thousands of buildings, but fortunately no deaths were reported.
IF THE BIGGER NEOS TARGET EARTH, CAN THEY BE STOPPED?
Detection is only half of our defense system. The other is deflection. To stop an asteroid, you need to nudge it a bit and alter its path. Early detection is therefore crucial. The farther away the uninvited guest is, the less of a nudge is necessary to change its trajectory. If it is far enough out from Earth, our space engineers might only need to change its velocity by a couple of millimeters per second.
How could they do it? The boring answer is that they hit it with a projectile. A more elegant solution is to use a gravity tractor. This is when you send an object (artificial or otherwise) to a position near the asteroid and allow the nearly infinitesimal gravitational attractio
n between them to nudge the asteroid slightly.
An offending comet might be treated a little differently, and in a way that is a little showier: launch a rocket and detonate a nuclear bomb close to the ice ball. If the math is calculated correctly, enough of the surface will boil away to change the comet's trajectory so that it bypasses Earth. If this happened in science fiction, the engineer would be sweating out the complicated calculations. Keep in mind that comets travel twice as fast as asteroids, and your team has only one rocket.
No matter your choice of deflection, it will clearly have more chance of being effective than the non-science method used for the 1998 film Armageddon. That idea was so zany it isn't worth addressing in a book interested in science. I will, however, comment on the crazy way the heroes get to the asteroid, which involves a slingshot maneuver of a 1990s’ NASA space shuttle around the moon and then landing it on the offending rock.
I'm not certain how they failed to notice an asteroid the size of Texas until it was only eighteen days away.
As fate (coincidence, or possibly film studio competition) would have it, the movie Deep Impact came out the same year. This one is about a comet hurtling toward Earth, and the plot attempted to include actual science. And it didn't do a bad job. Not perfect, but not bad. Keep in mind that an Orion-class ship is a nuclear rocket (see chapter 17 for details), not one that uses a chemical engine as is mentioned in the movie.
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