Editing 2976: Time Traveler Causes of Death

{{comic
| number    = 2976
| date      = August 23, 2024
| title     = Time Traveler Causes of Death
| image     = time_traveler_causes_of_death_2x.png
| imagesize = 332x677px
| noexpand  = true
| titletext = Many a hungry time traveler has Googled 'trilobites shellfish allergy' only to find their carrier had no coverage in the Ordovician.
}}

==Explanation==
Time travel is a common sci-fi/fantasy plot, in which someone from one era is sent forward or backward in time to another era. Normally, the travel itself goes off without a hitch, with the usual threats to the time traveler being what happens at some point ''after'' they arrive at their destination. More rarely, a time traveler might immediately encounter some hazard because of where their time travel method has deposited them.

This comic takes the latter situation to the extreme, observing different causes of death for potential time travelers through the ages based on the geologic evolution of Earth from its formation over 4 billion years ago to the present; see detailed explanation in the [[#Table of death causes|table]]. The chart shows only the most likely cause for a given period of time, although the title text reveals that there may always be others possible.

The title text suggests that an alternative fate within the "eaten by fish" era is the exact opposite - eating something hazardous. A time traveler, having fortuitously avoided the primary "Starving" fate of the prior era, may try eating a {{w|trilobite}}, a kind of shellfish. They may find that either some existing allergy is triggered by this prehistoric shellfish, or that the creatures of that age spark a new allergic condition that (as a modern human) they were not previously aware they could develop a reaction against. A person with a known allergy might check for the possible presence of a problematic ingredient in a potential snack by referencing online resources - a facility that is not available here, with the smartphone stuck in the past, long before any network is available to connect to (notwithstanding that Google Search has not existed historically for more than three decades<!-- specifically 1996+, by one measure, but futureproofing the explanation a little-->). Alternatively, suspecting the food they've eaten has not agreed with them, they could find they are denied easy access to the best online information on how to properly treat their symptoms.

===Table of death causes===
{| class=wikitable
! scope="col" | Cause of death
! Scope=“col” | Time frame
! scope="col" | Explanation
|-
| Lava || Earth Forms || During the formation of the Earth, the surface was a hellish landscape of lava.{{fact}} 
|-
| Asphyxiation || 4 billion years ago || Before {{w|cyanobacteria}} started photosynthesizing and producing oxygen, the atmosphere of the Earth was mainly composed of hydrogen sulfide, methane and carbon dioxide, without the significant amount of oxygen that humans need to breathe.
|-
| Meteors || 3.9 billion years ago || During the hypothesized {{w|Late Heavy Bombardment}}, the Earth's surface was subjected to a large number of asteroid and comet impacts, destroying much of Earth's early crust. According to the table, the heavy bombardment was so severe that this was the most likely cause of death during a period when there was still no oxygen. Even when these meteors came at an alarming rate, however, the chance of being hit by one of these before asphyxiation due to an atmosphere without any oxygen seems remote. Of course, if the time machine had some oxygen along with it and the reason people died from lack of oxygen was that they stayed there for a long time, the chance of death-by-meteor would increase.
|-
| Asphyxiation || 3 billion years ago || See above. 
|-
| Slightly slower asphyxiation || 2 billion years ago|| Cyanobacteria had started photosynthesizing, leading to the {{w|Great Oxygenation Event|Oxygen Catastrophe}}, but oxygen levels still weren’t high enough to support human life. 
|-
| Freezing || Less than 1 billion years ago || During the {{w|Cryogenian|Cryogenian Ice Age}}, the Earth’s temperature fell to -12°C, much too cold to support human life if not properly prepared.
|-
| Starving || 600 to 485 million years ago || During this time, the temperature was mild and comfortable; however, the only life during this time was single-cell organisms and – especially later – tiny multicellular organisms, which are very difficult to gather and may not be sufficiently healthy and nutritious. (Imagine surviving only on bacteria today.)
|-
| Eaten by fish || 485 to 250 million years ago || During the {{w|Great Ordovician Biodiversification Event}} and subsequent times, fish {{w|Evolution of fish|evolved jaws}} and some species grew quite large.
|-
| Trampled || 252 to 66 million years ago || The {{w|Mesozoic Era}} is often called the “Age of Dinosaurs." The majority of these dinosaurs were herbivorous and many were quite large, so being eaten would be less likely than being trampled on.
Note that this is an almost exact inversion of what happens in the classic story ''{{w|A Sound of Thunder}}'', in which the traveler survives personally unscathed but tramples an 'age of dinosaur' creature (to unfortunate effect).
|-
| Eaten by mammals || 66 million years ago to sometime before now || The {{w|Cenozoic Era}}, which began 66 million years ago, is often referred to as the "Age of Mammals". Though some eras have more likely causes of death (such as wars, but that would basically be during the "Now" period in the table), overall being eaten by large mammals is probably the biggest risk.
|-
| Time machine door gets stuck || Roughly present day || As the timeline approaches the present day, the conditions on Earth become more than suitable enough for a human time traveler to survive extended periods of time &mdash; as evidenced by the fact hominids and early humans begin to emerge. As such there's nothing else more likely to kill them than getting stuck in the time machine and dying of thirst or starvation (or, if the time machine is air-tight, asphyxiating). This assumes the time machine is also a {{w|Faraday Cage}} (that can block the signal of an emergency call) or the traveler doesn't take their phone with them, although the title text indicates they will. Or that the "Now" period extends back before cell phones and compatible cellular networks, maybe covering the entire period of human civilization. It could also be that time travel is deadly if the machine door does not close all the way -- or that time travel to the past (for a distance longer than one human lifetime) is deadly from a present-day point of view, if the time machine door gets stuck *with the time traveler outside the machine*! But mostly it is a punchline comparing severely dangerous situations to severely harmless ones.
|-
|}

==Transcript==
:[A chart with a time line going from top to bottom is shown. Starting when the Earth forms and ending at present day. The chart is a rectangle divided into 11 segments. Each segment has a label written inside it, except the bottom which is too thin, thus the label is to the right of the chart with an arrow pointing to the segment. The left side of the chart is a timeline with ticks and labels for the time period. At the top an arrow points to the top left corner of the chart with a label indicating the starting time. And then there are 5 ticks, the first four equidistant and then only half the distance for the last tick. A final label is at the bottom of the chart. Above the chart there is a heading:]
:Top causes of death for time travelers by geologic era:

:[Text in the table from the top, with the time to the left differentiated from the labels which are indented:]
:Earth forms
::Lava
::Asphyxiation
:4 billion years ago
::Meteors
::Asphyxiation
:3 billion years ago
:2 billion years ago
::Slightly slower asphyxiation
:1 billion years ago
::Freezing
::Starving
:500 million years ago
::Eaten by fish
::Trampled
::Eaten by mammals
:Now
::Time machine door gets stuck

== Trivia ==

Modern adults can actually have great difficulty surviving without modern conveniences, and may die of freezing if released into an earlier era than they are familiar with. Children of certain ages may thrive well, neither freezing or being eaten by mammals, after a period of adaptation.

{{comic discussion}}

[[Category:Timelines]]
[[Category:Time travel]]
[[Category:Geology]]
[[Category:Animals]]