INTERSTELLAR TRAVELINTERSTELLAR TRAVEL

Name:Amit samrat mauryaName:Amit samrat mauryaBranch: ECE 3Branch: ECE 3 rdrd year year

Motivation: Fermi’s ParadoxMotivation: Fermi’s Paradox

If the chances of developing a If the chances of developing a technological civilization are 1 in a technological civilization are 1 in a million:million: 100,000100,000 civilizationscivilizations in the galaxyin the galaxy This is an application of the This is an application of the Drake Drake

EquationEquation, but , but ignoringignoring the the Lifetime Lifetime of civilizationsof civilizations

If these are spread over the lifetime of the If these are spread over the lifetime of the Galaxy, the time between civilizations is about Galaxy, the time between civilizations is about 50,000 years50,000 years

Fermi’s ParadoxFermi’s ParadoxWith such a long time, a civilization might With such a long time, a civilization might

be able to colonize the Galaxy or at least be able to colonize the Galaxy or at least make its presence knownmake its presence known

They could at least send self-replicating They could at least send self-replicating machinesmachines

Solutions to Fermi’s ParadoxSolutions to Fermi’s Paradox

There are three solutions to Fermi’s There are three solutions to Fermi’s Paradox:Paradox:

1.1. We are aloneWe are alone2.2. A galactic civilization exists, but it remains A galactic civilization exists, but it remains

hidden from ushidden from us3.3. Other civilizations exist, but none have Other civilizations exist, but none have

colonized the galaxy. Why?colonized the galaxy. Why?1.1. No interest in doing soNo interest in doing so2.2. Self-annihilationSelf-annihilation3.3. Technological difficultiesTechnological difficulties

IntroductionIntroduction In order to travel to In order to travel to

the stars, colonize the stars, colonize other worlds, and other worlds, and establish an establish an Everlasting Galactic Everlasting Galactic Empire, we will need Empire, we will need interstellar travelinterstellar travel

Rocket ScienceRocket Science

Current rockets use Current rockets use chemicalchemical fuels fuels

These can be solids, These can be solids, liquids, or gasesliquids, or gases

Efficiency of a rocket Efficiency of a rocket measured with the measured with the mass ratiomass ratio = = Mass with fuel / Mass Mass with fuel / Mass

without fuelwithout fuel

Rocket ScienceRocket Science To escape the gravity To escape the gravity

of the Earth need a of the Earth need a mass ratio of ~39mass ratio of ~39

Single stage rockets Single stage rockets have mass ratios of have mass ratios of ~15 or less~15 or less

This is not enough, so This is not enough, so we can’t leave the we can’t leave the EarthEarth

Or can we?Or can we?

Multistage RocketsMultistage Rockets

Distances to StarsDistances to Stars

The nearest star system (Alpha Centauri) The nearest star system (Alpha Centauri) is 4 light-years away (40 trillion km)is 4 light-years away (40 trillion km)

At 60mph, this would take… 44 million At 60mph, this would take… 44 million yearsyears

At 17,000mph, this would take just 160,000 At 17,000mph, this would take just 160,000 yearsyears

At this speed, it would take a At this speed, it would take a billion years to reach the center billion years to reach the center of our Galaxyof our Galaxy

What can we do?What can we do?

We need to go faster!We need to go faster! It’s all a mater of getting higher efficiency It’s all a mater of getting higher efficiency

from our fuelfrom our fuel

I can make 0.5 past light speed!

Nuclear RocketsNuclear Rockets

Use fission to heat Use fission to heat hydrogen gas, which hydrogen gas, which provides the thrustprovides the thrust

Fuse small pellets of Fuse small pellets of hydrogen, the energy hydrogen, the energy released moves it released moves it forwardforward

Set off a nuclear Set off a nuclear bomb behind youbomb behind you

Ion DrivesIon Drives

Shoot out ions from light-weight gasesShoot out ions from light-weight gases Little thrust, but can work for longer times and Little thrust, but can work for longer times and

therefore get large velocitiestherefore get large velocities

Solar SailsSolar Sails

Use the pressure Use the pressure from photons of light from photons of light to push the craft to push the craft forward- like wind on forward- like wind on a sail.a sail.

Can also use lasersCan also use lasers

Antimatter is like regular matter but with Antimatter is like regular matter but with opposite chargeopposite charge

When antimatter and matter meet, they When antimatter and matter meet, they completely annihilate each other producing completely annihilate each other producing energyenergy

Antimatter EnginesAntimatter Engines

Like the solar sail, an Like the solar sail, an interstellar ramjet interstellar ramjet carries no fuelcarries no fuel

Take hydrogen from Take hydrogen from space and fuse itspace and fuse it

RamjetsRamjets

To Infinity, and Beyond!To Infinity, and Beyond!

These new These new technologies allow technologies allow light-weight space light-weight space craft to reach very craft to reach very high speeds with very high speeds with very little fuel.little fuel.

In order to go faster In order to go faster we just need to run we just need to run the engine for a the engine for a longer timelonger time

But then this guy came along…But then this guy came along…

Image credit: Kevin Hainline

A Maximum SpeedA Maximum Speed

The speed of light in a The speed of light in a vacuum is always a vacuum is always a constantconstant with respect to with respect to anyany observer. observer.

This speed, c, isThis speed, c, is 300,000 km/s300,000 km/s 186,000 miles/s186,000 miles/s 1.8 terra furlongs/fortnight1.8 terra furlongs/fortnight

Nothing can travel faster Nothing can travel faster than lightthan light

Special RelativitySpecial Relativity

All motion is relativeAll motion is relativeMany weird effects will happen when Many weird effects will happen when

special relativity is applied, but I’ll only special relativity is applied, but I’ll only mention a few:mention a few:Moving clocks run slower as seen by a Moving clocks run slower as seen by a

stationary observer stationary observer time dilationtime dilationDistances are contracted along the direction Distances are contracted along the direction

of motion of a moving object of motion of a moving object length length contractioncontraction

Special RelativitySpecial Relativity

At 99.99% of c, to go to Vega (25 At 99.99% of c, to go to Vega (25 light-years away) and back:light-years away) and back: Space ship frame: 8 monthsSpace ship frame: 8 months Earth (stationary) frame: 50 yearsEarth (stationary) frame: 50 years

But light takes 50 years to travel But light takes 50 years to travel 50 light-years, yet you do this in 8 50 light-years, yet you do this in 8 months:months: Length contraction: you travel 0.4 Length contraction: you travel 0.4

light-year rather than 25 light-yearlight-year rather than 25 light-year

General Relativity to the Rescue?General Relativity to the Rescue?

WormholesWormholes

A highly curved A highly curved region of space could region of space could intersect another intersect another region of space and region of space and form a hole between form a hole between themthem

These wormholes are These wormholes are unstable and collapseunstable and collapse if anything goes if anything goes through themthrough them

The Alternative: Interstellar ArksThe Alternative: Interstellar Arks

Use conventional technology, but be prepared Use conventional technology, but be prepared to wait a very long timeto wait a very long time

The original travelers will die and new ones will The original travelers will die and new ones will be born before reaching the destinationbe born before reaching the destination

Or you could place Or you could place everyone in suspended everyone in suspended animation for thousands animation for thousands of yearsof years

QuestionsQuestions

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